相位共轭实现光学逻辑运算

本文从麦克斯韦电磁场理论出发,给出了用四波混频相位共轭波和泵浦光波及入射物波偏振态之间的关系来实现光学逻辑运算的途径。     

非完全相位共轭特性研究

实验研究了部分相位共轭的特性,实验表明非完全相位共轭对相位共轭保真度及相位共轭光的能量集中度具有一定的影响,在没有吸收的情况下,根据能量守恒和互逆原理,推导了相位共轭保真度和相位共轭镜的有限尺寸之间的简单关系。     

光学元件列阵的准相位共轭特性

光学元件列阵的准相位共轭特性使其能消除波前畸变和介质扰动,成为真正实用的准相位共轭器。因此,近年来这方面的理论和实验研究进展迅速。本文从几何光学和波动光学两方面概述其基本原理,并对实验进展和实际应用作一综述。     

光学元件列阵的赝相位共轭特性及其研究进展

由光学元件组成的列阵,其综合成像不同于单元成像,具有赝相位共轭将性。本文对有关这一领域的研究作了综述。     

相位共轭光腔研究进展

相位共轭光腔能消除腔内的波前畸变和介质扰动，从而能提高输出激光束的性能和质量，本文对近年来这一领域的理论和实验研究作了概述。     

采用简单泵浦相位共轭镜实现的光学关联存储器

本文设计了一种结构简单的相位共轭镜,并用KNSBN:Ce光折变晶体作为存储介质和相位共轭镜实现了光学关联存储。文中给出了有关的实验结果。     

用相位共轭技术实现区域目标的激光传输畸变补偿

相位共轭技术通过“时间反演”过程进行激光传输畸变补偿，具有快响应、高灵敏度、高稳定性，以及结构简单、价格低廉等优点。但通常主动信标光，采用相位共轭方法难以实现区域目标的大气传输畸变补偿。本文介绍我们首次提出了解决方案－成象减裁加阈值共轭镜，并用ＢａＴｉＯ３自泵浦相位共轭镜对静太和模拟湍流畸变进行了原理性实验。     

大信号布里渊增强四波混频相位共轭镜

对大信号偏振去耦布里渊增强四波混频(BEFWM)相位共轭光的输出特性(波形、束散角、能量转换效率等)进行了系统的研究。结果表明,使布里渊增强四波混频工作在大信号强相互作用状态下,可以很好地克服同等抽运及结构条件下小信号布里渊增强四波混频中经常出现的波形调制现象,具有良好的波形稳定性以及输入输出脉冲的波形相关性;输出光相位共轭保真度接近100%,且在不同注入信号强度下几乎保持恒定;大信号布里渊增强四波混频能量转换效率相对小信号情况也有很大的提高。     

基于光学相位共轭的数字化波前整形技术（特邀）

光在生物组织中传播时,会被微观尺度上不均匀的组织随机散射,这种现象严重制约了光学技术在生物医学中的应用。波前整形技术将散射过程当成一个确定性的过程,通过测量散射效应造成的相位延迟并利用空间光调制器进行逐点补偿,可以实现散射光的操控与重新聚焦。在各类波前整形技术中,基于光学相位共轭的数字化波前整形技术具有可调控自由度高、系统响应速度快等优点,最适宜与生物医学应用相结合,如生物活体成像、操控、治疗等。文中将重点关注基于光学相位共轭的数字化波前整形技术的发展,探讨该技术在应用研发中面临的主要技术瓶颈和挑战,并概述其应用开展情况。     

Dispersion compensation by optical phase conjugation in silicon waveguide

The use of a silicon-waveguide-based optical phase conjugator at the mid-span of a fibre link for dispersion compensation is experimentally demonstrated, enabling transmission of optical data at up to 40 Gbit/s over 320 km of standard fibre with clear open eye diagrams at the receiver. In addition, the feasibility of dispersion compensation for multiple DWDM channels simultaneously is demostrated. A signal conversion efficiency of -10 dB is obtained with a pump intensity of 37.5 MW/cm² in the waveguide.     

