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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705601 (2008) https://doi.org/10.1117/12.813263
This PDF file contains the front matter associated with SPIE Proceedings Volume 7056, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.
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Advances in Material Synthesis, Property, and Characterization I
Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705602 (2008) https://doi.org/10.1117/12.796582
Photoinduced birefringence in the film made of our azobenzene copolymer was demonstrated using blue excitation
laser beams and observed by a red probe laser beam. The birefringence values was obtained by polarimeter. The
polarization state of the probe beam was changed by the photoinduced birefringent film when the polarization
state is not agreed with the polarization state of the excitation laser beam. Then, a polarization component
orthogonal to the polarization state of the incident probe beam was observed. Using the principle, an image
pattern was recorded in the film using one-beam.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705603 (2008) https://doi.org/10.1117/12.793279
A stationary 2D axis-symmetric model able to evaluate the impurity distribution is developed by the finite element
method for single-crystal sapphire fibers grown from the melt by the edge-defined film-fed growth (EFG) technique. The
computations are carried out for two cases-one where the buoyancy is taken into account and the other where the
buoyancy is neglected-using different vertical temperature gradients kg in the furnace. The dependence of the impurity
distribution on kg and the Marangoni numbers Ma corresponding to the different surface tension gradients dγdT is
analyzed. Computations reveal critical Marangoni numbers Mac determined by the fluid flow behavior, and that a
smaller kg assures the best homogeneity of the crystal over a wide range of dγ/dT.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705605 (2008) https://doi.org/10.1117/12.791577
We present the results of the ab initio calculated electronic properties, first and second harmonic generation for
the AII BIV N2 (AII=Be, Mg; BIV =C, Si, Ge) compounds with chalcopyrite structure performed using the Linear
Augmented Slater-Type Orbitals (LASTO) method. The second-order optical susceptibilities as functions of
frequency for AII BIV N2 are also presented. Specifically, we study the relation between the structural properties
and the optical responses. Our electronic band structure and density of states (PDOS) analysis reveal that the
underestimate bandgaps of these chalcopyrite AIIBIV N2 are wide enough (from 4eV to 6eV), direct transition
and mainly located at Γ-point. Calcultion results show this new category wide-bandgap ternary nitrides has
potential applications in optoelectronics.
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Advances in Material Synthesis, Property, and Characterization II
Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705608 (2008) https://doi.org/10.1117/12.796912
Repetitive image reconstructions from a stratified reflection volume hologram have been shown, numerically and
experimentally, that are coded by wavelength references satisfied by Bragg condition. Many holographic layers are
recorded with red-sensitive photopolymers that are interleaved with slide glasses. The reflection comb responses have
been measured by a wide-tunable laser diode that agree fairly with a rigorous coupled-wave analysis (RCWA).
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560B (2008) https://doi.org/10.1117/12.793412
Sapphire (single crystal aluminum oxide) is a material commonly used in optical, electronic and chemical applications due to its material properties.
Sapphire is usually used for optical applications due to its ability to transmit from the Ultra Violet (UV) wavelengths into the mid Infra-red (IR) wavelengths. The transmission characteristics of the material is determined by various factors, however the impurities content seems to play a significant role. These impurities can either come from the growth process or from the starting raw material (commonly called crackle).
We studied the effect of impurities of the starting raw material with specific interest in hydrogen's effect on the optical properties (absorption, transmission) of sapphire crystals grown by different growth techniques.
We have characterized these growth techniques into two categories:
A)Large Thermal Gradient Method: (Czochralski (Cz), Edge Defined Film Fed Growth (EFG) or Stepanov)
B.) Low Thermal Gradient Methods (Kyropoulos, Heat Exchange Method (HEM))
We used the following starting raw materials ("crackle"):
a. Vernuil crystals produced by different manufacturers
b. High purity aluminum oxide powder
c. High Purity Densified Alumina (EMT HPDAR) produced by EMT, Inc thru their proprietary patented technology.
Through Nuclear Magnetic Resonance (NMR) analytical techniques, it was found that the hydrogen concentration is very high in Vernuil crystals or in aluminum oxide powder. Consequently, sapphire crystals grown using Vernuil starting material or aluminum oxide powder also have a very high Hydrogen content.
Utilizing the same NMR analytical techniques, EMT HPDAR starting material showed very low Hydrogen concentration. Thus, sapphire crystals grown from EMT HPDAR starting material has a very low Hydrogen content.
It was found that optical properties in sapphire crystals grown using EMT HPDAR starting material are more uniform and have higher transmission than in sapphire crystals grown using as starting material aluminum oxide powder or Vernuil crystals.
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Development in Component and Integrative Photonic Devices I
Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560E (2008) https://doi.org/10.1117/12.795250
In this paper, ultra low cross talk is achieved by using a resonant cavity at the intersection between two strip waveguides
formed in a square lattice photonic crystal structure (PhC). Two PhC structures are studied: one consists of cylindrical
rods and another consists of cubic rods. The Q-Factor of the cavity is changed by increasing the number of rods that form
the cavity and by decreasing the spacing between the waveguide and the cavity. Our two dimensional simulation results
show that the latter method resulted in cross talk reduction of more than 21 dB for both structures. The overall cross talk
was -90.50 dB for the cylindrical rods structure and -105.0 dB for the cubic rods structure. The optimized PhC structures
were fabricated on a silicon-on-insulator platform. The rods were buried in silicon oxide in order to maximize the
photonic band gap and provide index guiding in the vertical direction.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560F (2008) https://doi.org/10.1117/12.795321
In this work we present a method for creating an integrated optofluidic ring resonator (OFRR) laser system by
embedding it in a low index polymer, polydimethylsiloxane (PDMS). Packaging the OFRR inside PDMS enhances
portability, mechanical stability, and the ability to connect it to chip-based microfluidics. The OFRR retains high Q-factors
even in the polymer (> 106) and exhibits a low lasing threshold (<1 μJ/mm2). Additionally, the laser emission can
be efficiently and directionally coupled out through an optical fiber or fiber prism in touch with the ring resonator. At 2.2
μJ/mm2 pump intensity, the laser output from the fiber is 80 nW, corresponding to 50% power extraction efficiency. Our
work will lead to novel design in lab-on-a-chip devices and micro total analysis systems for biological and chemical
detection.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560G (2008) https://doi.org/10.1117/12.801264
Single-beam phase conjugation (self-phase conjugation, or SPC) was observed in the ferroelectric crystal
LiNbO3:Fe using CW HeNe laser (wavelength 632 nm power 10-36 mW). Effective "out/in" reflection
coefficient of phase conjugation (defined as the ratio the output phase-conjugated beam to the input laser
beam measured before optical elements) was about 30%. For some crystals efficient phase conjugation was
followed by the simultaneous generation of Fabry-Perot modes. Phase locking of two HeNe lasers and
imaging of the amplitude objects with the help of self-phase conjugation was demonstrated. Appearances of
additional beams (in transmission and reflection) have some analogy with the predicted behavior of the
"negative-index materials".
