This PDF file contains the front matter associated with SPIE Proceedings Volume 7847, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

We report on the molecular beam epitaxial growth and characterization of In(Ga)N nanowires on Si(111) substrates. We also describe the growth and optical properties of InGaN/GaN dot-in-a-wire heterostructures on Si(111) substrates with emission in the green, yellow, and red wavelength range. The design, fabrication, and characterization of In(Ga)N nanowire solar cells and LEDs are discussed. InN p-i-n axial nanowire homojunction solar cells exhibit a promising short-circuit current density of ~ 14.4 mA/cm² and an energy conversion efficiency of ~ 0.68% under 1-sun, AM1.5G illumination. Strong green, yellow, and amber emission has also been achieved from InGaN/GaN dot-in-a-wire LEDs at room temperature.

Solvent-free, photo-curable, transparent, colorless and haze-free liquid optical polymer materials are primary choices for lenses in wafer level optics. Advanced lens materials are being explored for quality optical, thermal and mechanical properties. Such materials are desired to pass thermal reliability tests, survive stack-reflow processes, have low coefficient of thermal expansion, have high refractive index and extreme dispersion, possess low stress and shrinkage and etc. Novel nanocomposite materials based on 1) finely constructed core-shell nanoparticles with photopolymerizable surfactant crosslink function groups and 2) compatible polymer matrices are promising candidates for imaging and sensing systems with breakthrough performance.

Photoluminescence (PL) and absorption measurements have been made on CdSe_1-xS_x nanoparticles with x=0.69 to x=1 using a process that should lead a graded sulfur fraction where the sulfur fraction is lowest in the core. There is a systematic increase in the 1S_3/2→1S_e transition energy and the 1S_e→1S_3/2 PL emission energy that can be attributed to an increasing sulfur concentration. The quantum yield is ~30% for 0.69≤x≤0.83. It decreases to 0.7% for higher values as x approaches 1. The higher quantum yields for x≤0.83 may be due to the graded sulfur concentration that leads to a thermal barrier that reduces non-radiative recombination at the surface. Temperature dependent PL measurements on a x=0.83 sample are consistent with two PL lifetimes where the longer one (~30 ns) is nearly temperature independent and could arise from a fraction of the nanoparticles having a lower concentration of non-radiative recombination sites. The shorter component can be accounted for by thermal activation to surface non-radiative recombination sites with an activation energy of 9.6 meV.

Photodiode (PD) is a key component in optical transmission and optical measurement systems. In this paper, we present the design and fabrication of traveling-wave edge-coupled Unitraveling Carrier (UTC) PD. The fabricated UTC PD with 40μm×5μm waveguide shows 3dB bandwidth 13GHZ and 32GHz under 0 biases and -1V respectively. In parallel, PIN PD was also fabricated for comparison and only shows 4GHz and 18GHz under same bias conditions. This indicates the UTC PD is superior to the PIN PD for higher speed operation, especially in application of system without power supply.

Nitrogen status is an important factor for evaluating the growth of rice or the amount of nitrogen fertilizers needed per rice field. It can be done easily and cheaply by using a leaf color chart. However, the accuracy of the resulting color level depends on the ability of the farmer to compare the leaf color with the reference chart as well as on the direction of Sun light. With this issue in mind, this paper proposes a low-cost light-emitting-diode (LED) based leaf color meter that can be used to estimate the nitrogen level needed in the rice field. In particular, we show how we integrate an off-the-shelf green 562-nm wavelength LED, a silicon photodiode, an 8-bit microcontroller, and a 6×1 LED panel in a compact packaging style for the implementation of this needed leaf color analyzer. The total cost is only USD39. Field test results confirm that key leaf color levels of 2, 3, and 4 can be identified. Other key features are ease of use and upgradability for different color levels.

In order to study the performance of MRPC, which will be used for the upgrade of the Endcap TOF in BES III, a T0 system is composed of high speed response PMTs H6533 coupling with BC420 plastic scintillators. Because the T0 system should offer a toughly strict timing start, the high precision electronics based on VME system were used to test the SPS (single-photoelectron spectrum) of H6533 PMT. A suitable operation voltage for optimal performance is confirmed by researching the dependence relationship between the PMT gain and energy resolution of SPS (single-photoelectron spectrum). At the end, the timing resolution of this type of T0 system was 41.6 ps in the cosmic ray test and 39.1 ps in the proto beam test.

Investigating the effects of solvents on the performance of poly(3-hexylthiophene-2,5-diy1) (P3HT):C61-butyric acid methyl ester (PCBM) bulk heterojunction solar cells, we found the short current density (Jsc), fill factor(FF),and power conversion efficiency (η) of a cell with a photo-active layer made using materials dissolved in a higher boiling point solvent to be higher than those of a cell made using the same materials dissolved in a low boiling point solvent. Evaluating the surface morphology, charge mobility, and current-voltage curve of cells made using different solvents, we concluded that the polymer films using a higher boiling point solvent had longtime to self-organize, got a higher degree of crystalline, led to lower device series resistance, thereby increased the short current density (Jsc), fill factor(FF),and power conversion efficiency (η) of the photovoltaic devices.

Image restoration for constructing high-spatial-resolution images in an imaging system which realizes indirectly far-filed imaging by integrating the microlenses array with LCD is reported. We have investigated the indirectly far-field imaging condition where adjacent sampling points contribute the detected signal. Experimental setup with microlens of 500 μm diameter and 8 mm focal length is built to prove this condition by studying performance of image restoration using modified point spread function (PSF). Since any one iterative method is not optimal for all image deblurring problems, some deblurring algorithms including direct deconvolution and iterative deconvolution are applied to our imaging system and we compared the effectiveness of these iterative procedures to choose right one for our use.

Towards the development of high efficient GaN-based Vertical Cavity devices, the fabrication of cracks-free high reflective semiconductor mirrors is still an issue. For near-UV operating devices, one of the best solution is the use of AlGaN/GaN materials family. With a relatively high Al molar fraction in AlGaN, a large enough index contrast can be achieved to fabricate high reflectivity mirrors. However, the lattice mismatch between AlGaN and GaN increases with the Al molar fraction and induces a lot of cracks in the structure which affect its optical and electrical properties. Moreover, for a regrowth of an active layer on the top of the mirror, it is necessary to suppress crack generations to achieve a smooth surface. In this work, asymmetrical designs were investigated for the modeling of fully-strained AlGaN/GaN distributed Bragg Reflectors with crack-free surfaces. First, the critical thickness of MOVPE-grown AlGaN on GaN-on-sapphire templates was experimentally determined and modeled. Then, several AlGaN/GaN mirrors with various Al molar fractions and asymmetry factors were simulated demonstrating that non relaxed DBRs could be obtained with adequate parameters. Finally, it has also been shown that there is a best suited Al molar fraction in AlGaN for each DBR centering wavelength.

Light beam propagation at a prism-magnetic fluid film interface is experimentally studied. The magnetic fluid is made through dispersion of synthesized cigar-shaped sub-micron particles of Fe₂O₃ in an oil solution. This was injected into a glass cell with an active area of 10mm² and a depth ranging from 10 microns to 30 microns whose base is a glass microscope slide and on the top it was covered with a glass prism. The set up was developed by one of the authors to measure light switching at a prism-liquid crystal interface in a previous publication.¹ Polarized Light (TE or TM) from a He-Ne laser impinges at the prism-magnetic film interface. The external reflected light is detected by a photodiode connected to a data acquisition system. Since the properties of the magnetic fluid can be modulated by external magnetic fields, we investigated the effects of the magnetic field on the refractive index of the magnetic fluid. For our magnetic fluid, the reflection of light has been investigated as a function of particles concentration and thickness of the films with a wavelength of 633nm and both TE and TM polarization, and applied magnetic fields up to 25 Oe. It was found that the intensity of reflected light increases with increasing magnetic field up to 4 times the initial value, and saturates at 20 Oe for TE light, while decreases with increasing magnetic field up to 4 times less for TM light with the same saturation value. Moreover, under a given magnetic field, the output light increases with the increasing film thickness in TE polarization, and decreases with the increasing film thickness in TM case. The refractive index of the magnetic fluid depends on the concentration of the dilute oil-based magnetic fluid under zero field. These behaviors are explained in terms of the organization of the submicron particles when the magnetic field is applied.² The cigar-shaped sub-micron particles are oriented along their long axis to form an organized mesostructure. The different aggregation ability of the magnetic fluid particle is responsible for the variation of the optical properties under different magnetic fields and for different polarization of the incident light. It is noteworthly that the magnetically modulated refractive index of the magnetic fluid film could have great potential in electro-optical applications. In particular, according to the experimental results, we believe that the fluid films that we are proposing, thanks to the optical responses and the relative times, is a very good candidate to design Fiber Optical Sensors (FOS) for magnetic fields.

