A system with a spatial light modulator in a cycling structure is designed to realize holographic display. The light is controlled to pass through SLM sequentially for certain times, to get high quality diffraction.

Liying Tan;Yubin Cao;Kangning Li;晶 马

2017

The optical image encryption has attracted more and more researchers' attention, and the various encryption schemes have been proposed. In existing optical cryptosystem, the phase functions or images are usually used as the encryption keys, and it is difficult that the traditional public-key algorithm (such as RSA, ECC, etc.) is used to complete large numerical key transfer. In this paper, we propose a key distribution scheme based on the phase retrieval algorithm and the RSA public-key algorithm, which solves the problem for the key distribution in optical image encryption system. Furthermore, we also propose a novel image encryption system based on the key distribution principle. In the system, the different keys can be used in every encryption process, which greatly improves the security of the system.

Tieyu Zhao;Qiwen Ran;Lin Yuan;Yingying Chi;晶 马

Mathematical Problems in Engineering

2015

Combining the advantages of OFDM technology with the coherent detection, the bit error rate (BER) performance of coherent OFDM FSO system was studied, and the influence of OFDM mapping mode and mapping order on the symbol error of the system was taken into account. In Gamma-Gamma atmospheric turbulence channel model, the bit error performance of three cases of weak, moderate and strong turbulence were taken into consideration separately from the perspective of the average signal-to-noise ratio and the required average received optical power. On this basis, the closed form expression of the symbol error rate was deduced. Simulation results show that the coherent detection OFDM FSO system can better overcome the effects of atmospheric turbulence, in weak and moderate turbulence, the system BER performance with QAM mapping mode is obviously better than that of PSK mapping mode, however, under the strong turbulence the advantage is not very obvious. In addition, with the increase of mapping order, system symbol error rate increases, so in practice it can improve the system BER performance by reducing the number of mapping order.

Yi Wang;Shuai Yang;晶 马;Liang Shan

Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering

2016-7-25

For very high data rates, intersatellite optical communications hold a potential performance edge over microwave communications. Acquisition and Tracking problem is critical because of the narrow transmit beam. A single array detector in some systems performs both spatial acquisition and tracking functions to detect pointing errors, so both wide field of view and high update rate is required. The past systems tend to employ CCD-based camera with complex readout arrangements, but the additional complexity reduces the applicability of the array based tracking concept. With the development of CMOS array, CMOS-based cameras can employ the single array detector concept. The area of interest feature of the CMOS-based camera allows a PAT system to specify portion of the array. The maximum allowed frame rate increases as the size of the area of interest decreases under certain conditions. A commercially available CMOS camera with 105 fps @ 640×480 is employed in our PAT simulation system, in which only part pixels are used in fact. Beams angle varying in the field of view can be detected after getting across a Cassegrain telescope and an optical focus system. Spot pixel values (8 bits per pixel) reading out from CMOS are transmitted to a DSP subsystem via IEEE 1394 bus, and pointing errors can be computed by the centroid equation. It was shown in test that: (1) 500 fps @ 100×00 is available in acquisition when the field of view is Imrad; (2)3k fps @ 10×10 is available in tracking when the field of view is 0. Imrad.

Si Yuan Yu;晶 马;Li Ying Tan

Proceedings of SPIE - The International Society for Optical Engineering

2005

An optical wireless personal area communication system supporting multiple users is experimentally demonstrated based on 16-CAP modulation combined with TDM. Error-free communication is achieved with 10 Gb/s data rate for up to 10 users.

Tingting Song;Ke Wang;Ampalavanapillai Nirmalathas;Tian Liang;Elaine Wong;晶 马

2017-1-23

In this paper, a quantum color image encryption scheme based on coupled hyper-chaotic Lorenz system with three impulse injections is proposed. Firstly, in order to enhance the complexity of trajectory, three impulse signals values are injected into coupled hyper-chaotic Lorenz system during iterations. Then, six sequences generated from this system are used to encrypt red, green and blue components of the quantum color original image by XOR operations and right cyclic shift operations. Six initial values and three impulse signals values are used as keys, which could reduce the burden of keys transmission and make the cryptosystem own a key space large enough to resist exhaustive attack, even the attack from a quantum computer. Numerical simulations demonstrate that the proposed encryption scheme has a good feasibility and effectiveness for protecting quantum color images and is more secure in comparison with other encryption algorithms.

