激波调制光子晶体频率转换效应的研究

研究了被激波调制的光子晶体对入射光产生的频率转换效应。建立了弹性激波调制一维光子晶体的物理模型;提出了准静态带隙结构的概念,并采用FDTD和平面波展开法计算了其光子带隙;通过数值计算和微扰分析,发现该频率转换是一个量化累积过程,并对该频率转换效应及其量化累积现象提出一种基于光子一声子相互作用和表面衰减模的解释,同时,分析了该频率转换效应的特性。     

激波调制光子晶体频率转换效应的研究

研究了被激波调制的光子晶体对入射光产生的频率转换效应.建立了弹性激波调制一维光子晶体的物理模型:提出了准静态带隙结构的概念,并采用FDTD和平面波展开法计算了其光子带隙;通过数值计算和微扰分析,发现该频率转换是一个量化累积过程,并对该频率转换效应及其量化累积现象提出一种基于光子-声子相互作用和表面衰减模的解释,同时,分析了该频率转换效应的特性.     

任意拓扑结构全光WDM网络中波长转换器配置的遗传算法

波长转换是应用在全光WDM网络中打破波长一致性约束、降低网络阻塞概率的一种有效技术,但限于波长转换器的高昂成本以及其对信号失真度的影响,目前还不可能为网络中的每个节点均配置波长转换器,所以波长转换器需要以最优方案配置在网络中的个别关键节点上,本文提出了一种在任意拓扑结构的网络中,基于遗传算法的波长转换器配置算法,并对该算法在NSFNET网络上进行了计算机仿真,模拟结果显示该算法非常有效.     

基于1550nm的全固态PBG—PCF的设计

设计了一种三角晶格结构的全内反射型光子晶体光纤,并在其包层孔内分别填充折射率为n=1．55～3．35（△n=0．3）的介电材料,使其等效为全固态光子带隙型光子晶体光纤,利用全矢量平面波展开法对其带隙特性进行分析,发现随着折射率的增加,光子带隙的位置逐渐向长波方向移动,导模也越来越少。设计一种工作波长为1550nm的全固态光子带隙型光子晶体光纤,计算得到其对应的归一化传播常数β=8．2时,导模的宽度大约为100nm。该光纤在光电转换或者电光转换等方面具有潜在的应用价值。     

微机化仪器一组合式A／D转换器的性能分析

本文分析了由微处理器、Ａ／Ｄ转换器及Ｄ／Ａ转换器组成组合式Ａ／Ｄ转换器的原理，介绍了设计方法和相应的设计公式。并剖析了组合式Ａ／Ｄ转换器的转换速率、误差特性等，为设计出高质量的Ａ／Ｄ转换器提供了定性和定量的保证。     

单光子同步探测中的后脉冲特性分析

本文对单光子探测过程中后脉冲特性进行了理论分析,通过实验对后脉冲概率进行了统计测量,研究发现单光子探测器存在两个电子俘获能级,寿命分别为503 ns和33 ns.研究讨论了同步探测单光子对后脉冲的抑制.     

光致变色二芳烯材料的光子型光信息存储

本文合成了八种光致变色二芳烯化合物,研究了它们的光致变色性质,并综述了它们在光子型光信息存储技术中的应用.在光辐照下,这些化合物在溶液和PMMA膜中均具有良好的光致变色特性.使用这些化合物作为光存储介质,成功进行了系列高密度光子型光信息存储实验,包括全息光存储、双光子光存储和多波长光存储.结果表明:二芳烯材料是光子型全息、双光子和多波长光存储技术中可采用的最理想的存储介质之一.     

微机化仪器中组合式A／D转换器的性能分析

本文分析了由微处理器，Ａ／Ｄ转换器及Ｄ／Ａ转换器组成组合式Ａ／Ｄ转换器的原理，介绍了设计方法和相应的设计公式，并剖析了组合式Ａ／Ｄ转换器的转换速率，误差特性等，为设计出高质量的Ａ／Ｄ转换器提供了定性和定量的保证。     

面向太阳光全光谱应用铒掺杂硫卤玻璃上转换发光特性研究

使用熔融淬冷法制备了Er³⁺掺杂Ge-Ga-S-CsBr硫卤玻璃, 研究了其在1550 nm激光激发下的上转换发光特性, 观察到强的波长中心位于525和545 nm绿色发光及弱的中心波长位于660 nm红色发光, 也观察到了中心波长分别位于810和980 nm的红外上转换发光。基于泵探光功率关系和能级寿命测试研究了发光机理, 发现中间态能级寿命的延长是上转换发光效率增强的根本原因。使用全光谱光源测试了Si太阳能效率, 当使用上转换发光层时, 太阳能电池平均效率从7.28%上升至7.32%。结果显示所探索的稀土掺杂硫卤玻璃有望应用于硅太阳能电池效率增强领域。     

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。     

Investigation of optimum wavelength converter based on nonlinear polarisation rotation in a bulk SOA

This work is focused on understanding and optimising the physical mechanisms responsible for wavelength conversion based on cross-polarisation modulation (XPolM) in a bulk semiconductor optical amplifier. A comparison is made between the conversion performance that can be achieved with cross-gain modulation (XGM) and XPolM in co- and counter-propagation configurations. Wavelength independent conversion can be achieved when nonlinear polarisation rotation and XGM effects are balanced in the case of non-inverted wavelength conversion     