SOI (silicon-on-insulator)-based micro-resonator is the key building block of silicon photonics, which is considered as a promising solution to alleviate the bandwidth bottleneck of on-chip interconnects. Silicon-based sub-micron waveguide, microring and microdisk devices are investigated in Institute of Semiconductors, Chinese Academy of Sciences. The main progress in recent years is presented in this talk, such as high Q factor single mode microdisk filters, compact thirdorder microring filters with the through/drop port extinctions to be ~ 30/40 dB, fast microring electro-optical switches with the switch time of < 400 ps and crosstalk < -23 dB, and > 10 Gbit/s high speed microring modulators.

Silicon photonics can found applications in optical interconnects and optical signal processing. Recent years, silicon photonics was developed rapidly. In this paper, we report our research work on silicon photonics. Based on the standard CMOS foundry, we studied the silicon waveguides and related photonic components.

For the SOI-waveguide directional coupler (WDC), optical access loss (OAL) and polarization dependence (PD) are two critical performance specifications which seriously affect the adoptability and deployment of a device, including optical on-chip loss (OCL), polarization dependent loss (PDL) and extinction ratio of a 3dB-coupler based device. In this work, using a commercial software tool - FIMMPROP, the performance of an SOI-WDC is simulated. Simulations find that the curved waveguides for the turning sections of a 3dB WDC not only enlarge the footprint size, but also seriously deteriorate the device performance. For instance, the two curved waveguide sections of a WDC induce an unpredictably large change in the 3dB-coupling length, increase an OAL of 0.4-0.9dB, and seriously deteriorate the PD, and these performance changes radically depend on rib size. After a corner-turning mirror (CTM) structure is introduced to a 3dB SOI-WDC, the experiments show both the footprint length and 3dB-coupling length are unchanged, the OAL of the 3dB coupler is only 0.5dB which is close to the simulation value. Therefore, for a 3dB-coupler based Mach-Zehnder interference (MZI) structure, the OCL will be controlled to be <1.0dB in device design and will not depend on rib size.

The pump-to-Stokes RIN Transfer and its impact on output characteristic in silicon Raman lasers are numerically investigated. The result shows that RIN transfer strongly influence on the output RIN of the chip scale silicon Raman laser. High-frequency RIN transfer show intense oscillation at about10⁹Hz, which is several orders higher than that in Raman fiber laser (about10⁴Hz ). We also find that RIN transfer reaches a peak value at resonance frequencies and decreases with the increasing the free carrier lifetime.

This paper illustrates the design and fabrication of wavelength filters using resonant cavity which is constructed out of a phase shifted vertical side wall grating. The resonant cavity is analyzed as a Fabry-Perot resonator and the variation in cavity quality factor (Q) and transmission with respect to various grating parameters is studied. It is observed that a high Q-factor together with a high transmittivity can be obtained for this wavelength filter through optimization in grating length and reduction in the out of plane loss. Multiple phase shifts are applied in the grating to get a coupled cavity configuration so that channel isolation and spectral shape is improved. The channel wavelengths in a DWDM ITU grid C band (100GHz spacing) is simulated by varying the phase shift length of the gratings and good channel isolation with constant Q -factor and transmittivity is observed for the spectrum. The paper also explains the effective fabrication process flow for this structure on a silicon wafer through e-beam lithography and Reactive Ion Etching (RIE).

In this paper, we calculate the thermal dissipation in semiconductor Optical Amplifier. We investigate the effect of the material composition, the number of wells, the type of structure (Buried or Ridge), on the thermal resistance of the component and try to extract some rules towards minimization of temperature elevation. An increase in the number of quantum wells within the same type of structure increased the thermal resistance but not significantly. The type of source, a concentrated single source or a distributed in the different wells, does not play a significant role in the thermal resistance of a structure. The difference between Pside up or down mounted device is clear and well known. The variation of Separate Confinement Heterostructure has, in both the P_up and P_down structures, almost no effect on the R_th. The influence of heat repartition inside the wells has been evaluated. Finally the overall heat dissipation in the optical module is calculated; the objective is to the decrease the overall electrical consumption keeping the performances required by the application.

An Ytterbium-doped double-cladding fiber laser is demonstrated. The threshold of the pump power is about 1.1W. The maximum output power is 9.9W at the wavelength of 1045nm when the pump power is 15.3W. The slope efficiency is around 70%. We discuss an exact numerical model, with a shooting method to solve the power steady-state equations. Numerical results about the output power as a function of the pump power are in good agreement with measurements.

Optical splitter is one of most typical device heavily demanded in implementation of Fiber To The Home (FTTH) system. Due to its compatibility with optical fibers, low propagation loss, flexibility, and most distinguishingly, potentially costeffectiveness, glass-based integrated optical splitters made by ion-exchange technology promise to be very attractive in application of optical communication networks. Aiming at integrated optical splitters applied in optical communication network, glass ion-exchange waveguide process is developed, which includes two steps: thermal salts ion-exchange and field-assisted ion-diffusion. By this process, high performance optical splitters are fabricated in specially melted glass substrate. Main performance parameters of these splitters, including maximum insertion loss (IL), polarization dependence loss (PDL), and IL uniformity are all in accordance with corresponding specifications in generic requirements for optic branching components (GR-1209-CORE). In this paper, glass based integrated optical splitters manufacturing is demonstrated, after which, engineering-oriented research work results on glass-based optical splitter are presented.

Multimode Interference (MMI) based devices are widely used due to excellent performance. Here in this paper, a 1×2 multimode power splitter based on MMI is designed using three-dimensional beam propagation method (3D-BPM), and then fabricated in glass using the Ag+-Na+ ion-exchange technique. The width of the input and output multimode waveguides was 50μm and they were tapered to 75μm at the interface to the MMI region. The MMI region was also quadratically tapered .First, Ag+-Na+ ion exchange was run in nitrate melt at 350°C.Then an electric field was applied at 300°C so that the silver ions continued their migration award. Under the wavelength of 1550nm, the measured results showed that the propagation loss of multimode straight waveguide can be lower than 0.31dB/cm, and the insertion loss and uniformity of the splitter were 4.28dB and 0.21dB, respectively. Parameters of the fabrication process and structure of the device can be optimized to improve the performance of the device.

In this work, we report a novel waveguide structure that hybridizes the conventional dielectric waveguides with novel metal/dielectric plasmonic waveguides by incorporating the former inside the dielectric part of the latter. As a result, the strongest field in the waveguide locates at the center of the guide instead of the metal/dielectric interfaces, which can significantly reduce the propagation loss, and meanwhile offer excellent confinement of the plasmonic lightwave. Theoretically the inside wave mode is to be shown a hybrid plasmonic-optical mode. We further analyze the mode properties of such waveguides with various structure dimensions, and demonstrate its wave propagating characteristics with numerical simulations. The theoretical study suggests that such waveguides are promising for ultra-compact integration of lightwave circuit. Additionally, fabrication of such waveguides is compatible with current micro/nanofabrication technologies.

