This PDF file contains the front matter associated with SPIE Proceedings Volume 11604, including the Title Page, Copyright information, and Table of Contents.

The performance of space-to-ground laser communication system is mainly affected by free space and atmospheric environment. First, the effects of atmospheric environment (fog, cloud, turbulence), beam spread, ATP pointing errors, and sky background radiation on the communication system are analyzed. And the closed-form expressions of performance parameters of the intensity modulation/direct detection communication system such as link margin, achievable data rate, and bit error rate obtained by using the received signal optical power and the received sky background optical power. The influence of atmospheric environment on the performance of 1550nm wavelength space-to-ground laser communication system is simulated and calculated. The results show that turbulence has the greatest influence on the performance of air-to-ground laser communication, followed by fog; when 16-PPM modulation scheme is adopted, the communication distance and performance are greatly improved; when the atmospheric environment is weak turbulence, cirrus cloud and visibility is greater than 5 km, the maximum bit error rate is 10^-105 orders of magnitude on the communication link with angle of elevation of 30 degree and altitude of 12 km.

There is a broad application of laser communication. This technology makes a great contribution to information exchanging between a station on ground and a satellite in space or between two satellites in space. Transceiver of space laser communication usually shares one optical path for compact, lightweight, low cost design. The most important thing is that the laser communication should have low wave aberration, low polarization loss and high isolation. Transmitting and receiving signals use one optical path, which makes negative influence on the isolation in system. It is a big challenge for engineers or designers to ensure the high isolation. The paper made a design about the key device in the transceiver, which was sensitive to isolation. The basic idea of this design was using the special structure style and optical material. It could eliminate stray light efficiently. It was proved that the process of manufacturing and assembling was not difficult. The device proposed in this paper could improve the efficiency and quality of laser communication. Moreover, the paper made mechanical simulation of device to prove that the device was safe.

A new way to generate Airy beam through quasi-phase-matched (QPM) Pockels effect in a 2-dimensional (2D) quadratic nonlinear photonic crystal (QNPC) is presented. Taking advantage of binary modulation, one can fabricate such a 2D QNPC, in which the QPM condition for Pockels effect is satisfied along x-axis, while the cubic phase for Airy beam is imposed along y-axis. When a Gaussian beam propagates along x-axis of the 2D QNPC with an external electric field, the QPM Pockels effect takes place, resulting in an generated wave with Airy beam’ Fourier spectrum. When performing an optical Fourier transform (FT) on the output, we can obtain the desired Airy beam. Thanks to the QPM Pockels effect, the intensity of Airy beam can be modulated efficiently, which is applicable in optical communication. The generation and modulation of Airy beam can be achieved simultaneously in a single chip, which is advantageous for integration. It should be noted that, this method can also be employed for the other desired wave-front and provides full control of the intensity of the generated beam.

Laser command guidance system transmits commands via pulsed laser, which has the advantages of long transmission distance and high reliability. In this paper, the error correction encoding method during the transmission of pulse command is analyzed and verified through experiments on the laser command guidance system. The experimental system consists of a controller, an encoded laser transmitter, a laser receiver and decoder, a solution drive and a data collector. The basic principle of Hamming code which can realize the detection of 2 error codes on the basis of 1 error code corrected is also analyzed. Experiments of laser command transmission, reception and decoding carried out on the experimental system validated the feasibility and error correction accuracy of the experimental system.

The laser-beam riding guidance system controls the way a missile flies and hits a target by encoded laser information field. This paper discusses the spatial encoding method of the modulating disk in the laser beam riding guidance system and designs a light field modulation optical system for the transmitter of the laser beam riding guidance system. The reshaped laser beam can be projected into the internal and external code channels of the modulating disk, thus generating an encoded information field which will be used to control the flight of a missile. Besides, this paper designs a distributed photo detector light field collection system to simultaneously test the light field modulation status of the information field. This system is composed of modules including a pinhole aperture array, a PIN array, a signal processing electric circuit and a data collecting and processing module. The result demonstrates the accuracy and feasibility of the modulated light field test carried out with this system.

