2.5GHz非归零码光脉冲的波长变换实验

报道了采用国产器件进行了中心波长为１．５５μｍ，重复频率为２．５ＧＨｚ的非归零码光脉冲基于半导体放大器的交叉增益调制的波长变换实验，波长变换距离２．７ｎｍ。     

外腔激光器实现波长变换的理论及实验

理论上从半导体激光器的速率方程出发,利用其增益饱和效应,提出了光纤光栅外腔半导体激光器实现波长变换的理论模型。利用此模型对入射波为高斯波时的波长变换进行了数值模拟。实验实测了光纤光栅外腔半导体激光器的波长变换前后的谱线,得到带宽 0.1nm,边模抑制比为37.9dB 的激光谱线,并且利用此波长的外腔激光器得到了波长转换间隔为 8nm 的激光谱线。理论分析和实验结果证明,光纤光栅外腔半导体激光器在实现波长变换方面具有很好的线性响应特性。     

掺铈硅酸镥(Lu2SiO5:Ce)晶体的生长与闪烁性能

用Czochralsky方法和铱坩埚感应加热技术生长出了尺寸为φ35mm×40mm的掺铈硅酸镥(LSO:Ce)闪烁晶体.透射光谱表明,由于铈离子的掺入,使晶体的吸收边由纯LSO晶体的195nm红移至380nm.LSO:Ce晶体的紫外激发波长按强度递减的顺序依次为380、333、319和216nm,其光发射为带状谱,波长覆盖范围从390nm至560nm.X射线激发的发射谱具有典型的双峰特征,峰值波长为393nm和.426nm.这些特征与Ce3+离子基态能级4f1因自旋-轨道耦合而产生的两个分裂能级和Ce+离子在LSO晶体中占据两个不同的结晶学格位有关.     

波长路由在并行计算机光互连中的应用

提出了一种波长路由并行光互连技术，其路由直接在源端用目标地址选择波长来建立，各波长有独立传输路径并采用光通道复用，路由变换节点为全光结构，光信号在变换节点处无转发延迟。此技术可应用于并行计算机互连网络和分布式高性能计算机群的互连网络。     

基于X光光刻的亚波长光栅

描述了一种新的亚波长光栅的微细加工技术,即X光光刻得到相应的亚微米级的线宽图形,再利用显影技术获得了高深宽比的立体亚波长光栅．用此纳米加工技术获得了栅距为500nm、250nm、150nm,光栅高度为1900nm的特殊纳米光栅模具,开发了纳米无反射结构,并研制成功了亚波长光栅．该亚微米线宽微细加工技术可用于布拉格光栅、DVD读写头、无反射表面等需要亚微米结构的器件中．     

掺铈硅酸镥(Lu2SiO5:Ce)晶体的生长与闪烁性能

用Czochralsky方法和铱坩埚感应加热技术生长出了尺寸为φ35mm×40mm的掺铈硅酸镥(LSO:Ce)闪烁晶体.透射光谱表明,由于铈离子的掺入,使晶体的吸收边由纯LSO晶体的195nm红移至380nm.LSO:Ce晶体的紫外激发波长按强度递减的顺序依次为380、333、319和216nm,其光发射为带状谱,波长覆盖范围从390nm至560nm.X射线激发的发射谱具有典型的双峰特征,峰值波长为393nm和.426nm.这些特征与Ce³⁺离子基态能级⁴f₁因自旋-轨道耦合而产生的两个分裂能级和Ce⁺离子在LSO晶体中占据两个不同的结晶学格位有关.     

立方相NaYF_4∶Ce~(3+)材料的合成及上转换发光性能

以氟化钠、硝酸钇、硝酸铈为原料,采用水热法和共沉淀法合成棒状NaYF4∶Ce3+材料,利用XRD、SEM、红外光谱、荧光光谱分析仪对其结构和发光性能进行表征。结果表明,制备样品均为立方相结构,表面含有以化学吸附方式存在的EDTA分子。经水热法制备样品的上转换发射发射出波长在404.5nm和436nm处的蓝光,以及波长在520.5nm和539nm处的绿光。     

一种用于通信C波段的光轨节点无源集成芯片

光轨是一种新型光通信网络结构,具有交换粒度小、带宽利用率高等优点。本文提出一种应用于通信C波段的新型光轨节点无源集成芯片,支撑1 545 nm、1 550 nm和1 555 nm三个C波段波长的通信。该新型光轨节点无源集成芯片是一种基于SOI纳米波导材料的片上微器件系统,核心器件由基于微环谐振器的解复用器和基于马赫-泽德尔干涉仪的环加强型热光光开关构成。通过理论计算和软件仿真,分别分析了解复用器和光开关的光学和通信性能,结果显示微环解复用器3个波长信道的串扰分别为22.5 dB、16.9 dB和16.3 dB;光开关的消光比分别为16.6 dB、19.7 dB和21.5 dB;插入损耗分别为0.86 dB、0.85 dB和0.68 dB,功耗约为51 mW。     