Mach-Zehnder interference (MZI) construction is broadly exploited to implement optical switches and modulators in the field of integrated optical/photonic technology. Silicon-on-insulator (SOI) waveguides have been increasingly developed to implement highly integrated photonic devices and systems. In this work, for the SOI-waveguide MZI-type electro-optic (EO) modulated devices with free-carrier dispersion (FCD) effect, the FCD-induced extra optical absorption (EOA) loss and its negative impact upon the device performance are studied. An intrinsic limitation to this type of device is found to be the tension between the EOA loss and the interaction length for a half-wave modulation. The numerical calculation and professional software simulation show the EOA loss of <1.0dB determines an interaction length of 4-mm. The performance decay processes of both EO switch and modulator due to the modulation-induced EOA loss are modeled. The numerical calculation shows the optical on-chip (OC) loss is 1.0dB and the isolation between two outputs is 21dB for the EO switch, while for the EO modulator the OC loss is 1.0dB and 2.5dB at the off- and on-state, respectively, and the extinction ratio only approaches 20dB. The negative influence of this intrinsic limitation to the bandwidth of EO modulator is also analyzed.

Silicon-based electro-optic modulator is a key device that used to implement optical interconnections. The paper is attempt to analyze the Silicon-on-insulator (SOI ) structure characteristics of resonator, according to the transfer function. The spectra response of Single Micro-Ring (SMR) and Double Micro-Ring resonators (DMR) with a ridge cross section on silicon was discussed emphatically. The 3dB bandwidth and the coupling coefficient affection on it were calculated and compared. The relationship between the characteristics of resonators the coupling coefficient was analyzed. The commercial software Rsoft was used to simulate the figures of SMR and DMR respectively. The simulation results show that the 3dB bandwidth of DMR can be achieved much narrower than that of SMR through the optimization design of the structural parameters. And the filter response line is sheerer for the DMR.

Dichroic beam combiner is the kernel technology of the dual mode guiding simulation system. Based on the photonic band gap structure of one-dimensional Photonic crystals, a new method of designing a diachronic beam combiner is proposed in this paper, through which mid-IR region high reflection mirror coating is designed and calculated by using plane-wave expansion method. Simple construction, combination of broad wave band beams in 2D and wide-angle is realized, and polarization of off-axis incident beams is prevented. The analysis of infrared reflectivity and radio frequency transmission rate demonstrates that this new method can perfectly satisfy the demand of design.

We analyze the nature of modal cutoff in photonic crystal fibers which core is filled with liquid crystal. The radius of effective modal fields is used to determine the cutoff wavelength and fiber dimension between the regimes with single-mode and multi-mode operations in the photonic liquid crystal fibers (PLCFs). After calculated the normalized frequency V, we establish the parameter subspace in photonic liquid crystal fibers (PLCFs) are single mode.

We report a new configuration of logic gates based on single hexagonal-lattice PCRR composed of cylindrical silicon rods in air. Two types of inner ring including regular hexagonal and circular are numerically discussed by using 2D finite-difference time-domain (FDTD) technique. The impact of surrounding periods and scatterers like size and relative phase at each input port was investigated. The logic '0' and '1' of hexagonal ring can be defined as less than 17% and greater than 85%, respectively, much better than early reported square-lattice results. The simulation results also proved that photonic logic gates based on this new single PCRR can really function as NOT and NOR gates, respectively. These findings make PCRRs potential applications for all-optical logic circuits and ultra-compact high density photonic integration.

Based on ultrahigh-order modes in symmetric metal-cladding waveguide with millimeter scale, a new oscillating wave sensor is investigated to measure minute changes in various parameters of aqueous solution. In the proposed geometry, the sample acts as the guiding layer where oscillating waves propagate. Owing to the concentrated power in the sensing region and the use of the very sensitive ultrahigh-order modes and the unusual large Goos-Hänchen shift, it is demonstrated both theoretically and experimentally that its sensitivity is enhanced by one order of magnitude than that of evanescent wave sensor.

We added excess silicon into erbium silicate to form silicon-rich erbium silicate (SRES) films on p-type silicon substrates by magnetron sputtering technique. After annealed at 850°C in N₂, the element contents of erbium, silicon and oxygen in the films were estimated by Rutherford backscattering spectroscopy. Room temperature Er³⁺ 1.54 μm electroluminescence from the structure of indium tin oxide (ITO)/SRES/p-Si has been studied. Its electroluminescence intensity can be markedly enhanced by optimizing the excess Si content in the SRES film.

In this paper, an accurate Fourier Optics method of designing AWG demultiplexer based on high-index-contract Silicon-on-Insulator (SOI) materials is presented. The typical SOI photonic wire waveguide has a cross section of 400×340nm² satisfying single-mode condition, and operating central wavelength is 1.5500μm. A three-stigmatic-points method is also applied in order to improve the accuracy, considering the aberration theory. Furthermore, our AWG has another important characteristic--the flat field of the output ports. In the example presented here, we design a 1×256 channel AWG with 0.1-nm channel spacing. The simulation result shows that the insert loss is almost 0dB for the central and peripheral output ports as well, representing a good uniformity. Meanwhile, the crosstalk to the adjacent channel is 14.4dB. Free spectral region (FSR) equals to 30nm as designed.

It is necessary to take some research into the thermal analysis of polymer waveguide ,which is important to the interconnection among chips ,in order to guide the improvement of the technique of conventional integration and make it more advanced. In this paper, we are successful in making a polysiloxane rib waveguide which is 21 cm long like a line, and laser can propagate along the rib area directly. In order to take a research in the compatibility between this waveguide and the integration technique, we analyze the thermal characteristics of the waveguide applying the ansys software. We make the analysis model and meshing it. We also set the boundary conditions, and take some research in the thermal characteristics of the waveguide and its thermal distribution of its cross section according to the time. At last , we get that the instantaneous high temperature can not infect the core layer. We also get that the temperature as high as 400 °C can not lasting more than 0.035 seconds. Those all conclusions are useful to the integration technique.

A Faraday-Fabry-Perot (FFP) cavity, composed of an Fabry-Perot (FP) cavity and a piece of Faraday magneto-optical material, is presented. The principle of FFP cavity and its polarization modulation effect are described by use of optical matrix analysis. The result shows that the Faraday rotation is able to be magnified by more than two orders of magnitude in resonant FFP cavity, while different elliptically polarized lights are obtained in non-resonant cavity. Furthermore two novel applications, that is, optical isolator based on passive FFP cavity (FOI) and Faraday-Zeeman dual-frequency laser (FZDL) based on active FFP cavity whose eigen modes operate as circularly polarized lights and whose frequency difference can be adjusted continuously by magnetic field, are introduced. The principles, typical parameters and performance characteristics are analyzed in both applications.

Tree-type network composed of optical splitters and optical combiners, according to the corresponding link rule, plays an important role in the all-optical communication and optical information processing. Based on the matured polarization control technology to realize routing and switching of signal beams, a novel tree-type interconnection network using phase spatial light modulator (PSLM), polarizing beam-splitter (PBS) and mirror, is proposed, including 1×2, 1×4, and 2×1, 4×1 switch elements. It is able to perform any arbitrary interconnection pattern, which has the advantages of compact in structure, efficient in performance, small size, and polarization-independent due to exploiting the building block pattern. The theoretical analysis shows the functional experimental prototype with large number of input/output ports should be helpful in the optimization and design of large-scale optical switch matrix.

A plasmonic Bragg reflector with rectangular-shaped transmission spectrum based on MIM (Metal-Insulator-Metal) waveguides is proposed and theoretically analyzed in this paper. As the MIM waveguide structure is treated as a cascade structure of multi-F-P cavities and by use of Transfer Matrix Method (TMM), the property parameters of the reflector is related to the structure parameters of grating, so that the performance index of reflector can be optimized. As an example, a wide bandgap reflector is designed by this method, the center-wavelength of it at 1550nm, the full width at half maximum (FWHM) of it at 640nm and the center-transmission of it approaching zero.