In this work, a 12-tupling frequency millimeter wave generation scheme based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) is proposed. A dual parallel Mach Zehnder modulator (DPMZM) is used to generate pure 2^nd order optical tones which are sent into a SOA to realize the 2^nd order and 6^th order optical sideband output due to the effect of the FWM. An optical filter is employed to filter out 2^nd order optical tone and the pure 6^th order optical sidebands are obtained. A 12-tupling frequency millimeter wave can be generated by beating the 6^th order optical sidebands in the photodetector (PD). The working principle of the system is analyzed in detail, and the feasibility of the scheme is verified in the simulation results.

Mine accidents are frequent, miner safety and machine production was an important thing in the mine. Real-time communication and positioning one of the necessary things in mine, but he interference and shielding of rf signal are serious in mine scene. Optical wireless technology can be used underground to provide communication and location for miners. In this paper, the research status of optical wireless technology in mines is summarized, from the communication and location of two aspects and the application of sensing technology and robot wireless and wired optical in mines. Finally, the prospect of optical wireless technology in mines is summarized.

As one of the most important applications of 5G technology, vehicle scenarios have strict requirements in end-to-end delay, reliability and data rate. Based on the huge advantages of free space Optical (FSO) communication technology, this paper summarizes the research status of vehicle FSO communication under the 5G evolution background, by integrating satellite, air, ground and underwater communications into a unified wireless network through unmanned vehicle platforms, the research progress of "space, earth and sea integration" optical transmission link is built to realize fast, stable and large-capacity data transmission system. The technical challenges of vehicle FSO communication faced with are also discussed and its future development is prospected.

Wireless optical communication (WOC) has been widely concerned by the industry due to its advantages of wide bandwidth, high transmission rate, better security, and no need of authorized spectrum. As the fifth generation communication and beyond five generations the rapid development of communication system, and to give full play to the advantages of WOC, this paper reviews the relay technology under indoor wireless optical communications, outdoor wireless optical communications and underwater wireless optical communication, elaborates based on relay technology of the three methods of communication protocol, channel model and modulation method, combining with specific experimental analysis of its performance. Finally, main problems of relay WOC are pointed out and the potential solutions are also given.

Radial polarization (RP) and azimuthal polarization (AP) components in vector vortex beams own orthogonal polarization directions and are different in many functions. Thus, the splitting of AP and RP is required in detailed applications. This work presents to split a vector vortex beam into AP and RP by using a highly commercial S-waveplate. This approach is simple and the light losses are low. The configurations and principle of this approach are elaborated.

Aiming at the problem that the great spatial correlation between sub-channels of the underwater visible light MIMO system affects the system's error performance, a precoding algorithm based on lattice reduction is proposed. The lattice reduction algorithm makes the channel matrix more orthogonal through iterative reduction operations. The transformation matrix is used as the precoding matrix to precode the transmitted signal, which is equivalent to transmit the original signal on the channel with less correlation. It can be used for transmission to improve the signal detection performance of the system. The lattice reduction algorithm is further combined with the linear precoding algorithm to compensate for the amplification of noise caused by linear detection at the receiving end, so that the system has better error performance. The simulation results show that at a bit error rate of 10^-4, compared with a system without precoding, the required signal-to-noise ratio of the system using the lattice reduction precoding algorithm is reduced by about 10dB, compared with the traditional minimum mean square error precoding, the required signal-to-noise ratio of the system using the minimum mean square error precoding based on lattice reduction is reduced by about 6dB.