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Development in Component and Integrative Photonic Devices II
Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560H (2008) https://doi.org/10.1117/12.796874
Fiber SERS (surface enhanced Raman scattering) sensors have attracted significant interest in molecule sensing. In this
paper, we briefly review our previous work on various configurations for fiber SERS probes, including side-polished
fibers and various photonic crystal fibers (PCFs). In addition, we will report our recent experiments on a double
substrate "sandwich" structure for fiber SERS probe. The approach is to coat one SERS substrate on the tip of a
multimode fiber and mix the second substrate in solution with the target analyte molecules. Upon dipping the coated
fiber probe into the solution, randomly formed structures of the two substrates will sandwich the analyte molecules in
between. Our results show that the "sandwich" configuration exhibits significantly higher sensitivity than direct SERS detection.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560I (2008) https://doi.org/10.1117/12.795015
A novel generation of sensors of strain, temperature, absolute and relative molecular
concentration is reported. Such devices, based on 1-D photonic structures, rely on ultrastable laser sources,
referenced to a fiber-based optical frequency comb synthesizer (OFCS). In particular, recent advances in the
realization of two complementary laser sensors are presented. One is a spectroscopic facility which exploits
frequency mixing in a periodically-poled LiNbO3 crystal to generate highly coherent (a few hundred kHz
linewidth) infrared radiation tunable in the 2.9-3.5 micron wavelength range. Such radiation can be coupled
to high-finesse enhancement cavities to detect trace amounts of gases, including rare isotopes in natural
abundance. The other system, making use of fiber Bragg grating components, provides strain and
temperature sensing with extremely high sensitivities (about 100 fε, i.e. 10-13 ΔL/L). Due to the remoteness
guaranteed by the fiber coupling, these two systems can both be used in difficult environments and inserted
in a multi-parametric network for real-time and continuous monitoring of large areas. Prospects for
application in volcanic areas are also discussed.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560J (2008) https://doi.org/10.1117/12.794925
The application of photonic crystals in biosensor applications has lead to the development of highly sensitive and
selective sensor elements. The research efforts undertaken by this group have led to the development of a photonic
crystal transducer that acts as a waveguide, nanofluidic flow channel, and resonant defect cavity. This sensor architecture shows promise for greatly enhancing the emission of naturally fluorescent or fluorescently-labeled biomolecules. Due to its transparency in the visible regime, GaN is a viable candidate for this photonic crystal biosensor application. This paper provides an overview of the sensor architecture as well as a discussion of one particular bottom-up approach to its fabrication. Molecular Beam Epitaxy (MBE) growth of heavily Mg doped GaN can result in inversion of the surface polarity from Ga-polar to N-polar GaN. This bottom-up approach includes patterning and etching of the Mg inversion layer, followed by
re-growth of the opposite polarity to produce periodically poled GaN. Subsequent wet etching of N-polar regions then produces a GaN based photonic crystal structure. This process shows promise for achieving high aspect ratio, highly anisotropic nanostructures.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560K (2008) https://doi.org/10.1117/12.795138
We report for the first time, a single mode, tunable, double-clad ytterbium-fiber (YDF) laser emitting in a
wavelength range between 976 and 985 nm that operates using the re-imaging effect that occurs in multimode
interference (MMI) devices. The system consists of an YDF with bare fiber cleaved ends. The forward end of this fiber is
fusion spliced to a piece of 3 m of Samarium-doped- single-mode fiber with absorption measured at 980 nm of 0.3 dB/m,
and at 1030 nm of 6 dB/m. The other end of the Sm+3 doped single-mode fiber is spliced to a 16.2 mm long multimode
fiber (MMF) in order to induce the MMI self-imaging effect. From simulations, we found that, at this particular length,
for the MMF, the light exiting will exhibit a maximum transmission for the 980 nm wavelength, while keeping a
minimum for the 1030 nm wavelength. Near to the MMF facet, at a distance between 0 and 100 µm, we place a dichroic
mirror which also helps in the selection of the wavelength emission. We calculated that 10 dB gain generated at 980 nm
is enough to build up a laser since the total round-trip cavity losses are estimated to be 8.8 dB, whereas for the unwanted
1030nm get more than 60dB insertion loss in this setup. At the end, there is more than 1 dB for the effective gain at the
preferred wavelength emission range which is enough to promote lasing at around 980 nm.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560L (2008) https://doi.org/10.1117/12.795141
The paper presents theoretical and experimental investigations of the structure of the spatial distributions of strain
amplitudes for an oscillating surface using an optical interferometer. A conventional Michelson interferometer and
an interferometer containing an acousto-optic cell have been studied. It has been shown that the maximum possible sensitivity of the device is 0.001 Å, with the minimum strain amplitude reaching 0.001 Å. Practical advantages of the interferometer with an acousto-optical cell have been realized.