We proposed and demonstrated an all-fiber laser to generate cylindrical vector beams at 1030 nm. The cylindrical vector beams were obtained by exciting high order mode operating in the few-mode fiber inside the laser system, which was implemented through adjusting the angle and transversal dimension of a couple of fiber collimators. The radial and azimuthal polarization beams can be switchable conveniently just by applying twist and pressure to the few-mode fiber.

We develop a simple iterative model to simulate a laser with homogeneous gain and intensity dependent loss. Simulation results show that a laser with homogenous gain can operate at multiple wavelengths if the intensity-dependent loss exhibits saturable transmitter characteristics. Our results also show that for nonlinear losses that have both saturable transmitter and saturable absorber characteristics, such as arises from nonlinear optical loss mirrors (NOLM) or nonlinear polarization rotation (NPR), the multiwavelength output power spectrum can become very flat. The laser can also exhibit periodic and chaotic behaviors. We find that the same theoretical model can also be used to describe multipulsing dynamics of mode-locked lasers when the cavity energy increases. Near the multi-pulsing transitions, both periodic and chaotic behavior can be observed as operating states of the laser cavity. Our iterative model provides a simple geometrical description of the entire multi-pulsing transition behavior as a function of increasing cavity energy. The model captures all the key features observed in experiments, including the periodic and chaotic mode-locking regions, and further provides valuable insight into laser cavity engineering for maximizing performance.

In this paper, we propose an ultrashort pulsed waveguide laser using carbon nanotube saturable absorber integrated with gain medium, in which the carbon nanotube saturable absorber is directly sprayed on the Er-Yb doped phosphate glass ion-exchange waveguide, a linear cavity is chosen. The waveguide structure and lasing performance of the proposed waveguide laser are analyzed theoretically. The effects of the nonlinear coefficient and cavity dispersion on the output characteristics of the ultrashort pulsed waveguide laser are discussed.

The variable separation method and coordinate transformation is presented for solving the refractive index distribution of the regular hexagon GRIN lens. Through the software programming, the exact solution of the refractive index distribution is proved by the correctness. The result is obtained for the manufacture of imaging systems and characteristics. The model can be extended to solve the even-numbered polygon edges in the positive refractive index distribution of GRIN lens.

DFB Fiber laser based sensors, including strain sensing, temperature sensing and acoustic sensing, have attached a lot interests because of high performance and small size.We demonstrate a simple DFB fiber laser hydrophone and its demodulation is realized by a simple intensity based scheme. The reasons of the intensity modulation of DFB fiber laser, including gain demodulation, feedback effect, and polarization demodulation, are discussed in detail based on rate equations. The frequency response of the DFB fiber laser based hydrophone is measured in an anechoic water pool and compared with a referenced B&K8104 hydrophone.

We have theoretically investigated the polarization properties of a single-mode photonic crystal fiber (PCF), which is pulsed one-side by CO₂ laser resulting in partial air-holes collapse and deformation. The CO₂ laser micro-fabrication is a common way in PCF post-processing, which is used widely both in writing fiber gratings on PCFs and making optical components such as PCF polarizers. A series models with different valley depth which is due to the collapsed air-holes have been simulated by using a full-vector finite-element method (FEM) with a perfectly matched layer (PML). The theoretical results show that the deeper valley causes a larger insertion loss, at the same time, leading a larger polarization dependence loss (PDL). This research provides an insight into the side-pulsed PCF as well as a guidance on the experiment of CO₂ laser micro-fabrication on PCFs.

We designed and experimentally reported modified potential InGaAs/InAlAs coupled quantum wells. In this structure, a large blue shift of the absorption edge of more than 35 meV is obtained at a reverse bias of -4 V. This predicts that a large negative electrorefractive index change can be achieved at longer wavelength region of the absorption edge.

We have studied the effect of buffer layers on the performance of poly(3-hexylthiophene-2,5-diy1) (P3HT):C61-butyric acid methyl ester (PCBM) bulk heterojunction solar cells. We proved that depositing a thin pentacene layer between metal cathode and P3HT: PCBM blend and introducing a thin P3HT layer between ITO and photoactive layer, would improve the power conversion efficiency of polymer bulk heterojunction solar cells when compared with the cells without the buffer layers. In the study, the buffer layers increased short circuit density (Jsc) and open circuit voltage (Voc) under the illumination by white light from a solar simulator with an incident intensity of 100mW/cm2. The thin pentacene layer as a cathode buffer layer modifying the contact between the active layer and the cathode, the thin layer of P3HT as a anode buffer layer enhancing the electron blocking ability were responsible for the improvement on the performance of photovoltaic device.

A electric field technique was developed to fabricate 1×4 buried channel waveguides on optical glass. The 40V voltage was applied on the glass to accelerate the exchange of sodium ions in the glass and cesium ions in the salt melt. As a result, the optical loss of 0.1dB/cm was obtained for channel waveguides of 20μm depth with the 1.550μm laser, and a 3D buried channel waveguide is produced by the non-uniform field ion exchange under 1μm height inclined on glass.

Quartz crystal is a good piezoelectric crystal and it can be used as substrate of surface acoustic wave (SAW) devices. How to cut the substrate crystal is important in design of the SAW devices, and the optimum cut direction is determined by the direction of the largest electromechanical coupling coefficient. In this paper, SAW basic equation group strengthened by piezoelectric effect and boundary condition equation group including mechanical boundary conditions and electric boundary conditions are deduced. The electric boundary conditions have two kinds: free boundary condition and short-circuit boundary condition. Two kinds of SAW velocities using the two kinds of electric boundary conditions are systematically calculated for the quartz crystal respectively in decoupling of yz plane. The SAW velocities are calculated using a circle iterative method, which calculation velocity is quick and calculation precision is high. Electromechanical coupling coefficient is calculated using these two SAW velocities in yz plane of the quartz crystal. Calculation results indicate that the maximum electro-mechanical coupling coefficient is 0.2885 at direction, which makes an angle of 73° with y axis, in yz plane of the quartz crystal. The calculation results lay a solid foundation for design and manufacture of the SAW devices.

We proposed a new channel drop filter (CDF) based on race-track photonic crystal ring resonator (PCRR) composed of square-lattice cylindrical silicon rods in air. Two representative scenarios, parallel and perpendicular, related to the direction of race track and bus channel waveguide, are comparably studied by using 2D finite-difference time-domain technique. A good set of parameters with adequate modal spacing can be determined by adjusting the amount and size of scatterers. By optimizing the relationship among surrounding periods, race-track ring size and coupling strength, more than 150 spectral quality factor and 93.9% dropped efficiency can be achieved at 1370-nm channel for one single race-track PCRR. These findings enhance and enrich the PCRRs as an alternative to current micro-ring resonators for ultra-compact WDM components and high density photonic integration.

The built-in electric fields formed in varied doped GaAs photocathode may promote the transport of electrons from the bulk to the surface, thus the quantum efficiency of varied doped cathode can be enhanced remarkably. But the really reason of this enhancement, which may be either the increase in the amounts of electrons reaching the surface, or the increase in the energy of the electrons arriving at the surface, is not clear at present. In this paper, the electrons energy distributions in varied doped photocathode and uniformed doped photocathode before and after the electrons escape from the cathode surface were analyzed, and the amounts of the electrons escaped from the surface in different case were calculated for the two kinds of photocathode. The analysis results according to the experimental result indicate that, the varied doping structure may not only increase the amounts of the photoelectrons arriving at the surface, but also cause an offset of the electrons energy distribution to high energy, and which is the root reason for the enhancement of the quantum efficiency.

