Curvature investigation in tapered fibers and its application to sensing and mode conversion

Non-adiabatic tapered fibers are basic photonic components used in a wide range of applications. Here we investigate a way to increase their utility through the controllable bending of one of their tapered sections. The experiments carried out explain, for the first time, the mechanics of this approach showing how these tapers can be used to build more sensitive sensors. Their use as highly efficient mode converters is also discussed.     

在BEPC上建造γ束线站的分析

考虑电子的反冲并利用康普顿散射,研究了激光同步辐射光源(LSS)辐射的光子波长、光子能量。结果表明,对于不同的γ,LSS辐射的光子波长和能量有不同的近似公式。当γ<<λ1/4λe时,LSS辐射的光子波长λ2≈λ1/4γ2,能量(εc2≈4γ2εc1;当γ>>λ1/4λe时,LSS辐射的光子波长λ2≈λe/γ,能量cε2≈m0γc2;结果表明,LSS辐射的条件是种子激光的波长λ1大于电子的物质波波长λm;LSS辐射的极值波长是λ2m ax=h/m0γv,极值能量是cε2m ax=βeε;本文后半部分提出了利用北京正负电子对撞机的强流高亮度电子束与激光的康普顿背散射产生单色γ射线的建议。     

一种新型可调谐锁模光纤激光器

利用法布里-珀罗腔的激光二极管作为调制器件，实现环形腔光纤激光器的主动锁模。并利用法布里-珀罗腔的激光二极管的多纵模特性，把激光二极管当作一梳状滤波器，通过偏振控制器来调整入射到激光二极管内光的偏振态，同时均衡腔内增益，得到波长大范围可调谐的锁模激光，其脉冲宽度约为48ps，脉冲重复速率2GHz。     

光纤光栅激光器激射波长的研究

一般认为，用光纤光栅作选频元件的光纤激光器，激射波长与光纤光栅中心反射波长一致，本文报道了不同的实验研究结果。通过细致的实验研究，发现光纤光栅激光器激射波长相对于光纤光栅中心反射波长有一定的偏移。激射波长可以出现在光栅中心反射波长的长波端，也可以出现在其短波端。对不同腔结构的掺镱、掺铒光纤光栅激光器的深入研究证明，谐振腔的各向异性对激光器的激射波长偏移起到决定性的作用，波长最大偏移量主要受限于光纤光栅的反射带宽。通过激光腔内的偏振控制器改变谐振腔的各向异性，可以在光纤光栅的反射带宽内控制激射波长的位置。     

一种不等带宽光学梳状滤波器

提出了一种新型—Michelson—三面镜FabryPerot型50GHz不等带宽光学梳状滤波器设计方案,分析和模拟表明:该器件将一路信道间隔为50GHz的输入信号分离成信道间隔为100GHz的奇偶两路输出信号,其中在3dB处,奇数信道带宽大于30GHz用于10Gb/s传输,偶数信道带宽大于60GHz用于40Gb/s传输对于将来的40Gb/s系统,该器件具有优势.     

基于自适应预测滤波理论的模数转换器设计方法

基于自适应差分量化理论，提出了在不增加转换位数的情况下提高模数转换器(ADC)动态范围的一种设计方法。该方法通过量化输入与预测的差值来获得预测增益，从而扩大ADC的动态范围；通过差分量化值与预测值相加得到输出信号，并将该分别采用LMS和RLS算法进行处理．得到输入信号的预测值．计算机模拟结果证实，上述两种算法均能使模数转换器的动态范围提高约25dB．比较而言，RLS算法收敛速度更快，收敛性更好，但计算量较大．     

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。     

Single to 16-Channel Wavelength Conversion at 10 Gb/s Based on Cross-Gain Modulation of ASE Spectrum in SOA

A simple scheme for single to multi-channel wavelength conversion based on cross-gain modulation of amplified spontaneous emission (ASE) spectrum in semiconductor optical amplifier (SOA) is described. Single to 16-channel wavelength conversion at 10 Gb/s is first demonstrated without any additional probe lights, the modulation information carried by input signal could be converted into arbitrary many channels if only the demultiplexer with enough channels is exploited. Output performance and pattern effects are investigated experimentally.     

Multimode optical fiber demultiplexer-star coupler using a single gradient-index-rod lens and a multi-facet grating

An optical fiber multi-function device consisting of a single gradient-index-rod lens and a multi-facet blazed reflection grating is proposed to simultaneously realize functions of wavelength demultiplexing and optical signal distribution in a multimode optical fiber transmission system. We analyzed the demultiplexing characteristics and the tolerance of optical components using the ray trace method. This device can realize not only low loss optical signal distribution but also offers improved demultiplexing characteristics in comparison with the previously proposed demultiplexer-multiposition switch. The following characteristics are expected from the design using commercially available optical components: a working band of 0.64–0.88 μm, channel separation of 34–36 nm, 3 dB bandwidth of 27–28 nm, channel cross-talk of less than - 40 dB and minimum excess insertion loss of 0.9–2.1 dB.     

全固态多波长飞秒脉冲激光系统

利用棱镜对引进频谱空间啁啾来补偿飞秒脉冲激光二次谐波产生中的相位失配,提高了倍频效率建立了一套全固态、多波长(1065nm, 532nm,823.1nm, 402nm)飞秒脉冲激光系统自制的Nd:YVO4激光器输出532nm绿光激光,最高平均功率可达5.6W当用2.5W绿光激光泵浦时,从自制的钛宝石激光器及经BBO倍频可分别输出中心波长为823.1nm和402nm,平均功率300mW和73mW,谱宽32.3nm和5.1nm,脉宽22fs和33.3fs、重复率108MHz的近红外和蓝光激光整个系统具有结构紧凑、倍频效率高、运行稳定的特点.