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Novel Materials and Devices: Theoretical and Experimental Approaches I
Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560M (2008) https://doi.org/10.1117/12.793541
We derive mathematical criteria for a pair of guided modes which have the same parity, mutually parallel wave vectors
along the guiding direction of the waveguide, but opposite directions of optical power flow in a negative-index slab
waveguide using a graphical method. It is also proven that the so-called light trap mode corresponds to the degenerate
mode of this pair. We also propose a waveguide structure in which guided light waves can be trapped via tunneling
through thin metamaterial clad layers. This trap is temporary since the trapped light tunnels out completely after a short time.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560N (2008) https://doi.org/10.1117/12.796466
In this paper, a novel all-fiber band pass filter based on a concatenated structure of multimode fiber, single-mode core
mode blocker and a single-mode long period fiber grating was reported. It can simultaneously serves as a band pass
filter and multimode-single-mode converter for interconnection between multimode fiber and single mode fiber
network. The theoretical analysis, designing, fabrication and experiments result were presented.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560P (2008) https://doi.org/10.1117/12.792084
Single-mode optical fibers for the mid-IR (λ=3-30μm) are needed for many applications such as IR fiber lasers
and spatial filtering for nulling interferometry. In the past, we have already reported the design and fabrication of stepindex
single mode fibers for the mid-IR. Index guiding photonic crystal fibers (IG-PCF) offer many advantages over
step-index fibers, such as a wide spectral range, large mode area and low bending losses. So far, only limited success has
been achieved in the development of such fibers, due to the lack of suitable materials that are transparent in this spectral
range. We report here the design, fabrication and optical characterization of single-mode IG-PCFs for the mid-IR.
Triangular and octagonal IG-PCFs were fabricated from silver halide polycrystalline materials which transmit well in the
spectral range 2-20μm. The photonic crystal fibers were characterized by near-field and far-field measurements and they
demonstrated a single-mode behavior with relatively low losses and a large mode area, in agreement with our simulations. As predicted from the simulations, the octagonal arrangement of the rods in the fiber resulted in a single mode fiber with lower losses, a better mode shape and a higher rejection of high order modes, in comparison to the
triangular structure.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560Q (2008) https://doi.org/10.1117/12.792007
We continue a study of the equivalence particle principle applied to an optical spatial soliton which is a "narrow filament" that maintains its existence in a waveguide. Using this principle, expressions for acceleration, spatial frequency, spatial period and other variables for a spatial soliton can be derived from the solution of basic Nonlinear Schrödinger Equation. These results agree well with numerical simulations of the Modified Nonlinear Schrödinger Equation. If the expression of the acceleration is bounded in some cases this means the spatial soliton propagates with a swing effect. We go one step further in this theoretical study to investigate the effects of the swing effect with power law included in the Modified Nonlinear Schrödinger Equation.
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Novel Materials and Devices: Theoretical and Experimental Approaches II
Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560R (2008) https://doi.org/10.1117/12.793214
A novel architecture of an optical filter for pulse compression in dense wavelength-division multiplexing
(DWDM) systems is presented. We propose a comb filter for dispersion compensation within a transmission
channel. A pair of chirped gratings with slanted grating lines is used. The effect of filtering is not based on
resonances as used in Bragg gratings, but it is achieved by interferences of parts of the optical wave. Furthermore,
the filter concept enables an amplification to compensate transmission losses. The filter parameters
are adjusted by different phase shiftings of the grating lines. Their geometrical dimensions are equal for all
grating lines. It will be shown, how different grating lengths and phase shiftings between the grating lines
contribute to the transmission characteristic of the filter. We will give design rules for the chirp to develop
appropriate filter functions for positive or negative dispersion values up to 1500 ps/nm while the linearity of
the group delay is restricted to 6.5%. The performance of the structure will be presented by a filter designed
for a DWDM-system with a channel distance of 0.4 nm.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560S (2008) https://doi.org/10.1117/12.794039
An ultrafast light-activated magneto-optical modulator is demonstrated in this paper. This modulator is capable of 1 ns
modulation speed and has a 1 mm clear aperture. The design of the modulator incorporates a photoconductive switch and
enables a synchronized and jitter-free operation, which eliminates the need of any electrical or optical delay lines. These
features make the current design very attractive in typical free-space pulse laser applications. To the authors' knowledge,
this is so far the fastest MO modulator with such aperture size that has been reported.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560T (2008) https://doi.org/10.1117/12.794859
Dual Band Wavelength Demultiplexer (DBWD) is designed to separate two telecommunication wavelengths, 1.31μm
and 1.55 μm utilizing photonic crystals (PhC) in Silicon on Insulator (SOI). The waveguides formed in such PhC
structures confine light horizontally by a photonic bandgap and vertically by total internal reflection. Plane Wave
Expansion (PWE) method and Finite Difference Time Domain method are used to design and analyze the DBWD in Y
type PhC. Numerical analysis indicates that the separation of two wavelengths with enhanced extinction ratio,
transmittance and quality factor can be achieved, which confirms the superior performance of the proposed design of
DBWD
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560U (2008) https://doi.org/10.1117/12.806614
We present a study of polarization rotation enhancement in birefringent magneto-optic photonic crystal waveguides
and provide theoretical and experimental support for a novel type of photonic bandgap. The coupling
between counter-propagating elliptically birefringent local normal modes of different order results in the formation
of partially overlapping bandgaps and selective suppression of Bloch state propagation near the band edges.
We use a bilayer unit cell stack model with an alternating system of birefringent states in adjacent layers. A
magnetically tunable and large polarization rotation of the allowed Bloch modes near the band edges is computed
theoretically and observed experimentally.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560V (2008) https://doi.org/10.1117/12.793942
In this paper, the two different mechanisms of supercontinuum generation in single crystal sapphire fibers according to
fiber lengths longer and shorter than dispersion length are theoretically and experimentally investigated. When the fiber
length is shorter than the dispersion length, self-phase modulation is the dominant factor for supercontinuum broadening.
A broad spectrum ranging from near-IR (1.2 μm) to the lower end of mid-IR (2.8 μm) is obtained. But, when the fiber
length is longer than dispersion length, soliton-related dynamics with self-phase modulation is the dominant factor for
supercontinuum. We further demonstrate that supercontinuum in a sapphire fiber can extend beyond the range of silica
fibers by showing the spectrum from 2 μm to 3.2 μm. Also, we successfully apply the supercontinuum source generated
from a sapphire fiber to IR spectroscopy. The spectra of pseudo-TNT chemical measured using our own supercontinuum
source is in good agreement with those obtained by FTIR. Supercontinuum generation using a sapphire fiber, which has
high damage threshold and broad transmission ranges can be used in many applications such as IR spectroscopy,
broadband LADAR, remote sensing, and multi-spectrum free space communications.