Transparent thin films are manufactured by PLD (pulsed laser deposition) in different oxygen pressure. The various property of samples is measured by Atomic Force Microscope (AFM), X-ray diffraction (XRD) and optical transmission spectrum. All samples retain the original structure in wurtzite lattice by XRD, there is not being of metallic cobalt or other impurity phase with the limit detection. The surface morphology of the films observes the smoother than that in undoped ZnO thin film. The transparency of thin films has altered greatly with the different oxygen pressure or not by PLD, which is shown that the oxygen pressure has impacted on the transparency of the film and surface morphology. And UV-visible spectra fully have been demonstrated the presence of Co²⁺ to substitute for Zn²⁺ in the films with the different oxygen pressure.

A broadband waveguide amplifier based on long-period waveguide grating and multilayer medium thin film filter is proposed. The long-period waveguide grating is directly written in the Er-Yb codoped phosphate glass waveguide by using UV-written technology and the multilayer medium thin film is coated on the output interface of the waveguide. The light transmission characteristics of the proposed filter are analyzed theoretically. The effects of the transmission spectra of the filter on the flattening gain spectrum of Er-Yb codoped phosphate glass waveguide amplifier are discussed. It's demonstrated that the flatness of below 1dB is achieved over a bandwidth of ~ 30nm.

We proposed a novel optical fiber hydrophone based on the feedback effect of a composite cavity optical fiber laser (CCFL) and a corresponding intensity demodulation scheme. The feedback of the CCFL is introduced by the end face reflection of the single mode optical fiber. The intensity modulation of the CCFL is caused by the modulation of the CCFL feedback.

The Eu(DBM)₃phen-doped polymer optical fiber slice was prepared, and the population of Eu³⁺ ion was up to 1.0 wt.-%. The chromatic dispersion and absorption characteristics of fractal clusters of Eu³⁺ ions in Eu(DBM)₃phen-doped POF slice were explored. The dielectric components homogeneously and inhomogeneously doped circumstances of this kind of POF slices were studied and their transmissions were analyzed and compared theoretically. Using near-field scanning optical microscopy (NSOM), the near-field light intensities of this kind of POF slice were measured, and agreement was obtain between experiment and theory. The result indicates that the clustering in this kind of POF is not obvious.

For the long wavelength infrared detection, HgCdTe (MCT) photoconductive devices are selected as the core of next-generation meteorological because of its mature fabrication technique and stable performance. During the assembly process, an innovative multilayer ceramic board providing mechanical support is designed as the electrical interconnection between MCT chips and external circuits for cryogenic application. Furthermore, due to its brittleness, long linear MCT device is normally glued to sapphire substrates on the multilayer ceramic board with cryogenic glue. Thus, it can be seen clearly that the assembly structure is a multilayer configuration which comprises various kinds of materials, including ceramic broad, sapphire, MCT and glues. As a result, the difference in Thermal Expansion Coefficient (TEC) between the layers could create the potential to introduce thermal stress at working environmental temperature (approximately 70K), which could result in device performance degradation, even die crack. This article analyzes the thermal stress between long linear MCT devices and a multilayer ceramic board by using Finite Element Method (FEM). According to analysis results, two factors are revealed as the most significant causes for introducing thermal stress: one is the sapphire substrate thickness; the other is the parameters of various materials, for instance Yong's modulus and TEC. Since the structure of MCT detector is determined by system requirements and is under the limitation of manufacture technology, this article reveals two effective approaches to reduce the unavoidable thermal stress: first, choosing the appropriate thickness of ceramic board which is made by Al₂O₃; second, adding another metal cushion Invar. With the above considerations, the distribution of thermal stress is simulated using FEM under different parameter conditions. Based on the results of simulations, an optimal design of package structure which could improve the reliability of linear MCT with minimum thermal stress is demonstrated.

The far-field distribution of single-mode fiber is studied; the Gaussian approximation for it is analyzed based on the characteristic of beam propagation factor and then its rationality is explained. Through researching the matching efficiency between the far-field and Gaussian field, a new definition of divergence half-angle is presented according to the maximal matching efficiency method; furthermore, a formula of the maximal matching efficiency divergence halfangle as function of normalized frequency is given.

Uncooled focal plane array (UFPA) has broad application prospects in civilian and space because it's cheaper, more compact and high reliability. Many research institutes and companies have carried out the research of uncooled focal plane array. This paper shows a vacuum package design of UFPA, and its architecture will be given. The assembly is an all-metal vacuum package, which has been proven rugged and reliable. Out-gassing, permeation, evaporator, and air leak are factors to reduce the component vacuum lifetime. Theoretical analysis shows that material out-gassing is the main factor of pressure rise inside package. Theoretical analysis and calculation show that designed metallic structure can meet the need of 10-years life.

In this paper, numerical simulation and analysis of the sensitivity of Strength-based Optical Fiber Sensors (SOFS) have been reported .The results simulated show that suitable operating point can improve sensitivity of the sensing system greatly even up to 3.6%. This conclusion can provide theoretical support for optimizing actual strength-based optical fiber sensors with higher sensitivity.

The electro-holographic optical switch based on the quadratic electro-optic effect in paraelectric photorefractive crystals requires driving signal of fast pulse. The pulse rise/fall time and voltage are 10^-10-10^-8s and 10²-10³V, respectively, depending on the applications. A pulse control signal generator for the electro-holographic optical switch was designed and simulated. Considering the integration of pulse signal generator and the switch, the circuit employs three stages compact Marx generators utilizing parallel avalanche bipolar junction transistors series operated in the avalanche mode in each stage. These transistors and the crystals are mounted on printed circuit board. According to the simulated results, the output voltage ranged from 1.2kV to 1.5kV. The rise/fall time of this pulse is less than 3 nanoseconds. The pulse width is 20 nanoseconds, and trigger delay is about 1 nanosecond. The repetition rate is less than 50MHz which can be increased by reducing the pulse width of the trigger. The simulation results indicate that the pulse control signals from the designed generator can match the application of electro-holographic optical switch well.

This paper presents an improvement approach to realize tracking on smooth glass surface based on subjective speckle. The scattering mechanism on glass surface is analyzed and the affection on tracking precise and range for tracking with subjective speckle is researched. The speckle captured by CCD just from the upper surface of the glass is achieved by grazing incidence of the laser beam and the noise mixed with the signal is eliminated by a barrier above the surface. Based on the apparatus of subjective speckle tracking, the speckle contrast is improved from 0.25 to 1.25 by non-Gauss effect and the range of the tracking has been increased from 200 μm to 400 μm compared with the objective speckle method on the same condition.

The squeezed photonic crystal fibers have attracted significant attention, which is a kind of photonic crystal fiber with squeezed lattice or elliptical air holes in cladding. So far there is no a universal concept to describe the squeezed degree. We introduce the concept of the modified squeezing ratio to describe the squeezed degree of the squeezed photonic crystal fibers, and then present a corresponding model. Using this model, we investigate the influence of modified squeezing ratio on the birefringence characteristics of photonic crystal fibers based on the supercell lattice method. Furthermore, it is reported for the first time to our knowledge that the complex influence of the lattice squeezing and the elliptical air holes on the birefringence is discussed.

Large core and long multimode optical ridge waveguides for optical interconnection are fabricated by the soft molding and simple replication with the Polyvinylidene fluoride (PVDF) and the polysiloxane materials. Both polysiloxane materials used for the core layer and the cladding layer are low loss and high temperature stable materials. The fabrication processes is based on transferring patterns of waveguides core layer to cladding layer using an elastomeric PVDF mold. The length of fabricated waveguides is more than 20cm, and the fabricated waveguides shows the fine performance when light pass through waveguide. The optical propagation loss of waveguides is 0.14dB/cm measured by the cutback method and 0.13dB/cm measured by digital scattering method at 632.8nm. The fabricated multimode waveguide fulfils basic requirements for a successful development of large size electrical optical circuit board production

In this paper, a multi-wavelength fiber laser based on cascaded semiconductor optical amplifier (SOA) was proposed by using a high birefringence fiber loop mirror (Hi-Bi FLM) as wavelength filter. The 0.6nm homogeneous broadening line-width of the SOA enabled laser oscillation with WDM ITU-grid spacing possible. The output 16 wavelengths in C+L band spacing on 100GHz were obtained. By using passive single-pass optical feedback, the power-equalized oscillating spectrum is broadened so that simultaneous oscillation of 27 lines spaced on 100GHz was achieved. The lines were power-equalized to within ±3dB and the extinction was better than 25dB. An active single-pass optical feedback mechanism was also used to further equalize the output power. Then the 18 lines within ±1.5dB were obtained with extinction better than 30dB.

