一种新型波长转换器的模块化设计

对一种新型结构全光波长转换器进行了高精度、高稳定度的模块化设计，并利用该模块实现对波长转换器参数的监控。结果表明这种新型模块对波长转换器的实现提供了可靠的保证，表现出较高的稳定度和实用性。     

全光网中基于FBG的OADM设计研究

提出一种全新的OADM(Optical Add—Drop Multiplexers)结构设计，此结构仅采用一个多端口环行器，大大减少了环行器的数量，节约了成本。若要上／下路一个波长．则只需要一个FBG(Fiber Bragg Grating)；若要同时上／下路多个波长，则需要2m个FBG。计算机仿真实验证明此结构比H．Yuan提出的结构具有更低的损耗．对全光网络的实现具有重大的意义。     

Photochromic Free MOF‐Based Near‐Infrared Optical Switch

We demonstrate herein an all‐optical switch based on stimuli‐responsive and photochromic‐free metal–organic framework (HKUST‐1). Ultrafast near‐infrared laser pulses stimulate a reversible 0.4 eV blue shift of the absorption band with up to 200 s^?1 rate due to dehydration and concomitant shrinking of the structure‐forming [Cu₂C₄O₈] cages of HKUST‐1. Such light‐induced switching enables the remote modulation of intensities of photoluminescence of single crystals of HKUST‐1 as well visible radiation passing through the crystal by 2 order of magnitude. This opens up the possibility of utilyzing stimuli‐responsive MOFs for all‐optical data processing devices.     

基于非线性光纤环形镜的少模脉冲幅度调制再生器

随着网络带宽需求的快速增加,波分复用系统的容量已接近非线性香农极限.为了适应未来网络的发展,空分复用技术引起了越来越多的关注.本文首次提出基于少模非线性光纤环形镜(FM-NOLM)的脉冲幅度调制(PAM)全光再生器,描述了其工作原理和具体设计过程.采用COMSOL软件对组成FM-NOLM的硫化物高非线性光纤进行了模式特性仿真.以LP01,LP11,LP21三个光纤模式为例,确定了再生器的参数,计算出每个模式的功率转移函数曲线.仿真分析了该少模PAM-4全光再生器的噪声抑制(NRR)性能,并与单模情形进行了比较.研究表明,1)对于每个空间模式的PAM信号,所有再生电平具有一致的功率转移性能;2)当输入信噪比(SNR)约大于20 dB时,三种模式的噪声抑制比均可超过3 dB,并随着输入信噪比线性增加,其斜率约为1.2;3)在相同输入SNR条件下,三种模式的噪声抑制比相差不大,不超过1.1 dB.为了说明再生器的再生性能,当输入SNR为25 dB时,我们还给出了再生前后PAM-4信号的功率分布直方图.与现有的再生方案相比,本文方案的均匀多电平再生转移性能,使其更适合高频谱效率的长距空分复用系统和任意电平数的PAM信号再生.此外,该方案也能够扩展到波长域,有效提高光通信系统的传输容量.     

半导体光放大器的光-光互作用及其应用

半导体光放大器（SOA）中的非线性系数约为普通光纤的10^9，为光子晶体光纤的10^7，而且有4种光-光互作用，即交叉增益调制（XGM）、交叉相位调制（XPM）、交叉偏振调制（XSM）及四波混频（FWM），可以灵活地组成各种光信号处理器件，如波长变换器、全光触发器、全光逻辑、全光时钟恢复、全光缓存器……等，正成为整个光信号处理的基础。文章介绍了它们的原理和简单应用。     

Setup of a dipole trap for all-optical trapping

Micromotion induced by the radio-frequency field contributes greatly to the systematic frequency shifts of optical frequency standards. Although different strategies for mitigating this effect have been proposed, trapping ions optically has the potential to provide a generic solution to the elimination of micromotion. This could be achieved by trapping a single ion in the dipole trap composed of a highpower laser field. Here, we present the setup of the dipole trap composed of a 532 nm laser at a power of 10 W aiming to optically trap a single ~(40)Ca~+ and we observe an AC-Stark shift of the fluorescence spectrum line of ～22 MHz caused by the 532 nm dipole beam. The beam waist of the dipole laser is several microns, which would provide a dipole potential strong enough for all-optical trapping of a single ~(40)Ca~+ ion.     