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R. M. Wynne, K. Creedon, B. Barabadi, S. Vedururu, J. Merritt, A. Ortega
Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560W (2008) https://doi.org/10.1117/12.794226
A sensing configuration based on commercially available hollow-core photonic bandgap (PBG) fiber for the
simultaneous optical detection of multiple gas samples is presented. Spectroscopic sensors based on microstructured
fiber technology have been of recent interest. However, most designs have limited sensor response times due to long gas
diffusion filling times for fiber lengths >1 m. Sensor response times that are shorter in duration unlike diffusion-limited
filling times are reported. A length of PBG fiber with a 12.5 micron core diameter, an optical spectrum analyzer and a
broadband light source were employed to operate in the transmission region where the absorption lines for sample gases,
including acetylene and carbon dioxide, correspond to the near-IR region. A gas-filling time of 1 minute 30 seconds for
acetylene to completely fill a ~2 meter length of PBG fiber at a pressure < 15 Psi was demonstrated. Reduced filling
times that approach the sub-minute regime are possible, leading to shorter sensor response times. The sensitivity of the
proposed system is also reported. Using the techniques presented, the detection of concentrations < 100 ppm for
acetylene gas at pressures < 15 Psi is possible. The relatively
low-loss PBG guidance mechanism (< 0.1 dB/m) confines
light to the gas-filled region promoting long optical-field-interaction lengths (> 1 m) with small sample volumes (~μL)
resulting in a compact, bend-insensitive rugged device with gas detecting sensitivities that have the potential to be higher
than capillary based detectors.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560X (2008) https://doi.org/10.1117/12.794979
Using 2D finite element modeling with the ability to solve the current continuity equations, carrier energy transport
equation, Schrödinger and Poisson equations self-consistently, as well as the scalar wave equation for waveguiding
devices, we have investigated the possible improvements of the device efficiencies by introducing transparent p-type
contacts and multiple quantum shells (MQSs) in GaN / In0.14Ga0.86N / GaN / p-AlGaN / p-GaN core/multishell nanowires
(CMS NWs). The addition of a transparent p-type current spreading contact was found to promote more uniform current
injection into the CMS NWs, thus increasing the current injection efficiency. Despite the inclusion of a transparent ptype
contact, the current density remained non-uniform and weighted towards the n-contact side of the NW. This
asymmetry in the current density was found to be more important for higher injection current whereas it becomes much
more uniform with decreasing injection current. Light generation with the transparent contact was found to become more
uniformly distributed along the CMS NW, leading to more even light generation within the device in comparison to
NWs without transparent p-type contacts. The replacement of single quantum shells (SQS) by MQSs in the active
region of the nitride CMS NW-as has been used for conventional InGaN high brightness LEDs (HB-LEDs)-was found
to be advantageous up to three quantum shells, increasing light generation from 80.47 to 94.04 W/m under a 4V bias.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560Y (2008) https://doi.org/10.1117/12.796343
Laser-induced domain inversion is a promising technique for domain engineering in LiNbO3 and LiTaO3. The
ultraviolet-infrared laser induced domain inversions in MgO-doped congruent LiNbO3 and near stoichiometric LiTaO3
crystals are investigated for the first time here. Within the wavelength range from 351 to 799 nm, the different reductions
of nucleation field induced by the focused continuous laser irradiation are systematically investigated in the MgO-doped
congruent LiNbO3 crystals. The investigation of ultrashort-pulse laser-induced domain inversion in MgO-doped
congruent LiNbO3 is performed with 800 nm wavelength irradiation. The focused continuous ultraviolet laser-induced
ferroelectric domain inversion in the near stoichiometric LiTaO3 is also investigated. The different physical explanations,
based on space charge field and defect formation, are presented for the laser-induced domain inversion, and the solid
experimental proofs are also presented. The results provide the solid experimental proofs and feasible schemes for the
further investigation of laser-induced domain engineering in
MgO-doped LiNbO3 and near stoichiometric LiTaO3
crystals. The important characteristics of domain inversion, including domain wall and internal field, in LiNbO3 crystals
are also investigated by the digital holographic interferometry with an improved reconstruction method, and some
creative experimental results and conclusions are achieved.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560Z (2008) https://doi.org/10.1117/12.797994
Polarization data of a SM gyroscope coil may correlate to drift that provides a method to statically predict a
performance range of a coil during manufacturing or at a minimum before integration into a FOG assembly. The
Crossover Free (CF) coils described here are thermally symmetric and lack fiber crossovers. This design allows
possible expansion of depolarized FOGs beyond the research environment. To that end a series of double sided
CF gyroscope coils were manufactured and analyzed using a 4 channel fiber coupled polarimeter. In addition the
coils were tested on a single axis rate table in a FOG testbed. A polarimeter was used to measure the output
polarization state of the stand-alone coils and when integrated into an experimental FOG testbed. In addition
Shupe data of the CF coils was taken to determine the thermal sensitivity of the coils. Coil geometry and
construction, polarimetric and traditional drift data, and Shupe performance will be presented.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705611 (2008) https://doi.org/10.1117/12.795606
Due to the high-index contrast between the silicon core and silica cladding, the silicon waveguide allows strong optical
confinement and large effective nonlinearity, which facilitates low cost chip scale demonstration of all-optical nonlinear
functional devices at relatively low pump powers. One of the challenges in ultrafast science is the full characterization of
optical pulses in real time. The time-wavelength mapping is proven to be a powerful technique for real time
characterization of fast analog signals. Here we demonstrated a technique based on the cross-phase modulation (XPM)
between the short pulse and the chirped supercontinuum (SC) pulse in the silicon chip to map fast varying optical signals
into spectral domain. In the experiment, when 30 nm linearly chirped supercontinuum pulses generated in a 5 km
dispersion-shifted fiber at the normal regime and 2.4 ps pulse are launched into a 1.7 cm silicon chip with 5 μm2 modal
area, a time-wavelength mapped pattern of the short pulses is observed on the optical spectrum analyzer. From the
measured spectral mapping the actual 2.4ps temporal pulse profile is reconstructed in a computer. This phenomenon can
be extended to full characterization of amplitude and phase information of short pulses. Due to time wavelength
mapping this approach can also be used in real time amplitude and phase measurement of ultrafast optical signals with
arbitrary temporal width. The high nonlinearity and negligible distortions due to walk off make silicon an ideal candidate
for XPM based measurements.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705613 (2008) https://doi.org/10.1117/12.794916
This work presents a research in which a Twin Core Fiber (TCF) has been employed for designing a Mach- Zehnder
interferometer and its behavior under the effect of thermal gradients has been regarded. From the coupled modes theory
can be deduced that under the phase-matched condition-that is similar propagation constants in both cores of a TCF,
the energy transported in the cores is the same, which is fundamental for developing this interferometer. This research
required to design a thermal cavity and an automation circuit for applying thermal cycles to a segment of the TCF. The
temperature was recorded by means of a thermocouple placed inside the thermal cavity and its signal was introduced into
the computer where an instrumentation software (Lab View) designed for monitoring and controlling variables used this
signal for controlling the on-off states of a power resistor and a refrigeration system for raising and lowering the
temperature, respectively. It was observed that the optical power variations in a point of the interference pattern
presented a weak dependence with the thermal cycles.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705614 (2008) https://doi.org/10.1117/12.793810
A key stage in production of the integrated optics devices is forming of microtopography on crystalline films. The
current methods generally comprise two separate steps: producing of thin film and creation a topographical pattern on it.