For the using of space lab, a miniaturized low-power light-emitting diode-induced fluorescence (LED-IF) detector for capillary electrophoresis was constructed and evaluated. In this work, a more efficient exciting light source based on Led was developed and a convenient detect plate was produced to release the problem of focusing LED light into a spot with a diameter less than 100μm.besides these, all closed structure was used to avoid light cluster, and photomultiplier tube was used to be detector.for the reason of power and flexible, the ultra-low Power MCU(MSP430F449) was used to complete signal processing. The system exhibited the result in the concentration range of 1.0×10^-6 to 1×10^-7Mol/L.

Multiphoton upconversion luminescence (UL) properties from the Yb³⁺-sensitized Tm³⁺ ions in nanocrystalline yttria host were studied experimentally under 973 nm laser excitation. Bright pure blue luminescence in the visible spectral region was performed even at low pump excitation level. An interesting chromatic switching behavior was observed for the near-infrared and blue spectral bands at room temperature, showing a pump intensity-controlled emission wavelength switcher. The chromatic switching is intrinsically associated with the competition of two-photon UL and three-photon UL processes. Moreover, the wavelength switching of Stark emission of Tm^{3+ 1}G₄ state took place as the pump intensity rises enough. This phenomenon is attributed to pump induced photothermal effect changing the distribution of Stark level populations in Tm^{3+ 1}G4 energy state.

A broadly tunable erbium-doped fiber ring laser is investigated through theoretical modeling and experiment. A numerical model based on an iterative solution of propagation rate equations is used to analyze the dependence of laser output power on total intracavity loss and output couple ratio. The numerical results are in good agreement with the experimentally obtained data. The results indicate that minimization of the intracavity loss as well as optimization of the output coupling ratio is very important. A S+C+L band tunable range which covering 135nm is achieve. This fiber ring laser has a flat, stable output spectra and better than 60 dB signal-to-ASE-noise ratio.

A simple, cost-effective and switchable five-wavelength fiber ring laser based on a chirped moiré fiber grating (CMFG) and a wavelength-tunable Sagnac loop interferometer (FSI) filter is proposed and experimentally demonstrated. To serve as wavelength selective element, the CMFG possesses excellent comb-like filtering characteristics including stable wavelength interval and ultra-narrow passband, and its fabrication method is easy and flexible. The usage of the FSI filter helps remove the high-cost optical circulator and improve the output performance of optical signal-to-noise ratio from 50dB to 70dB. With this laser configuration, the output power fluctuation of each wavelength is less than 0.5 dB within a one-hour period, and the output power of different channels is almost identical (difference less than 1dB) within the tunable range.

A new design for polarization-insensitive silicon-on-insulator (SOI) arrayed waveguide grating (AWG) is proposed. In arrayed waveguide region, Si nanowire waveguides and slot waveguides are combined to adjust the optical path differences. For the slot waveguides, the refractive indices of the TE and TM polarizations satisfy n_TM>n_TE while in the Si nanowire waveguides n_TM<n_TE, so the refractive indices of the TE and TM polarizations are complementary in these two kinds of waveguides. By calculating the relationship of Si nanowire waveguides and slot waveguides' length differences, optimizing the structure of slot waveguides and choosing the appropriate diffraction order, central channel wavelength and channel spacing can both reduce the polarization sensitivity greatly. The design process is given in detail and the simulation results demonstrate that the AWG demultiplexer can meet polarization insensitive demand.

The all optical window equivalent-time sampling method based on symmetric Mach-Zehnder interferometer are present. A system model based on SOA dynamic model was founded to analyze sampling process. The pulse broadening in PIN and its response are discussed too. The evolution of sampling function due to control delay and width of control pulse are numerical calculated. Sampling error caused by ASE, noise of PIN and control pulse jitters are analyzed theoretically. This all-optical waveform sampling system with simultaneous submilliwatt optical signal sensitivity (20-dB signal-to-noise ratio) and subpicosecond temporal resolution is demonstrated. The results have shown that the SMZ sampler system combined with postprocess can monitor waveform with low error.

Testing device TST-05B, which is suitable for adaptability test of semiconductor devices, electronic products and other military equipment under the condition of the surrounding air temperature rapidly changing, is used here for temperature shock test.Thermal stability technology of thermoelectric cooler control circuit infrared sight under temperature shock is studied in this paper. Model parameters and geometry is configured for ADI devices (ADN8830), welding material and PCB which are used in system. Thermoelectric cooler control circuit packaged by CSP32 distribution are simulated and analyzed by thermal shock and waveform through engineering finite element analysis software ANSYYS. Because solders of the whole model have much stronger stress along X direction than that of other directions, initial stress constraints along X direction are primarily considered when the partial model of single solder is imposed by thermal load. When absolute thermal loads stresses of diagonal nodes with maximum strains are separated from the whole model, interpolation is processed according to thermal loads circulation. Plastic strains and thermal stresses of nodes in both sides of partial model are obtained. The analysis results indicates that with thermal load circulation, maximum forces of each circulation along X direction are increasingly enlarged and with the accumulation of plastic strains of danger point, at the same time structural deformation and the location of maximum equivalent plastic strain in the solder joints at the first and eighth, the composition will become invalid in the end.

Traditional glass-waveguide-based electric-field-assisted ion-exchange model is characterized by the product of voltage and time which is well known as the voltage model. In the voltage model, the modeling condition is mainly assumed to be with a constant voltage (or a constant electric field) and temperature is considered to be a constant, diffuse depth is mainly determined by voltage and time. However, our recent studies and experimental results show that there is a thermally-induced warming effect in the ion-exchange, which leads to a change of local temperature in the glass substrate which means the electrical current induced heating effect and the decrease of the local electrical resist with the increase of the local temperature. In this paper, we analyze the influence of the temperature variation and introduce a temperature-independent parameter to modify the traditional voltage model and solve the influence of ion-exchanging temperature variation. Experiment results show that the voltage model with the temperature-independent parameter modification is more applicable than the traditional one. We obtain a more precise result than traditional model in our experiment.

This paper proposes a circuit control method achieving the flat-top steep-edge response of photodetectors. The response is realized using three wavelength selective photodetectors and the circuit which consists of amplifiers, comparators and a AND gate. Two groups of experiments were carried out. In group 1, 0.5dB, 3dB, 20dB bandwidths are 2.76nm, 3.29nm, 4.58nm from 1546nm to 1549.3nm. In group 2, 0.5dB, 3dB, 20dB bandwidths are 3.19nm, 2.89nm, 3.06nm from 1554.8nm to 1557.6nm. The results of experiments show that the desirable flat-top steep-edge response can be gained and the response linewidth is adjustable by selecting different photodetectors, so that the requirement of the WDM system and the network can be met. The method is easy to realize with low cost and has wide application in optical measurements and optical processing etc.

An ultracompact triplexer based on a shift of the cutoff frequency of the fundamental mode in a planar photonic crystal waveguide with a triangular lattice of air holes is presented and optimized. Some defect holes are introduced to control the beam propagation. The radii of the holes are changed to realize it. The numerical results obtained by the finite-difference time-domain method show that the proposed triplexer with a total size 12 μm × 6.5 μm can separate three specific wavelengths i.e. 1310, 1490 and 1550 nm with the extinction ratios higher than -18 dB.

