外腔半导体激光器阵列波长稳定的实验研究

自由运行的半导体激光器列阵输出激光谱线较宽、中心波长易漂移.为此,本文采用体全息光栅(VBG)构成外腔半导体激光器阵列(EcLD)系统,利用体光栅能够稳定波长、压窄线宽的特点,从而克服上述缺点.实验表明:采用了VBG外腔反馈后,在最好的情况下,LDA的输出光谱宽度从自由运行时的2.3 nm压窄到了O.96 nm;在测试的环境温度变化范围内(14～3l℃),LDA的峰值波长稳定在体光栅布拉格波长808 nm处,输出光的线宽维持在1.14 nm之下;并且,在测试的偏置电流变化范围内(7-13A)峰值波长和谱宽无明显变化.     

基于光纤光栅外腔半导体激光器的2.5Gb/s波长转换实验

首次用光纤光纤光栅外腔半导体激光器的方法进行了2．5Gb/s的波长转换实验,将波长向上转换了5nm,得到了较清晰的眼图。该激光器采用标准的DIP－14低成本封装,该波长转换方法具有输出波长稳定,低啁啾的特点。     

光纤光栅半导体激光器激射波长与Bragg波长的偏离

利用包含光纤布拉格光栅(FBG)反射率分布的光纤光栅外腔半导体激光器(FGSL)的理 论模型,对FGSL 的激射波长进行了研究。结果表明激射波长并不一定在FBG布拉格反射波长处;布拉格反射波长相对于激射波长的偏移量与FBG的反射率分布、半导体增益介质的增益谱分布及增益峰值波长有关;激射波长可大于或小于布拉格反射波长。     

外腔激光器光子寿命对波长转换特性的影响

作为自动交换光网络中的核心器件,全光波长转换器发挥着重要作用。本文根据光纤光栅外腔半导体激光器(FBG-ECL)实现波长转换的理论模型,重点研究光子寿命对波长转换器调制特性的影响;利用速率方程,数值求解了不同光子寿命下波长转换特性;通过自行搭建的基于FBG-ECL的实验平台进行了实验分析,发现理论分析和实验数据是吻合的。     

光纤Bragg光栅的特性及应用研究

介绍了光纤光栅研制及其应用研究的情况。研究包括：光纤光栅的基本特性,光纤光栅外腔半导体单频和锁模激光器、光纤光栅稳频光纤环形激光器和主动锁模光纤激光器、基于光纤光栅的波长转换器和基于啾啁光纤光栅的可调谐激光器等。     

基于光纤光栅技术的新型光子器件及其在动态可配置波分复用光网络中的应用

报道了光纤光栅外腔激光器、基于可调谐光纤光栅的动态可配置分插复用器(OADM)和全光波长转换器等在全光通信网中有应用潜力的新型光子学器件的实验结果，演示了这些器件的功能，基于这些器件建立了4路符合ITU—T波长标准，间隔为1．6nm的具有动态波长路由、全光波长转换及光信号实时监控功能的密集波分复用光网络演示系统。     

基于光纤布喇格光栅传感器的精密位移测量

首先对光纤布喇格光栅传感的基本原理进行了分析,并给出了光纤光栅位移传感的基本公式.在此基础上,设计制作了一种光纤光栅位移传感器.采用光纤光栅作为传感元件,利用多波长计进行波长检测,对位移量进行了传感测量.实验中,传感器位移检测范围为0.6mm,其传感测量精度为±43nm,测量分辨率为1.5nm.实验结果具有良好的线性度.     

多波长掺镱光纤激光器实验研究

为了产生室温下掺镱光纤激光器稳定的多波长激光振荡,采用两个光纤环镜作为线形腔掺镱光纤激光器的端镜,在其中一个环镜中熔接一段保偏光纤构成梳状滤波器,通过优化掺镱光纤长度和腔损耗,实现了室温下1060nm附近稳定的多波长振荡.实验结果表明,在室温下,掺镱光纤存在比较明显的非均匀加宽效应,从而使得激光器的振荡波长数随泵浦功率的增加而增加.     