But the inherently large chemical stability of crystalline LiNbO3 has effectively precluded the use of standard
photolithographic patterning techniques. We present new approach based on the modified sol-gel technology using the
photosensitive gel. In this case, the photolithography is used on the stage of dried gel whereupon the direct
crystallization of patterned precursor film allows to create integrated optical element without subsequent etching of
crystalline film. Presented method of patterned thin film preparation involves synthesis of photo-reactive complex of
metal, which undergoes change under the UV light. This technology has allowed to obtain first samples of different
types of waveguide devices.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705616 (2008) https://doi.org/10.1117/12.798354
Piezoelectric resonance contributions to the electrooptic coefficients in ferroelectric PZN-8PT single crystals were
studied by a dynamic electrooptic measurement carried out using a continuous frequency scan over the range of
frequency covering the sample's fundamental resonances. At certain frequencies relevant to piezoelectric resonance of a
given mode, it is found that the E-field modulated optical transmission are greatly enhanced (> 2 orders of magnitude).
Such enhancement is mode selective and scales with strain or the rate of change of dielectric permittivity. Instead of
having linear dependence on the electric field, the piezoelectric resonance enhanced optical transmitted signal in this
crystal shows a near linear response to the power of the modulating electric field.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705618 (2008) https://doi.org/10.1117/12.793962
The double threshold effect of ultraviolet laser-induced preferential domain nucleation in near stoichiometric
LiTaO3 is observed. The continuous ultraviolet laser beam (351 nm) is focused on the -z surface of the
wafer, and the homogeneous electric field is applied simultaneously antiparallel to the direction of
spontaneous polarization along the z axis. The double threshold effect includes both the primary and the
secondary thresholds. The primary threshold is the minimum intensity to achieve the instantaneous
preferential domain nucleation within the focus by the combined action of irradiation and electric fields.
Below the dark nucleation field, the instantaneous preferential domain nucleation is achieved within the
illuminated area when the intensity exceeds the primary threshold. The experiments prove that the domain
inversion can be locally controlled by the laser irradiation. The secondary threshold is the minimum intensity
to achieve the memory effect without any irradiation within the original focus. The memory effect of
preferential nucleation is observed when the intensity is below the primary threshold and above the secondary
threshold. The preferential domain nucleation of memory effect is investigated. The different physical
explanations are presented for the instantaneous effect and memory effect. The space charge field created by
the photoionization carriers is thought to be responsible for the instantaneous effect. The explanation based on
the formation and transformation of extrinsic defect is presented for the memory effect.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705619 (2008) https://doi.org/10.1117/12.794036
In this paper, we experimentally verify that previously proposed idea of unequally spaced optical phased array can
greatly reduce grating-lobes. As the verification purpose of our previous numerical design, a laser beam is passed
through unequally-spaced slits, whose spacings are the same as the previous design. Interference patterns formed after
both 4- and 8-channel slits clearly show that the grating-lobes can be greatly minimized. To realize the beam steering
possible, optical waveguides array, which has unequally spaced design at the output ends is fabricated. The phase of
each beam can be varied using fibers array wound around PZT tubes before each beam is coupled into the waveguides
array. Interference patterns formed after the outputs of both 4- and 8-channel waveguides array show that the gratinglobes
can be greatly reduced using unequally spaced optical phased array technique.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561A (2008) https://doi.org/10.1117/12.794040
Because the efficiency of THz generation in air plasma is quite low, the residual power of input beam after THz
radiation is generated in air plasma remains almost the same. A new method, multiple air plasmas, is proposed. The
residual power can be used to induce other air plasmas and generate THz radiation again. The multiple air plasmas
method provides a potential way for the development of the intense THz source. The preliminary experimental
results confirm the theoretical prediction. The multiple air plasmas generated THz can be very useful for remote
THz generation and standoff detection.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561B (2008) https://doi.org/10.1117/12.794141
Crystal growth and spectroscopic characterization of Ni-doped MgGa2O4 belonging to inverse-spinel structure crystal
family are described. Single crystals of this material were grown by floating zone method for the first time. Oxygen gas
flow was essential to minimize evaporation of Ga2O3 during the floating zone crystal growth process. Bubble and
inclusion-free crystals were obtained for the growth rate less than 5 mm/hour. Ni:MgGa2O4 single crystal was
characterized by broadband fluorescence in 1100-1600 nm wavelength range and 1.6 msec room-temperature lifetime. It
could be attributed to the transition of 3T2(3F)→3A(2F) transition of the octahedrally coordinated Ni2+. The internal
quantum efficiency of the near-infrared fluorescence was about 82 % for 1 mol% Ni-doped MgGa2O4 single crystal at
room temperature. The new material is to be very promising for tunable laser applications covering the important optical
communication, eye safe, 1100-1600 nm wavelength.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561C (2008) https://doi.org/10.1117/12.794433
In this paper, superprism phenomena based on phase velocity has been studied. PCs composed of air holes of
different shapes in a triangular lattice with constant filling fraction have been taken under study. The
observation of superprism behavior has been made using angle sensitive and wavelength sensitive propagation
of light. It has been found that the PC with hexagonal rod geometry yields the best behavior of the superprism in
the case of angle sensitive propagation. For wavelength sensitive propagation PCs with hexagonal and circular
air holes provide almost the same angular separation. Therefore we can conclude that the PC with the air-rod geometry of hexagon is the most suitable candidate for optical devices based on superprism phenomena.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561D (2008) https://doi.org/10.1117/12.794661
High diffraction efficiency of each grating is desired to reduce light intensity loss when gratings are integrated to realize
miniaturization for 3-D optical instruments in LiNbO3 crystals. Based on jointly solving the two-center material
equations, oscillating behavior of diffraction efficiency during recording and erasing process is investigated theoretically
to realize maximized diffraction efficiency for integrated volume grating instruments in weak oxidized doubly-doped
LiNbO3:Fe:Mn crystals. Two nonvolatile gratings are integrated and nonvolatile diffraction efficiency for each grating
exceeds 60%. These methods depend on the dopant elements and its concentrations, annealing (or oxidation-reduction)
in doubly-doped LiNbO3 crystals, and recording and sensitizing intensities and wavelengths. The experimental