We design a rod-type drop filter (RTDF) in a two-dimensional photonic crystal (2D PhC) employing self-collimation (SC) effect. The perfect 2D PhC consists of a square-lattice of cylindrical silicon rods in air. The dielectric constant and the radius of host rods are ε=12.25 (correspondingly the refractive index n = 3.5) and r=0.40a respectively, where a is the lattice constant. In such a PhC, self-collimation phenomenon occurs for transverse-magnetic (TM) light beams with frequencies between 0.176c/a and 0.192c/a. The proposed RTDF based on a self-collimation ring resonator (SCRR) consists of two beam splitters and two mirrors. The performances of the SCRR are investigated with the finite-difference time-domain (FDTD) simulation technique. The calculation results show that the transmissivity spectrum at the drop port has nearly equal peak spacing which will decreases when the geometrical length of the SCRR is increased. Moreover, the full width at half maximum (FWHM) and thus quality (Q) factor of peaks can be easily tuned by changing the reflectivity of two beam splitters.

In this paper, 256×1 and 512×1 element linear InGaAs detector arrays are hermetic packaged. Some processes were studied, including the structure design, thermoelectric cooler (TEC) heat load performance test, TEC vacuum baking, the window sealing, the seam welding of the cover lid and shell, and so on. The results show that the cooling temperature difference of TEC can reach over 55 K at room temperature, and it decreases by about 0.51 K with each additional 50 mW heat load. TEC works well after 500 hours of baking at 120 °C. The leakage rate tests show the assembly is better than 10^-5 Pa.cm3/s.

A novel optical scanning device based on electrowetting micro-prism (EMPs) is proposed, to solve the problems of beam deflection controlling with laser line source . The basic beam control unit is made from EMPs, which including three kinds of immiscible liquids (water / oil / water),whith utilizing electrowetting modulation of liquid contact angle in order to mimic the refractive behavior for various classical prism geometries. Through the electro-wetting effect, the beam deflection angle of the liquid prism can be adjusted about -15 ° ~ 15 °continuously in a specific voltage range (30 ~ 110V).And compared to other electronic control deflection, this device has great deflection angle, whith exceeding the continuous steering angles demonstrated for optical phased-array technology. At the same time, as the devices become smaller in size ,its switching response speed can be much less than ms. This device will help us study robust Fresnel and phased-array optics.

A novel silica-waveguide integrated acoustooptic frequency shifter (AOFS) with high diffraction efficiency is proposed for an optical wavelength of 1.55μm in this paper. Choose tapered silica waveguides fabricated on silicon substrates by PECVD and C-axis oriented ZnO piezoelectric films deposited using RF-sputtering as the interdigital transducer for the excitation of SAW. The interdigital Al electrodes are located at the interface between the nonpiezoelectric substrates (SiO₂) and the ZnO piezoelectric films, that is, ZnO/IDT/SiO₂ structure; when the ZnO films thickness h and SAW's wavelength Λ satisfy the relation h/Λ=0.4~0.5, electromechanical coupling coefficient of the interdigital transducer achieves the maximum value 17%. Diffraction properties are simulated and analyzed using beam propagation method (BPM) and AO interaction area is well-designed in order to obtain optimum interaction characteristics. The results show that a diffraction efficiency of approximately 70% can be obtained.

Temperature dependence of dispersion of G.652 fiber is experimental studied. The dispersion and dispersion slop variations over a temperature rang of 80°C, from -20°C to 60°C are measured. The effects of temperature dependence of dispersion on 80Gbit/s 100km OTDM system is experimental studied. Eye diagrams ascribed to the temperature of -20°C, 0°C, 20°C, 40°C, 60°C are demonstrated after 100km transmission link. The effect was also evaluated by BER curves. At last, dispersion thermal coefficient and dispersion slope thermal coefficient of dispersion compensating fiber were experimentally measured. The possibility of dynamically compensating chromatic dispersion and chromatic dispersion slope of G.652 fiber due to environmental temperature alterations by controlling the temperature of dispersion compensating fiber is proposed.

New light-emitting diodes (LED) structure constituted by the photonic crystal (PhC) is presented, and the effects of structure parameters are investigated. Relying on the results of investigation, the structure parameters of photonic crystal LED are optimized. By Using the FDTD algorithm, the enhancement factor of photonic crystal LED is calculated efficiently, and the optimum values of structure parameters are obtained after numerical optimization. With the optimum photonic crystal structure, the output efficiency of LED is enhanced.

Nano-Rare Earth Doped Fibers (NREDFs) have shown great application for optical fiber amplifiers, fiber lasers and sensors. The rapid development of fiber communication systems has a higher requirement on the NREDFs. Atomic layer deposition (ALD) is a chemical vapor deposition technique based on the sequential use of self-terminating gas-solid reactions. As a film deposition technique, ALD is known for its effective material utilization at low temperatures, accuracy thickness control, excellent step coverage, good uniformity and adhesion, good conformability. In this paper, ALD was used to fabricate high concentration alumina-erbium co-doped amplifying fibers. Based on Modified Chemical Vapor Deposition (MCVD) and ALD, using nanomaterials as a dopant, the alumina-erbium co-doped amplifying fibers were fabricated. The main advantages of this novel method include good uniformity, high dispersibility, and high doping concentration. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) images and X-ray energy dispersive spectroscopy (EDS) showed the physical and chemical features of the deposited film upon a porous silica soot layer. Photoluminescence (PL) and absorption spectra were used to characterize the optical properties. The fibers have high gain, low noise, high power and are independent of polarization, which make them desirable for fiber devices.

Dispersion and dispersion slope management is a problem for LEAF fiber, because LEAF fiber has a low dispersion but a significantly high relative dispersion slope. This article demonstrates a design of dispersion and dispersion slope compensator for LEAF fiber in WDM systems. It can compensate dispersion and dispersion slope respectively by combining broadband nonchannelized linear chirped fiber Bragg grating and a pair of nonlinear chirped fiber Bragg gratings, which can be inversely cascaded in a four-port optical circulator. The design can effectively improve dispersion linearity and increase dispersion matching ability of compensator, and a numerical experiment of compensating a 50-kmlong LEAF fiber in WDM system proves the feasibility of this approach.

A novel waveguide photodetector with flat-top and steep-edge response is proposed in the paper. The response is obtained by designing a racetrack resonator following parallel-cascaded two or three micro-ring resonators. Its maximum values of the quantum efficiency in bandpass are 99.8%; 0.5dB, 3dB, and 20dB bandwidth is 0.22nm, 0.39nm, and1.1nm for cascaded double structure and 0.28nm, 0.32nm, and 0.5nm for cascaded triple structure, both of which meet the requirements of WDM system. Compared with similar waveguide photodetectors and RCE-PD, this photodetector has high quantum efficiency, narrow line width and good flat-top and steep-edge response. The structure is compact and conducive to chip-scale integration.

For the thermal stability of mean wavelength of erbium-doped super-fluorescent fiber source (SFS), particularly, from a different viewpoint, we analyzed the variation of spectrum of SFS at different temperature and wavelength range. Firstly, the spectrum of a SFS at 10 °C is selected as a standard data (STDD), then at the different temperatures from -40 °C to +60 °C (10 °C per step), the spectrums subtract the STDD for the spectral temperature dependent instability. It is found that the variation of spectrum from short wavelength to long wavelength can be divided into three regions. In the middle wavelength region from 1540nm to 1565nm, the dBm values of the spectrum are decreased with increasing temperature, and with wavelength-flattened characteristics. On the other hand, at the short and long wavelength region, the dBm values of the spectrum change inversely with temperature, and the variations are larger than that of the middle region. Based on this characteristics, we design a new configuration of SFS, the mean-wavelength stability can be achieved 2.10ppm/mA and 1.75ppm/ °C in the range of pump current from 100mAto 250mA and in the range of temperature from -40 to +60 °C, respectively.