基于分数傅里叶域信号处理的迈克尔逊干涉法测量波长北大核心CSCD

建立了迈克尔逊干涉法测量波长所得条纹图的数学模型,揭示了其线性调频信号(chirp信号)特性,提出了基于分数傅里叶变换信号处理方法对迈克尔逊干涉条纹进行处理,实现了激光波长测量。实验结果表明:该测量方法具有可行性,对于波长范围为400~635 nm的激光,波长测量的平均相对误差约为0.39%。在干涉条纹图被高斯白噪声污损情况下,波长测量的平均相对误差仍然小于1%。     

紫外-可见光检测器波长准确度的几种检测方法

通常意义上的可变波长紫外-可见光检测器就是装有流通池的紫外-可见分光光度计。为避免波长误差对仪器测量准确度和灵敏度的影响，现有的紫外-可见光检测器大多性能完备，具有完善的自动波长校准功能。现代液相色谱仪一般校正(0-656)nm的波长。首先使用零级     

O-band to C-band wavelength converter by using four-wave mixing effect in 1310 nm SOA

In this paper we provide a detailed account of an ultra-wideband wavelength converter that shifts from 1310 to 1550?nm using a 1310?nm semiconductor optical amplifier as the nonlinear medium. The experimental approach uses an arrayed waveguide grating (AWG) as a method to slice the broadband output ASE of the 1310?nm SOA into multiple outputs at this O-band. A four-wave mixing technique is used to generate the wavelength conversion, whereby two wavelengths at 1310?nm are used and interact with the 1550?nm continuous wave output from a bismuth-based erbium-doped optical amplifier. In this demonstration, the interacting wavelengths are 1316.75, 1317.47 and 1542.21?nm. The downward conversion wavelengths are 1542.93 and 1541.49?nm, with a converted wavelength spacing of 224?nm.     

Optimized design of fluorinated polyimide based interleaver

Statistical optimization method for the design of a fluorinated polyimide wavelength division element for optical communication is proposed. The opitimized device is an interleaver element suitable for dividing over 40 wavelengths in the 1550 nm band. Optimization considers the inherent polarization dependence of fluorinated polyimide based on measurements of the dispersion characteristics and birefringence of fluorinated polyimide film. A 40-wavelength device is designed by use of the proposed technique for a working wavelength of 1550 nm and a wavelength interval of 0.8 nm. The device exhibited a 1-dB passband of 0.5 nm and a 3-dB passband of 0.8 nm, and output wavelength fluctuation due to polarization effects of less than 0.08 nm.     

用差频腔产生覆盖633nm光谱的飞秒激光频率梳

飞秒激光频率梳被认为是连接光频和无线电频率的一个超精密齿轮,比较了自参考法锁相稳频飞秒激光频率梳和差频法单块结构飞秒激光频率梳的特点,前者光谱范围宽,但稳定性较差;后者稳定性较好,但光谱范围较窄。在差频腔单块结构飞秒激光频率梳的基础上,通过使用腔外压缩色散补偿方式压缩激光脉冲宽度,然后重新注入光子晶体光纤进行光谱扩展,获得了覆盖633nm波长的更宽的光谱范围,为633nm波长激光频率测量创造了条件。     

A novel optical device with wide-bandwidth wavelength conversionand an optical sampling experiment at 200 Gbit/s

This paper reports the characteristics of our proposed prototype optical parametric diffuser (OPD). An OPD is based on the theory of four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). However, to improve the conversion bandwidth and FWM efficiency, the gain bandwidth is spread and the gain peak wavelengths are set to a wavelength near the FWM light on the short-wavelength side by combining different MQW active layers. We measured the optical gain characteristics; the fiber-to fiber gain was 16.1 dB and the gain bandwidth over 8 dB was 117 nm when driven at 200 mA dc, and 190 nm when driven by an 800 mA pulse current. In a wavelength-conversion experiment, a high conversion efficiency of ⩾-20 dB was obtained across a detuning wavelength bandwidth of 43 nm. A clear waveform was obtained in an optical sampling experiment to measure 200 Gbit/s optical data sequences     