investigation will be performed to verify the calculated results.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561E (2008) https://doi.org/10.1117/12.794908
The multimode interference (MMI) couplers, which operate at 1.55 microns in deep rib InGaAsP/ InP waveguide with
large lateral confinement and tunable power splitting ratios, are of high interest in integrated optics. The gold contacts
are applied on the top of waveguides where tuning is desired and the plasma effect will lead to negative refractive index
change. The three-dimensional (3D) finite difference beam propagation method (FD-BPM) is used to model the tunable
MMI couplers. The length of a 2×2 overlap-MMI is determined by FD-BPM, so the longitudinal position of tuning spots
is obtained. The position of gold contacts with two types, the edge-pads or center-pad, are also determined. In our design,
the length of MMI is 180 microns. If the width of pads is 50 micros and the refractive index is tuned from 0 to -0.027,
the power ratio is tuned from50:50 to maximums 88.5:11.4. For deep rib structure, the effective index (EI) method can
not be used to simplify the 3D waveguide to plane waveguide because its lower precision, and then the direct 3D FD-BPM
simulation is necessary for the design of 3D MMI couplers.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561F (2008) https://doi.org/10.1117/12.795014
SiO2-based diffractive/refractive hybrid microlenses were fabricated by using femtosecond laser-induced nonlinear
optical processes. Recently, hybrid devices have received much attention as important components for optical pickup
systems and integrated sensors. SiO2-based devices are particularly promising because of high transparency, physical and
chemical stabilities. For these devices, microfabrication upon nonplanar substrates such as convex lenses, which is
difficult for the semiconductor processes, is required. In this study, microFresnel lens patterns were directly written
inside positive-tone resists upon convex microlenses of 240 μm diameters by using femtosecond laser-induced nonlinear
absorption. The spot diameters are primarily determined at any position inside the resist by the region volume at which
the nonlinear absorption occurs. Therefore, the precise patterns could be formed even upon the nonplanar substrates.
After post-exposure-bake and development treatment, the patterns were transferred onto underlying lenses by CHF3
plasma. Here, the etching depth was 1 μm. Consequently, SiO2-based hybrid lenses with smooth surfaces were obtained. When He-Ne laser of 632.8 nm wavelength was coupled to this hybrid lens, the focal spot was 630 μm from the lens
surfaces. This focal length agreed with theoretical value of 618 μm. More functional optical devices would be realized
by improvement of fabrication processes.
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Wei Li, Guoying Feng, Qiuhui Zhang, Tianxiang Zhang, Hai Liao
Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561G (2008) https://doi.org/10.1117/12.795217
Using split-step algorithm based on the fast Fourier transform and a fourth-order Runge-Kutta(R-K) method, we studied
the second-harmonic generation(SHG) of high power laser with KDP crystal. The transverse walk-off effect, diffraction,
the second-order and the third-order nonlinear effects of KDP crystal have been taken into consideration. Special
attention has been paid to the influences of a kind of self-induced thermal effect. The phase mismatching quantity, the
intensity distribution of output beam and the frequency conversion efficiency varying with the crystal temperature
distribution have been analyzed. The calculated results indicate that self-induced thermal effects results in the
temperature distribution in KDP crystal and the phase mismatching, then the phase mismatching leads to the decreasion
of the conversion efficiency.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561I (2008) https://doi.org/10.1117/12.802216
An optical system built with two Optune interferometers cascaded according to Vernier principle has attractive tunable
band pass filtering properties for numerous applications. Several characteristics of Optune interferometer such as 0.2 dB
insertion loss flatness across at least 90 nm interval, no tuning holes across 240 nm tuning range, quasi-periodic free
spectral range and 1 dB insertion loss are key parameters to obtain a cascade with 0.1 nm band pass tunable across
minimum 90 nm. Several properties of Optune interferometers are analyzed to build a cascade tunable across minimum
90 nm: the relationships between the free spectral ranges, bandwidths and tuning conditions. It is presented also a
cascade prototype with two interferometers having 9.72 nm free spectral range and respectively 11.12 nm free spectral
range. The cascade band pass is 0.1 nm tunable with 1 pm accuracy to any arbitrary wavelength across 150 nm free
spectral range, without any tuning hole. It has 0.125 ms / 100 nm tuning speed, the insertion loss is less than 3 dB, 50 dB
contrast, 0.5 dB flatness and 0.2 dB polarization dependent loss. A controller based on digital signal processor monitors
the operation of the cascade to achieve optimum tuning performance.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561K (2008) https://doi.org/10.1117/12.795811
We design air cladding tellurite (TeO2), bismuth oxide (Bi2O3) based, and chalcogenide (As2S3) nanofibers, and calculate
the chromatic dispersions. For each material, wavelength dependent propagation constants of the nanofiber are obtained
from the exact solutions of the Maxwell's equations, and from the propagation constants the chromatic dispersion is
calculated. We tailor the dispersion to zero at the communication wavelength, 1.5 μm, by proper selection of the core
diameter of the nanofiber for all the above materials. We further explain the technique for flattening the zero dispersion
in telecommunication window, using glass instead of air, as the cladding of the nanofiber structure. Using the glass
cladding has the advantage of easy handling, specially, for the communication purposes. Further, the glass cladding
causes larger effective index difference between various modes of the nanofiber, thus reducing the mode coupling. We
present the numerical results of the dispersion flattening technique by assuming the borosilicate glass cladding to the
chalcogenide As2S3 glass core nanofiber. With the borosilicate cladding the dispersion characteristics of the nanofiber
change drastically and flattening of the zero dispersion is achieved at 1.408 μm wavelength, when the core diameter is
724 nm.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561N (2008) https://doi.org/10.1117/12.796422
The phase-shifting errors mainly result from the imprecise movement of phase-shifter and the vibration of system. These
geometric errors are classified into the positional inaccuracy and tilting of optics. And they can be represented as the
longitudinal and transversal displacements of interferograms on the hologram plane. In this paper, we propose adaptive
phase-shifting digital holography compensating these two displacements and this proposed method is based on genetic
algorithm for finding optimized variables corresponding to real system. By computer simulations, the deteriorations in
reconstruction image are modeled and the chromosomes are constituted. We find the fittest solution compensating the
longitudinal and transversal displacements experimentally and present the reconstruction images by encoding the
resultant holograms on a spatial light modulator.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561O (2008) https://doi.org/10.1117/12.796551
We have observed generation of the electron beam by the pyroelectric crystal placed in the vacuum
chamber. Different pyroelctric materials, Fe-doped LiNbO3 and L-alanine doped TGS crystals, were tested.