A specialty solid coupled (SSC) optical taper was introduced into the receiving termination for the rectilinear mobile wireless optical communication. Based on the curvature-shape matching relationship, the profile curve equation for SSC optical taper has been deduced. According to ray-tracing method, the optical coupling efficiency can be analyzed by the comparing the input and output light energy based on Fresnel reflection loss principle. The variation relationships among the taper length, shape factor, large end radius, small end radius, radial displacement, incidence depth, and coupling loss are analyzed. The results show that the theoretical simulation is in good accordance with the experimental data. The errors were also given. The coupling loss was less than 10dB as the radial displacements vary within 1.5 mm in x and y directions, respectively. For this experimental system, the receiving performance of SSC optical taper can satisfy the communication.

The modified base-catalyzed method and the seed growth method were employed to synthesize Eu(TTFA)₃-doped silica hybrid spheres. The transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and fluorescence spectrometer were used to characterize the doping particles. The results show that all kinds of as-prepared particles present the spherical morphology and the smooth surfaces. TEM images reveal that silica hybrid spheres are monodisperse and have an average diameter of sub-micron. FTIR analyses show that synthesized silica colloidal spheres mainly consist of 4-fold silaxone rings, including incomplete condensed silanols and incomplete hydrolyzed alkoxy groups. The hybrid spheres doped with Eu(TTFA)₃ prepared by different methods exhibit the characteristic photoluminescence (PL) of the Eu³⁺ ions and excellent narrow-line emission characteristic of Eu³⁺ ions. The existence of silica matrix has obious effect on the absorption properties of the ligand and slight effect on the emission properties of Eu³⁺.

The SiC/AlN bilayer thin films were grown by RF magnetron sputtering on the silicon(100)substrate, then were annealed from 500°C to 1000°C through the nitrogen gas. The optimum synthetic process was obtained, that is, the gas pressure was 0.5Pa, the flux of Ar was 60sccm, the sputtering power of SiC target was 150W for 1.5hr, while the sputtering power of pure Al target was 100W for 1hr, and the ratio of Ar to N2 was 2:1. Next the XRD, AFM and photoluminescence (PL) spectra of these films were measured with D/Max-γB X-ray diffraction and FL-4500 Fluorometric meter. Two PL emission peaks were observed respectively around 381nm and 400nm, and they came from the SiC particles and the carbon clusters respectively. The intensity of PL emission rises with the increasing of annealing temperature. The PL emission intensity of SiC/AlN bilayer thin film at 381nm is superior to SiC monolayer thin film while the that of SiC/AlN bilayer at 400 nm is inferior to SiC monolayer thin film. In addition to, the grain size of SiC/AlN bilayer thin film is finer than that of SiC monolayer thin film resulting from AFM morphology.

A tunable drop filter (TDF) based on two-dimensional photonic crystal (PC) self-collimation ring resonator (SCRR) is proposed. The PC consisting of square-lattice air cylinders in silicon has square-shaped equal frequency contours (EFCs) in the wavevector space at the frequencies between 0.172-0.188c/a for TE modes. The SCRR includes two mirrors and two splitters. The air holes inside the SCRR are infiltrated with a kind of liquid crystal whose ordinary and extraordinary refractive indices are 1.522 and 1.706, respectively. The effective refractive index n_eff of liquid crystal depends on the applied electric field. Simulated with the FDTD method, the transmission spectra at the drop port of SCRR are in the shape of sinusoidal curves with uniform peak spacing between 0.172-0.188c/a. Transmission peaks will shift to the lower frequencies when n_eff is increased. When n_eff changes from 1.522 to 1.706, the peaks will experience red-shift over 0.003c/a. So this SCRR can work as a tunable drop filter. For the operating wavelength around 1550nm, its dimensions are only tens of microns.

To improve the performance of GaAs NEA photocathodes, an exponential-doping structure GaAs material has been put forward, in which from the GaAs bulk-to-surface doping concentration is distributed gradiently from high to low. We apply this exponential-doping GaAs structure to the transmission-mode GaAs photocathodes. This sample was grown on the high quality p-type GaAs (100) substrate by MBE with p-type Be doping. We have calculated the band-bending energy in exponential-doping GaAs emission-layer, and the total band-bending energy is 59 meV which helps improve the photoexcited electrons movement towards surface for the thin epilayer. The integrated sensitivity of the two exponential-doping GaAs photocathode samples with different thickness reaches 1228uA/lm and 1547uA/lm respectively.

Based on semiconductor quantum dots and a tapered optical fiber, an optical fiber amplifier was proposed and studied in this paper. It was fabricated by coating PbS quantum dots doped sol-gel onto the tapered region of optical fiber. The PbS quantum dots were synthesized by colloidal method. The tapered optical fiber was made by using a standard single mode fiber through heating of CO₂ laser. With a Wavelength Division Multiplexer (WDM), a signal and a pump can be injected into the fiber tapered region and interacts with the quantum dots through the evanescent field so that the signal can be amplified. The optical gain was characterized and more than 10dB gain was obtained at 1310nm with only 1.6cm interacting length at 130mw pump power.

For the irregular shape of a fiber coupler, the coupling characteristics of it are usually studied in its different sections separately. It's necessary to build a united model to simulate the coupling characteristics of each section all together. Some appropriate geometrical configurations were employed, and modal field in a coupler was obtained by the weighted superposition of triangular distribution and Gaussian distribution, in the condition of lossless propagation. With that a united model was obtained by the variation technique, combined with the concept of local modes. It's a more refined model, which is available on condition that the core radius in the neck waist is around 1 μm and can provide theoretical guidance for the practical design and fabrication of a fused-tapered single-mode fiber coupler. In its effective area, there is a good agreement between the theoretical result and experimental result.

Compatible stealth of laser and infrared is an urgent demand of modern battlefield, but the demand is ambivalent for conventional materials. As a new type of artificial structure function material, photonic crystals can realize broadband thermal infrared stealth based on its high-reflection photon forbidden band. By forming a "hole-digging" reflection spectrum of doped photonic crystals, high transmittance at military laser wavelength of 1.06μm and 10.6μm can be achieved, so compatible stealth of laser and infrared can be achieved too. In this paper, we selected middle and far infrared-transparent materials, PbTe and Na₃AlF₆ as high refractive index and low refractive index material respectively, and designed a one-dimensional two-defect-mode photonic crystal based on principles of distributed Bragg reflector microcavity. And then its photon forbidden band was broaden to 1~20μm by constructing two heterojunction photonic crystals. The reflection spectrum and transmission spectrum of the photonic crystals were calculated by characteristic matrix method of thin-film optical theory. The calculation results show that the designed multi-cycle dual-heterojunction photonic crystal has a high spectral reflectance in the near, middle and far infrared band, whose spectral reflectivity is greater than 99% in 1~5μm and 8~14μm infrared bands, and spectral transmittance at 1.06μm and 10.6μm is greater than 96%. This will satisfy the laser and infrared compatible stealth in the near, middle and far infrared bands.

Quartz crystal has excellent piezoelectric properties, it can be used as substrates of surface acoustic wave (SAW) devices, for example delay line, filter, oscillator, convolver, acousto-optic (AO) device and so on. In this paper, Intrinsic SAW basic equation group and SAW mechanical boundary condition equation group are deduced from character equation of the crystal. Intrinsic SAW velocities are calculated using circle iterative method in three coordinate planes of quartz crystal systematically. Stiffness coefficient of piezoelectric crystal can be changed by piezoelectric effect and it is named as piezoelectric modified stiffness coefficient. Reciprocal velocity curves of quartz crystal in the three coordinate planes using the non-modified stiffness coefficients and the piezoelectric modified stiffness coefficients are drawn respectively. Configurations and periods of the curves are similar to projection figures of crystal lattice of the triangle crystal system in same coordinate planes. It means that there is internal relationship between the SAW properties and point group symmetries of the crystal. Research results lay a solid base for design and manufacture of the SAW device. It has theoretical significance and practical value.