In the interference test process of a parallel flat optical element, the light beam after multiple reflections on the front and rear surfaces of the element with the wavefront to be measured often cause multi-surface interference, forming spurious fringes on the interferogram, which will introduce large errors to the wavefront measurement. Spurious fringes mainly have a great impact on the parameters such as wavefront gradient root mean square (GRMS) and mid-spatial-frequency power spectral density (PSD). The RMS value of the wavefront containing spurious fringes is generally significantly larger than the true value, which will affect the accurate measurement and evaluation of the wavefront quality of optical components. Existing spurious fringes suppression methods often have the disadvantages of multiple adjustment steps in the test process or high hardware requirements, and it is difficult to match the requirements for rapid and high-efficiency test of high-precision optical flat components. This paper proposes a method for removing spurious fringes in interference test based on characteristic spectrum band-stop filter, which can achieve accurate removal of spurious fringes. First, by using the ZoomFFT algorithm to zoom up the spectrum of the wavefront data points, the effective identification of the spectral characteristics of the spurious fringe is realized; then the band-stop filter in a specific area is used according to the spectral characteristics of the spurious fringes, only the frequency spectrum of the spurious fringes is removed, and the wavefront data of the component to be tested is completely retained without changing its own shape; the Quad-Flip operation and error function filter window are used for spectrum filtering, which effectively reduces Gibb's noise in the frequency domain due to the sudden truncation of the input data edge during FFT transformation. The transmitted wavefront of a fused silica element with a diameter of Φ100mm was tested on the ZYGO static interferometer, and the test results contained a large number of spurious fringes. After processing by this method, the spurious fringes were removed. The mid-spatial-frequency wavefront RMS of the component is reduced from 5.365nm to 3.678nm. The method does not need to add additional hardware and tedious measurement and adjustment operations, the calculation is fast, and the spurious fringes removal is accurate.

In this work, a designed fractionally spaced equalizer (FSE) is introduced to the visible light communication (VLC) system using multi-carrierless amplitude phase (m-CAP) modulation to suppress the high-frequency fading. The bit error ratio (BER) performance of the VLC system with FSE at different transmission rates, signal noise ratio (SNR) condition and QAM order is investigated and compared with that with SSE. The simulation results show the performance of m-CAPVLC system can be improved by using FSE. As a result, when T/2 FSE and T/4-FSE are used, 73Mb/s and 90Mb/s transmission rate can be obtained under the condition of 18dB SNR, respectively.

When we use FBG to filter the optical signal, we pay more attention to its optical power spectrum and less attention to its dispersion fluctuation. However, if the dispersion fluctuation of FBG is too large, it may lead to signal distortion, so it is very important to detect the dispersion fluctuation of FBG. In this paper, we choose the FBG with wavelength of 1550nm and reflectivity of 95%, and use the method of phase to amplitude conversion to detect the second-order dispersion fluctuation of FBG. In the temperature range of 23 ° - 33.6 °, we have measured the optical power spectrum and the second-order dispersion fluctuation curve of the fiber grating, and analyzed the experimental results. Then we find that when the FBG with flat optical power spectrum but large dispersion fluctuation is used for filtering, the output signal will be distorted.

A degenerated look-up table based perturbative nonlinearity compensation (DLUT-PNC) algorithm for probabilistically shaped 16QAM signals was proposed to compensate intra-channel fiber nonlinearity. However, this method adopts the standard 16 QAM signals without considering the influence of ASE noise to calculate the degenerated elements of table. Hence, the degenerated elements of the table are not strictly optimal. In this paper, a blind adaptive DLUT-PNC (BADLUT- PNC) method based on the gradient descent algorithm is proposed. We use the gradient descent algorithm to optimize the degenerated elements and then obtain the optimal degeneration scheme. In a single channel 70GBaud dual-polarization 16QAM transmission simulation with a 1200km link, the proposed scheme is investigated. The simulation result shows that the extra 0.15~0.45dB SNR improvements can be achieved by adopting our proposed BA-DLUT-PNC compared to the conventional DLUT-PNC method.

With the construction of the new generation of intelligent optical network, the demand for ROADM (Reconfigurable Optical Add-Drop Multiplexer), which is composed of WSS (Wavelength Selective Switch) and MCS (Multicast Switch), is increasing rapidly. Aiming at the 1 × N-channel optical switch, which is the core component of MCS, a technical scheme based on optical waveguide array and MEMS micromirror is proposed in this paper. The optical waveguide array with bending transition part is used as the input / output channel instead of the traditional optical fiber array, which can control the crosstalk and greatly reduce the off-axis amount of the edge channel. At the same time, two collimating lenses are used to further reduce the off-axis aberrations of the edge channels to achieve more output channels.