Crystals of L-alanine doped TGS (LATGS) were grown by evaporation of the solution with 10% initial
concentration of L-alanine under T=45°C (somewhat below phase transition temperature TC = 49.9°C). In
this case crystallization proceeds immediately in the polar phase
Heating/cooling cycles of the crystals in the vacuum (P~ 1-5 mTorr) produce uncompensated surface
charges and strong electric field (~ 100kV/cm) on the polar crystal faces. These fringing fields ionize
ambient gas and accelerate electrons to high energies (~100 KeV). For photosensitive LiNbO3 crystal
electrical charging and generation of electrons may be done by laser illumination, via photogalvanic effect.
These generated electrons can be detected by the fluorescent ZnS screen or by the X-rays produced by
placing copper plate in the electron beam. Model that explains and figures that depict the self-focusing of
the electron beam is presented.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561P (2008) https://doi.org/10.1117/12.796695
A 3D sensing method to describe an entire shape from many segmented measurements performed by projected fringe
profilomety is presented. Unlike conventional algorithms, image registration is not required in this setup. Among all
other integration schemes, this method is superior since it offers many major advantages, including: (1) very low
computation cost for the data fusion, (2) reduced computational time, and (3) very high integration accuracy.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561Q (2008) https://doi.org/10.1117/12.796697
The speckle that is formed in coherent illumination confuses efforts to record an object's fine details. The confusion is
particularly severe in optical metrology and microscopy. In this paper, a scheme using the empirical mode
decomposition (EMD) to remove speckles is proposed. This makes it possible to accurately evaluate phases from a
fringe pattern illuminated by a coherent light source.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561R (2008) https://doi.org/10.1117/12.796700
We propose a projection scheme using a diffraction element for finding the absolute shape of an object with large depth
discontinuities. Its application built into an endoscope to retrieve an object inside a body cavity is presented as well.
Among all existing fringe projection schemes, this proposed method is notable for its compact design. Only one phase
measurement is required. To inspect a dynamic object is desirable.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561S (2008) https://doi.org/10.1117/12.796775
Recently magneto-optic spatial light modulators (MOSLMs) using magnetic garnet materials have advantages of high
switching speed. However, these materials are difficult to be used in short wavelength range, so that it appears huge light
absorption by magneto optic effect of transmittance mode (Faraday effect). This problem can be solved by using the
materials of metal magnetic films for magneto optic effect of reflection mode (Kerr effect). We suggest the new method,
which is the switching of pixels by heating the pixels with semiconductor laser until Curie temperature and changing the
direction of the driving current at the same time, for developing high speed MOSLM in broadband using amorphous
TbFe films. TbFe films were fabricated by RF sputtering using the Tb21Fe79target, and we have confirmed Kerr rotation
(over 0.4 degree from 400nm to 800 in wavelength), the curie temperature (130 degree Celsius), and the switching of
pixels of 16μm × 16µm by heating the pixels with semiconductor laser and controlling magnetization from external bias
magnetic field (15Oe) and driving current (20mA) of coil at 403, 532 and 633nm wavelength.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561T (2008) https://doi.org/10.1117/12.796791
The subject of this project is the design; analysis, fabrication and characterisation of first order Bragg
Grating optical filters in Silicon-on-Insulator (SOI) planar waveguides. It is envisaged that this work will
result in the possibility of Bragg Grating filters for use in Silicon Photonics. It is the purpose of the work to
create as far as is possible flat surface waveguides so as to facilitate Thermo-Optic tuning and also the
incorporation into rib-waveguide Silicon Photonics.
The spectral response of the shallow Bragg Gratings was modelled using Coupled Mode Theory (CMT) by way of RSoft Gratingmod TM. Also the effect of having a Bragg Grating with alternate layers of refractive index of 1.5 and 3.5 was simulated in order to verify that Silica and Silicon layered Bragg Gratings could be viable. A series of Bragg Gratings were patterned on 1.5 micron SOI at Philips in Eindhoven, Holland to investigate the variation of grating parameters with a) the period of the gratings b) the mark to space ratio of the gratings and c) the length of the region converted to Bragg Gratings (i.e. the number of grating period repetitions).
One set of gratings were thermally oxidised at Philips in Eindhoven and another set were ion implanted with Oxygen ions at the Ion Beam Facility, University of Surrey, England. The gratings were tested and found to give transmission minima at approximately 1540 nanometres and both methods of creating flat surfaces were found to give similar minima. Atomic Force Microscopy was applied to the grating area of the as-implanted samples in the Advanced Technology Institute, University of Surrey, which were found to have surface undulations in the order of 60 nanometres.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561U (2008) https://doi.org/10.1117/12.796799
In angle multiplexing, the angle between the reference light and the object light is slightly changed in different
recordings. In reconstruction, only the reference beam with an accurate angular position can retrieve the corresponding
object beam due to the characteristics of Bragg condition. Accordingly, a suitable angular separation of the reference
beam should be decided for angle multiplexing. A larger angular separation will decrease the storage density, and a
smaller angular separation will increase the cross-talk noise in small bi-angles. In general speaking, only one condition
of full angle of lights is involved to calculate the angular separation with coupled-mode theory or with experiment. Thus
the angular separation is fixed in the whole procedure of angle multiplexing. As a result, the angular separations of most
multiplexed holograms are either larger or smaller. Only one hologram is multiplexed in the critical angular condition. In
this paper, angle multiplexing with different angular separations were performed to quantitatively demonstrate the effect.