Qiwen Ran;Ling Wang;晶 马;Liying Tan;Siyuan Yu

Quantum Information Processing

2018-8-1

In intersatellite optical communications it is important to obtain the most efficient performance of acquisition system with respect to acquisition time for a given probability. In this paper a novel approach to the analytical optimization of spatial acquisition is presented as an alternative of the conventional Monte Carlo simulation. First, an analytical expression of estimating mean acquisition time (MAT) is derived as a function of the desired acquisition probability, taking into account the distribution function of satellite position, field of uncertainty (FOU), beam divergence angle and dwell time. Accordingly, the analytical expression of multi-scan, which is always adopted by practical optical terminals to ensure the acquisition success, is also presented. Then, by minimizing the MAT of multi-scan, the optimum ratio of the FOU θ_Uto the pointing error deviation σis obtained, which is θ_U/σ=1.3 . An example for a practical intersatellite acquisition between a Low Earth Orbit Satellite and a Geostationary Earth Orbit Satellite is given. And the theoretical result calculated by the proposed analytical expression is approximately equal to the result by Monte Carlo simulation. The results can be used in designing acquisition system for the intersatellite optical communications.

Xin Li;Siyuan Yu;晶 马;Liying Tan

Optics Express

2011-1-31

In practice, due to the reasons related to the laser device and the inevitable error of the processing technique, a laser source emitted from a communication terminal is represented by partially coherent laser source. The fiber-coupling efficiency and the incident optical power at the receiver aperture are affected by the source coherent parameter ζ through atmospheric turbulence. In this paper, the statistical distribution of both the fiber-coupling efficiency and the incident optical power are given, based on which the effect of the source coherent parameter ζ on the performance of fiber-coupling differential phase-shift keying (DPSK) receiver is systematically analyzed. The system fade margin, the average bit error rate (BER) and the power penalty are obtained in the presence of the degradation of the source coherent degree. The results manifest that the performance of fiber-coupling DPSK receiver system degrades drastically with increasing source coherent parameter ζ. The hope of this work is to improve the redundancy design of fiber-coupling DPSK receiver system.

Mengnan Li;Liying Tan;Qingbo Yang;晶 马;Siyuan Yu

Optics Communications

2015-9-1

A black box model (BBM) of common environment is introduced to characterize the gain of erbium-doped fiber amplifier (EDFA) for any wavelength in the range of 1540-1560 nm in the radiation environment. Two erbium-doped fibers with different concentrations have been radiated to confirm the validity of the BBM. Using the method of BBM, the less measured parameters can overcome the restriction of the measured time in radiation environment. Therefore, that affords a new way to characterize the gain deterioration characteristic of EDFA in multiwavelength in radiation environment.

Mi Li;晶 马;Xuping Zhang;Yuejiang Song;Wenhe Du

Journal of Lightwave Technology

2012

In practice, due to reasons related to the laser device and the inevitable error of the processing technique, a laser source emitted from a communication terminal is partially coherent, which is represented by the Gaussian Schell Model (GSM). In a space-to-ground optical communication link, the cross-spectral density function, based on the Gaussian Model in previous research, is replaced by GSM; thus, the fiber-coupling efficiency equation of the GSM laser source is deduced. The GSM equation presents the effects of the source coherent parameter ζ and the zenith angle θ on the fiber-coupling efficiency, which were not included previously. The effects on the fiber-coupling efficiency are numerically simulated and analyzed. The results manifest that the fiber-coupling efficiency invariably degrades with increasing ζ or θ. The hope of this work is to improve the redundancy design of fiber-coupling receiver systems by analyzing the fiber-coupling efficiency with the source coherent parameter.

Liying Tan;Mengnan Li;Jiajie Wu;晶 马;Qingbo Yang

Optics Communications

2015-8-15