宽带光纤拉曼放大器的增益平坦化实验研究

本文采用波长为 1 455nm的大功率光纤拉曼激光器(FRL)作为泵浦源,啁啾布拉格光纤光栅作为增益平坦滤波器,用两种不同的光源组合作为信号源(宽带ASE光源) 波分复用模拟器(WDM-emulator)以及四通道外腔可谐调式激光器(ECL) 滤波器型波分复用器(FWDM))对光纤拉曼放大器的增益平坦化特性进行实验研究,获得了平坦增益带宽为55nm(1 519～1 574nm),平均开关增益大小为15.2dB,增益不平坦度为±0.8dBd的宽带光纤拉曼放大器.通过实验研究表明,该方案为带宽低于60nm的光纤拉曼放大器的增益平坦化设计提供了一种新的选择.     

一种基于EDFA+NDF的全光波长变换

针对目前全光波长变换大多是利用半导体光放大器来实现的现状,本文提出了基于掺饵光纤放大器(EDFA)和非线性色散光纤(NDF)的全光波长变换.该方法利用抽运光和信号光同时输入NDF中时,NDF中产生的四波混频效应(FWM)能有效的产生新的光波,从而实现全光波长变换.文中首先介绍了利用OptiSystem软件成功实现了全光波长变换的仿真,接着在实验室中通过利用掺饵光纤放大器以及G655实现了全光波长变换.获得了最高-16.7dB的变换效率.实验结果表明,无论是理论模拟还是在实验室均获得了清晰明显的波长变换波形.     

Soft X-rays generated by the electron-cyclotron resonance discharge in heavy gases sustained by a high-power microwave beam in a magnetic trap

The soft X-ray line emission from a pulsed electron-cyclotron resonance discharge in argon, maintained by a high-power millimeter-wavelength beam in a magnetic mirror trap, was studied using a multilayer mirror X-ray monochromator. The X-ray spectrum was measured, and the absolute spectral intensity of emission was determined in a 6–17 nm wavelength range. The discharge can be used as an effective source of soft X-rays with an efficiency of the microwave to X-ray power conversion on a level of 10% and a maximum spectral power density of 7.3 kW/nm at a wavelength of 9 nm.     

Multiwavelength picosecond and single wavelength femtosecond pulses emission in a passively mode-locked fiber laser using a semiconductor saturable absorber mirror and a contrast ratio tunable comb filter

We propose and demonstrate a highly flexible fiber laser capable of generating stable multiwavelength picosecond and single wavelength femtosecond pulses by using a semiconductor saturable absorber mirror and a contrast ratio tunable comb filter. In the multiwavelength lasing regime, up to 11-wavelength stable mode-locked pulses in 3 dB bandwidth with a channel spacing of 0.8 nm were obtained. While in the single wavelength with broadband spectrum lasing regime, the fiber laser emitted 576 fs soliton pulse. Through changing the contrast ratio of the comb filter, the conversion between the multiwavelength picosecond and single wavelength femtosecond pulsed operations could be efficiently achieved.     

Generation and optical parametric amplification of picosecond supercontinuum

We have demonstrated the output characteristics of optical parametric amplification (OPA) seeded by a supercontinuum (SC) generated in deionized water excited by 1064 nm. The SC spectrum (from 426 to 943 nm) overlaps well with the tuning range of a 355 nm pumped OPA for both the signal and idler. The tunable range covers from 430 to 2035 nm, with a maximum overall energy conversion efficiency of 32% in the OPA stage. A FWHM bandwidth of 54 nm near the degeneracy point from 658 to 760 nm can be generated by using a collinear OPA. Chirping of the SC pulses is also investigated with the OPA technique. The time delay between the 430 nm component and the 567 nm component of the generated SC due to chirp is measured to be -10.72 ps, increasing almost linearly with the wavelength.     

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.     