冷原子介质中基于相干诱导高反射带和高透射带的全光路由控制

以相干诱导光子带隙结构为工作基础,提出了一种可对两个弱光信号的传播路径同时进行动态调控的新型全光路由控制方案。利用描述光波在空间周期介质中相干散射的传输矩阵理论,结合描述单频激光与多能级原子共振相互作用的密度矩阵方程,计算了作为控制媒介的相干驱动超冷原子系综的稳态反射光谱和稳态透射光谱。结果表明,通过改变两个较强相干激光的空间模式、强度和频率等参数,可在探测跃迁共振频率附近建立反射率约为95%或者透射率约为95%的两个特殊频带。对这样的相干诱导高反射带和高透射带进行了实时动态调控,可根据需要引导两个不同频率的弱光信号进入指定的网络通道。该方案很好地满足了在量子信息处理领域对弱光信号进行全光路由控制时的低损耗和低形变要求。     

低功耗非线性光纤光栅全光开关

全光开关是未来全光通信和光计算机的关键器件.已经研究过的全光开关的种类很多,其中光纤光栅全光开关最容易与光纤系统匹配.文章首先陈述两种基于普通石英光纤的单光栅全光开关,即光纤布拉格光栅(FBG)全光开关和长周期光纤光栅(LPFG)全光开关,这两种低非线性的光开关要求千瓦量级的高开关功率,故不宜应用;然后重点介绍两种高非线性的光纤光栅全光开关,它们分别由单个高非线性FBG和用高非线性光纤连接的LPFG对构成.文章所介绍的非线性光纤材料是以掺稀土石英光纤为例.这两种高非线性的光纤光栅全光开关具有毫瓦量级的低开关功率,有可能获得实际应用.     

Method of developing all-optical parallel to serial converter exploiting Kerr non-linearity of medium

Different all-optical logic operations, memory blocks etc. are developed using the inherent parallelism of optics. In any digital communication and computation system, the role of serial to parallel and parallel to serial data conversion are very much essential for making a data convenient for transition.Here in this paper, the authors propose a new scheme for developing an all-optical parallel to serial data conversion system by using optical J-K Flip-Flops and some logic gates based on optical non-linear switches. The uses of such switches are widely established in the area of optical parallel computation.This process can be extend for developing some all-optical digital devices like shift register, optical pulse counters etc. The proposed scheme deals with the best use of high parallelism of the optics, so the super-fast processing speed can be achieved.     

Routing of 2-D switching networks by their embedding into cubes

The proposed all-optical 2-D switching networks are (i) M×N-gon prism switches (M2, N3) and (ii) 3-D grids of any geometry N3. For the routing we assume (1) the projection of the spatial architectures onto plane graphs (2) the embedding of the latter guest graphs into (in)complete host hypercubes (N=4) and generally, into N-cube networks (N3) and (3) routing by means of the cube algorithms of the host. By the embedding mainly faulty cubes (synonyms: injured cubes, incomplete cubes) arise which complicate the routing and analysis. The application of N-cube networks (i) extend the hypercube principles to any N3 (ii) increase the number of plane host graphs and (iii) reduce the incompleteness of the host cubes. Several different embeddings of the intersection graphs (IGs) of 2-D switching networks and several different routings are explained for N=4 and 6 by various examples. By the expansion of the grids (enlargement) internal waveguides (WGs) and internal switches are introduced which interact with the switches of the original 3-D grid without increasing the number of stages (NS). The embeddings by expansion apply to interconnection networks whereas dilation-2 embeddings (dilation ≡ distance of the nearest-neighbour nodes of the guest graph at the host) are rather suitable for the emulation of algorithms. Concepts for fault-tolerant routing and algorithm mapping are briefly explained.