利用相位共轭实现单根光纤直接传输图象

利用相位共轭介质——光折变晶体掺铁铌酸锂(Fe:LiNbO_3)产生的简并四波混频的波前反转性质,补偿了多模光纤由于模色散引起传输图象的畸变,实现单根多模光纤直接传输图象;研究了相位共轭对传输图象光场偏振态的影响。     

WDM transmissions exploiting optical phase conjugation

Due to the frequency shift occurring in the process of optical phase conjugation (opc) generation, the application of opc in multiple-channel transmission is limited severely by the third-order dispersion. In this paper, taking into account the influence of the frequency shift and the compensation of nonlinear effects, we present an effective method to optimize the dispersion map for broad-band transmissions using optical phase conjugation. The numerical simulation results show that high efficiency wavelength-division-multiplexing (wdm) transmissions can be achieved by using the combination of opc with an optimized dispersion map.     

Coplanar waveguide phase shifter controlled by a spatially periodic optical illumination

The characteristics of a periodically-illuminated CPW phase shifter are investigated by the spectral domain approach combined with the cascaded transmission line matrix method. It is found that the phase shifter characteristics can be improved by appropriate use of periodic illumination instead of uniform illumination.     

Nonlinear noise amplification in optical transmission systems with optical phase conjugation

Taking into account the influence of group-velocity dispersion (GVD) and the nonlinear Kerr effect, the nonlinear amplification of the amplified spontaneous emission (ASE) noise in fiber transmission systems using optical phase conjugation (OPC) is studied. Under a path-averaged power approximation for long-haul transmission systems, an equivalent system is developed to evaluate ASE noise amplification and accumulation in OPC systems. Combining the theoretical analysis and numerical simulations, the noise suppression effect in OPC systems is demonstrated and discussed. By using the numerical calculation method, the power variation along the system is involved in the evaluation of noise amplification. It is shown that the power variation through the system results in an imperfect compensation of the modulation instability (MI) effect, which furthermore causes the degradation of the noise suppression performance in OPC systems with anomalous dispersion.     

Techniques for nonlinearity cancellation into embedded links by optical phase conjugation

One of the main causes of signal degradation in high-bit-rate transmission systems is the interplay between fiber nonlinear effects and dispersion. Different techniques to compensate nonlinear effects in transmission systems, by using an optical phase conjugator, have been proposed in the literature. In this paper, two different innovative setups allowing nonlinearity cancellation in an embedded link are disclosed. The proposed schemes are simpler than those previously described and strongly improve systems performances. The physical mechanism allowing nonlinearity compensation is depicted, and the effectiveness of the proposed solutions is numerically demonstrated. Moreover a new practical method, useful for performance optimization of systems including a phase conjugator, is presented. Results apply to any bit-rate and modulation format.     

受激喇曼后向散射波的位相复共轭特性

本文报导了受激喇曼后向散射波的位相复共轭特性的研究,实验结果表明受激喇曼后向散射波是泵浦波的位相复共轭。我们在实验上得到了由这种位相复共轭获得的泵浦波的预期的再现象。讨论了受激喇曼后向波位相复共轭散射波产生的条件。     

Study of optical phase conjugation in bulk traveling wave semiconductor optical amplifier

Optical phase conjugation (OPC) in a bulk SOA has been optimized both under static and dynamic conditions. Conjugation with gain has been obtained. Dynamic optimization leads to a compromise between conversion efficiency and signal-to-background (S/B) ratio, providing that the modulated signal is kept a minimum of 5 dB weaker than the pump to avoid detrimental saturation effects. Transparent 10-Gb/s phase conjugation with extinction ratio around 20 dB at moderate power levels is reported.     

Microwave phase shifter using optical waveguide structure

A microwave phase shifter with an integrated optics structure with high efficiency is discussed. The structure and the performance of the device are discussed. Microwave phase shifting was carried out using the fabricated phase shifter of titanium diffused LiNbO₃ optical waveguides. The measured voltage to obtain halfwave phase shift for a 800 MHz microwave signal was 7.0 V. The input microwave power was 21 dBm, and the detected output microwave power was -24 dBm, so the microwave insertion loss was calculated to be approximately -45 dB. The optical insertion loss of the device was -12 dB