Color separation of high-density dielectric rectangular grating in the Fresnel diffraction region

A high-density dielectric rectangular grating is designed for color separation in a Fresnel diffraction field. The Fresnel field distribution is analyzed and the optimization conditions for color separation are given. The process of the modes propagating and energy exchanging with the diffraction orders are expressed by modal method. The color separation for different polarizations can be realized. The energy efficiency is 96.3% at the 633 nm wavelength and 86.9% at the 488 mm wavelength for both TE polarizations, while the energy efficiency is theoretically 96.3% at the 633 nm wavelength for TE polarization and 90.6% at the 488 nm wavelength for TM polarization. The field distributions are scanned by the near-field scanning optical microscopy, and the efficiency is 71.2% for the 633 nm wavelength and 67.3% for the 488 nm wavelength for both TE polarizations experimentally.     

Optical breakdown on a target surface under a simultaneous laser pulse action at the wavelength of 248 and 532 nm

It is found that under, a double-pulse optical breakdown, the energy of the main pulse with a wavelength of 532 nm is diminished by up to two times, provided that the preionization of the target surface is performed by a laser pulse with a wavelength of 248 nm. It is shown that the pulse of a shorter wavelength can act as the managing one to specify the optical-breakdown onset and coordinates.     

Optical interleavers based on two-dimensional photonic crystals

An ultrasmall device size optical interleaver based on directional coupler waveguides in two-dimensional photonic crystals (PCs) is proposed. The numerical results show that the proposed PCs waveguide structure could really function as an interleaver with the central wavelength 1550 nm and the channel spacing 0.8 nm (frequency spacing of 100 GHz) of the dense wavelength division multiplexing (DWDM) specification. It can be widely used as the wavelength selective element for multiplexer-demultiplexer to lower or raise channel densities in DWDM optical fiber communication systems.     

Far-field optical superlens

Far-field optical lens resolution is fundamentally limited by diffraction, which typically is about half of the wavelength. This is due to the evanescent waves carrying small scale information from an object that fades away in the far field. A recently proposed superlens theory offers a new approach by surface excitation at the negative index medium. We introduce a far-field optical superlens (FSL) that is capable of imaging beyond the diffraction limit. The FSL significantly enhances the evanescent waves of an object and converts them into propagating waves that are measured in the far field. We show that a FSL can image a subwavelength object consisting of two 50 nm wide lines separated by 70 nm working at 377 nm wavelength. The optical FSL promises new potential for nanoscale imaging and lithography.     

High-accuracy wavelength-change measurement system based on a Wollaston interferometer, incorporating a self-referencing scheme

A novel wavelength-difference measurement scheme with a Wollaston prism is presented. By using a suitable reference wavelength, a small variation in the signal wavelength can be converted into a relatively larger change in the modulated wavelength, as a result of the so-called fringe beating effect, resulting in enhanced measurement sensitivity by use of autocorrelation and Gaussian filtering techniques. From the results of a simulation carried out, we observed a wavelength variation of 0.01 nm over 15 nm or 0.1 nm over 60 nm for a typical pair of laser diodes with wavelengths of 785 and 810 nm, and wavelength variations of 0.5 nm over 40 nm or 1 nm over 110 nm for 671-and 785-nm wavelengths. These results were partially verified by the experimental results obtained for which a resolution of 0.01 nm over a range of 2.5 nm for the first pair and 0.5 nm over 4 nm for the second pair of laser diodes was seen. The results have applications to the determination of wavelength variations in a wavelength-division multiplexing system or measurement of the wavelength changes induced in a range of optical sensors.     

Dynamic O-band to C-band wideband wavelength converter for integrated VCSEL-based optical interconnects

ABSTRACT

Real-time wavelength conversion and traffic routing at key network nodes is a fundamental requirement for current optical interconnects. This work experimentally demonstrates a broadband wavelength conversion from O-band to C-band employing commercially available, power efficient VCSELs. A 1310?nm VCSEL is directly modulated with 8.5 Gbps data and transmitted over 22?km G. 652 fibre with a 0.53 dB penalty. The received data is used to run a 1550?nm VCSEL located at the network integration node, achieving the first reported wavelength conversion from O-to-C-band. VCSEL wavelength tuneability with changing bias current functionality is further exploited to route the converted wavelength over 400?GHz spectra range for integration into wavelength flexible networks. The newly converted wavelength is transmitted over 24.7?km of G. 655 fibre, incurring a maximum penalty of 1.86?dB. Results from this work proves an enabling development technology for wavelength converters for transparent contention resolution in current and future optical Interconnects.