The possible method to deal with the issue was also proposed.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561V (2008) https://doi.org/10.1117/12.795005
The production of CuInGaSe2 (CIGS) solar cell is based on vacuum processes, which requires a high manufacturing
temperature and high cost. Our result show a simple method has been developed to prepare the silica substrates of CIGS
solar cell. It's synthesized by sol-gel process from tetraethylorthosilicate (TEOS), methanol (CH3OH) and pure water (both ion-exchange and distillation) in the presence of ammonia as catalyst. The preparation procedure was elaborated as
the flexible sequence to control chemical composition and properties of the particles in sol-gel-derived silica substrate.
The morphology, particle size, and size distribution of CIGS substrate were characterized with dynamic light scattering
(DLS) and atomic force microscopy (AFM). The results of AFM morphology and statistic evidence we find an easy way,
non-vacuum and low temperature processes, to successfully prepare the CIGS solar cell substrates with surface roughness below 3 nm. It is powerful the advance study in low cost solar cell.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561W (2008) https://doi.org/10.1117/12.794459
Nonlinear optics in silicon has drawn substantial attention in the recent years. In this research, laser mode-locking and
dual wavelength lasing are achieved in a fiber-ring-cavity using an Erbium-doped fiber amplifier (EDFA) as a gain
medium and a 1.7cm long silicon-on-insular waveguide as pulse compressor, a mode-locker and a Raman gain media.
We show that the transient behavior of two photon absorption (TPA) and TPA induced free carrier absorption can be
used for pulse compression and laser modelocking in the silicon waveguide inside the laser cavity. The proposed
technique takes advantage of spontaneous generation of free carriers and the slow recombination time, >17ns, to
attenuate the trailing edge of the time varying signals passing through the waveguide. When a 5μm2 model area silicon
waveguide is placed inside a fiber ring cavity consisting of an EDFA as a gain media and ~50ps modelocked laser pulses
are generated at 1540nm. We also observe that the generated short pulses also induce stimulated Raman scattering at
1675nm in the same silicon waveguide. We show that engineering the laser cavity facilitates laser modelocking and dual
wavelength laser oscillation at 1540nm and 1675nm. Experimentally we obtain <100ps modelocked pulses at both wavelengths. The average pump threshold power of the Raman laser is measured to be 3.75mW and the Stokes average output power is measured to be 3 μW.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561X (2008) https://doi.org/10.1117/12.796691
We present a discussion on how an area-encoded fringe pattern is applied to describe the 3D shape of complex objects
that have spatially isolated surfaces or large depth continuities. Compared with conventional fringe projection
techniques, the proposed scheme is relatively reliable and robust to identify the fringe order. Only one phase
measurement is required. This makes it possible to analyze dynamic objects.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70561Y (2008) https://doi.org/10.1117/12.793404
Temperature and strain sensing of critical aircraft engine components is a critical health and prognostics tool for future
engine programs. Real-time feedback of key temperature and strain measurements can be used to provide better
estimates to ground crews of engine component life, thus minimizing engine downtime and maximizing the effectiveness
of planned inspections. One method for monitoring distributed stress and temperature throughout an engine is through
the use of Fiber Bragg Grating (FBG) sensors. With just a single sensor line, both temperature and strain can be
monitored simultaneously and in a distributed fashion. Unfortunately, FBG sensors bonded to a host structure are
susceptible to both thermal strains and mechanically-loaded strains simultaneously, and without intelligent sensor design,
the two signals are indistinguishable from each other. In the present work, a sensing array design is proposed and
demonstrated to provide a means for separating thermal and mechanically-loaded strain signals by using two FBG
sensors in close proximity to each other. Experimental results are provided using a structural beam element to
demonstrate the feasibility of the proposed approach for decoupling the temperature and strain effect from fiber Bragg
grating sensors.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705620 (2008) https://doi.org/10.1117/12.795021
A design of polarization beam splitter based on negative refraction in photonic crystal is proposed. The proposed structure is formed by a hexagonal lattice of embedded air holes in silicon materials and is based on 2-D photonic band structure and equi-frequency contour calculations where negative refraction is considered to be function of incident angle and thickness of slab. The designed structure exhibits oppositely signed (negative and positive) refraction for TE and TM polarization at telecom wavelength windows. The wavelength response of the designed PBS is obtained for both polarizations.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705622 (2008) https://doi.org/10.1117/12.801497
By using two optical fibers and a capillary it is possible to measure the refractive index of liquids. Light
leaving a fiber is sent transversally to a capillary that behaves as a cylindrical lens when liquids are
inserted in it. Focused light is collected by a second fiber and sent to a detector.
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Proceedings Volume Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705623 (2008) https://doi.org/10.1117/12.804262
The SIM-Planetquest (Space Interferometry Mission), currently under development at the Jet Propulsion Laboratory,
consists of two 6-meter baseline interferometers on a flexible truss. SIM's science goals require 1μas accuracy in its
astrometric measurements[1]. To achieve this level of accuracy for detecting planets SIM built the Spectrum Calibration
Development Unit (SCDU) testbed. The testbed requires a white light point source with broadband spectrum. Before
each long test the spectrum on the camera must be calibrated. To achieve this task a laser light visible to camera was
coupled to the white light source. The light system needed pointing stability of better than 4 micro-radians and a
minimum optical power level at the fringe tracking camera. Due to stability requirement of the experiment, the setup,
including the point source is in a vacuum chamber. To get a broadband spectrum point source inside the vacuum
chamber white light from a multimode fiber was combined with laser light in free space to a photonics crystal fiber
(PCF). The output is a single mode, broadband, and Gaussian beam. This paper explains the details of such a design and
shows some of the results.
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