Consider the evolution of the wander and M2-factor of Mathieu Gaussian-Schell beam in turbulent ocean. We develop models for wander and M2-factor of this beam based the theory of wigner distribution function. The influences of the oceanic parameters on the wander and M2-factor are discussed in detail. It is found that as the propagation distance, the dissipation rate of temperature variance, the eddy diffusivity ratio and ratio of temperature and salinity contributions to the refractive-index spectrum increases, both M2-factor and beam wander increase; but M2-factor and beam wander increase with the decreasing of initial beam width, the kinetic energy per unit mass of fluid. However, as the variation of ellipticity factor and OAM quantum number increase, the evolution of M2-factor and beam wander are some complexes. The influences of coherent width of light source and wavelength on the M2-factor and beam wander are negligible. Our results are helpful in the design of an optical communication system in an oceanic environment.

The silicon Mach–Zehnder modulator is a significant type of optical modulator, which is widely utilized in optical communication and microwave photonics. The performance of the second harmonic microwave generation by a silicon Mach–Zehnder modulator is simulated and analyzed. The power and the purity of the second harmonic microwave mainly depend on two significant parameters: 1) the electrical nonlinearity of the diodes on arms of the modulator, 2) the bias voltage on the diode. Simulations show following results:1) when the built-in voltage Vb decreases from 8V to 3.5V, the incremental amounts of second harmonics and the fourth harmonics are 7.9dB and 15.6dB under the condition that the RF power is 15dBm and the bias voltage is 0V; 2) when the bias voltage increases from -0.5V to 4V, the ratio between second harmonics and the fourth harmonics varies from 20.0dB to 11.3dB under the condition that the RF power is 15dBm and the built-in voltage Vb is 3.5V. 3) when the RF power increases from 5dBm to 20dBm, the ratio between second harmonics and the fourth harmonics varies from 27.6dB to 11.6dB under the condition that is the bias voltage is 2V and the built-in voltage Vb is 3.5V. To conclude, the powers of second harmonics will increase with the reduction of the ratios between the second harmonics and the fourth harmonics.

A time-domain blind inter-carrier interference (ICI) compensation method is proposed for coherent optical offset-quadrature amplitude modulation based filter-bank multicarrier (CO-FBMC/OQAM) system. The numerical simulation results verify that the proposed method has a significant improvement of linewidth and symbol duration product tolerance than the modified blind phase search (M-BPS) in the CO-FBMC/OQAM system.

Based on the principle of space-time duality, time lens can be used for reference in theoretical research and practical application. As an optical device, the advantages of time lens lie in its simple structure and diversified functions. So far, the time lens has realized the functions of broadening, compressing, Fourier transform and time reversal of optical signal waveforms. In this paper, the time reversal function of the time lens imaging system is used to realize the effect of the optical logic "NOT" gate, which greatly simplifies the logical "NOT" operation system and greatly improves the operation speed. The research on the use of the optical logic "NOT" gate as Manchester code signal generator is also carried out.

With the vigorous development of data centers, optical fiber interconnection technologies have been evolved from multimode optical fiber (MMF) parallel transmission to CWDM4 single-fiber bidirectional (Bidi) transmission. What’s more, requirements for miniaturization of optical transceivers are put forward. This paper studies a CWDM4 Bidi transceiving module based on hybrid integration technology. Six optical interleavers in serial and parallel connection function as the CWDM4 wavelength division multiplexer and demultiplexer, while an optical circulator is designed with the three inputs/outputs at the same side, which helps to realize Bidi transmission. The former is based on integrated optics and the latter is based on micro-optics. Through the hybrid integration of integrated optics and micro-optics technologies, the transceiving module is minimized and can be integrated into a QSFP module.