熔锥型光纤声光可变衰减器

利用耦合模理论对光纤熔锥声光器件进行了数值模拟，得到了全光纤声光衰减器传输谱和可调谐性。分析了带宽与声波长、耦合长度的关系。数值分析结果表明，声波在光纤熔锥中引起的轴向电介质微扰、耦合长度和工作波长都会对器件的传输谱产生影响，选择合适的设计参数可以制作较为理想的声光衰减器。实验上获得了损耗小于0．2dB，带宽大于200nm，动态范围为20dB的单模光纤熔锥可变衰减器，所得结果与理论分析相符合。这种器件可用于光纤通信及光纤传感。     

Opaline backreflector coating in dye-sensitized solar cell

Photonic crystals are ordered nanostructures that are designed to manipulate the propagation of light. The periodicity of a photonic crystal can be engineered to be highly reflective at selected wavelengths. In this work, a mono-layer and double-layer colloidal photonic crystal film were self-assembled on a glass substrate to be used as backreflectors in a dye-sensitized solar cell (DSSC). The colloidal photonic crystal film consists of different polystyrene monodispersed particles with sizes between 200 nm and 290 nm. Making use of flow controlled vertical deposition (FCVD) method, opaline films of Bragg's reflection wavelength between 450 nm to 750 nm were achieved. These wavelengths were designed to match the absorption spectrum of the Ruthenium-complex dye used in DSSC. An enhancement in incident photon-to-current conversion efficiency (IPCE) of the opaline backreflector DSSC of about 30% at Bragg's peak wavelength has been achieved.     

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.     

High-efficiency dye-sensitized solar cell based on a nitrogen-doped nanostructured titania electrode

A highly efficient dye-sensitized solar cell (DSC) was fabricated using a nanocrystalline nitrogen-doped titania electrode. The properties of the nitrogen-doped titania powder, film, and solar cell were investigated. The substitution of oxygen sites with nitrogen atoms in the titania structure was confirmed by X-ray photoemission spectroscopy (XPS). The UV-vis spectrum of the nitrogen-doped powder and film showed a visible light absorption in the wavelength range from 400 to 535 nm. An enhancement of the incident photon-to-current conversion efficiency (IPCE) in the range of 380-520 nm and 550-750 nm was observed. An 8% overall conversion efficiency has been achieved. The results of the stability test indicated that the solar cell fabricated by the nitrogen-doped titania exhibited great stability.     

Broadband and efficient wavelength conversion in a slot-width switching silicon–organic hybrid waveguide

We propose a slot-width switching (SWS) silicon–organic hybrid waveguide for broadband and efficient wavelength conversion. By switching the slot width of different lengths, the quasi-phase-matching can be obtained. Compared with width-modulated silicon-on-insulator (SOI) waveguide, the non-linear absorption can be ignored in slot waveguide which is filled with p-toluene sulphonate. Consequently, the conversion efficiency at a particular signal wavelength is improved, and the 3-dB conversion bandwidth is also extended. The numerical simulation results indicate that, for a continuous-wave pump at 1550 nm, a conversion bandwidth of 570 nm and a peak conversion efficiency of 11.32 dB can be realized in a 7.5-mm-long SWS waveguide, which is better than that of width-modulated SOI waveguide.     

Digital programmable light spectrum synthesis system using a digital micromirror device

We present a digital programmable light spectrum synthesis system based on a digital micromirror device (DMD) from Texas Instruments. A DMD pattern-scanning calibration method is developed and applied to the synthesis of various infrared C-band (1530-1565 nm) spectral profiles, including a fast programmable tunable light source with a bandwidth of approximately 3.8 nm, a square profile, a sawtooth waveform, and a triangular spectrum profile. The experimental results show that the wavelength resolution of the DMD spectrum synthesis system is approximately 0.076 nm/pixel. The proposed spectrum synthesis system has a number of key advantages, including a rapid and stable performance and multichannel compatibility. The spectrum synthesis system is suitable for various applications, including pulse shaping for coherent control and harmonic generation, a tunable light source, an equalizer for erbium-doped fiber amplifiers, and a wavelength scanner.