利用SOA中的四波混频实现2.5Gb/s信号的波长变换实验

基于SOA中四波混频效应,对中心波长为15474nm,调制速度为25Gb/s的光信号进行波长变换实验,最大波长变换距离达98nm。     

一种新型IP OVER WDM城域网的节点结构

提出了一种基于波分复用（WDM）,分组交换,副载波复用和波长变换技术的新型全光城域网节点结构,网络拓扑采用环形,网络节点采用可调输出固定输入的选波原则以利于数据的多重接入,副载波复用和基于级联半导体光放大器的波长变换,实现了射频副载波路由信息与基带IP数据包的同步复用和IP数据包的透明传输。     

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.     

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     

Picosecond-pulse wavelength conversion based on cascaded second-harmonic generation-difference frequency generation in a periodically poled lithium niobate waveguide

The wavelength conversion of picosecond optical pulses based on the cascaded second-harmonic generation-difference-frequency generation process in a MgO-doped periodically poled lithium niobate waveguide is studied both experimentally and theoretically. In the experiments, the picosecond pulses are generated from a 40 GHz mode-locked fiber laser and two tunable filters, with which the lasing wavelength can be tuned from 1530 to 1570 nm, and the pulse width can be tuned from 2 to 7 ps. New-frequency pulses, i.e., converted pulses, are generated when the picosecond pulse train and a cw wave interact in the waveguide. The conversion characteristics are systematically investigated when the pulsed and cw waves are alternatively taken as the pump at the quasi-phase-matching wavelength of the device. In particular, the conversion dependences on input pulse width, average power, and pump wavelength are examined quantitatively. Based on the temporal and spectral characteristics of wavelength conversion, a comprehensive analysis on conversion efficiency is presented. The simulation results are in good agreement with the measured data.     

Reservation signalling mechanism for reducing blocking probability in optical burst switching networks with limited wavelength conversion capabilities

First, the optical burst switching (OBS) network with limited wavelength conversion capability (LWCC) is decomposed into multiple wavelength continuous segments according to the position of wavelength converters. Based on the decomposed network model, two reservation signalling mechanisms for OBS-LWCC networks, namely wavelength-amend-on-demand (WAoD) and contention-based limited signalling protocol (CLSP), are proposed to reduce the blocking probability in the OBS-LWCC networks. In WAoD, the congested node sends a feedback message to the closest upstream switch with wavelength conversion capability. The notified switch will change the burst wavelength to the one assigned by the congested node to avoid collision in advance. Extensive simulation results indicate that by applying the wavelength reconfiguration method to the core nodes without wavelength conversion capability, the proposed WAoD scheme can improve the blocking performance in the OBS-LWCC networks significantly. Furthermore, CLSP, which combines the burst time-slot reconfiguration with the wavelength reconfiguration of WAoD, always has the lowest burst loss probability when compared with both the conventional and the proposed reservation mechanisms.     

Linear Dichroism Conversion in Quasi‐1D Perovskite Chalcogenide

Anisotropic photonic materials with linear dichroism are crucial components in many sensing, imaging, and communication applications. Such materials play an important role as polarizers, filters, and waveplates in photonic devices and circuits. Conventional crystalline materials with optical anisotropy typically show unidirectional linear dichroism over a broad wavelength range. The linear dichroism conversion phenomenon has not been observed in crystalline materials. The investigation of the unique linear dichroism conversion phenomenon in quasi‐1D hexagonal perovskite chalcogenide BaTiS₃ is reported. This material shows a record level of optical anisotropy within the visible wavelength range. In contrast to conventional anisotropic optical materials, the linear dichroism polarity in BaTiS₃ makes an orthogonal change at an optical wavelength corresponding to the photon energy of 1.78 eV. First‐principles calculations reveal that this anomalous linear dichroism conversion behavior originates from the different selection rules of the parallel energy bands in the BaTiS₃ material. Wavelength‐dependent polarized Raman spectroscopy further confirms this phenomenon. Such a material, with linear dichroism conversion properties, could facilitate the sensing and control of the energy and polarization of light, and lead to novel photonic devices such as polarization‐wavelength selective detectors and lasers for multispectral imaging, sensing, and optical communication applications.     

Concatenation performance of optical packet switches that incorporate wavelength converters based on four-wave mixing in semiconductor optical amplifiers

Four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) has been acknowledged as a useful wavelength conversion technique especially due to its ability to convert sequences of ultra fast pulses but also simultaneously a number of wavelengths. An analysis is used to investigate the concatenation performance of optical packet switch that incorporate wavelength or waveband converters based on FWM in SOAs.     

Flat broadband wavelength conversion based on cascaded second-harmonic generation and difference frequency generation in segmented quasi-phase matched gratings

Bandwidth enhancement and response flattening of wavelength conversion based on single-pass and double-pass cascaded second harmonic generation and difference frequency generation were investigated in segmented quasi-phase matched (QPM) gratings. It is shown that the signal and pump bandwidths are both efficiently widened by increasing the segment number of the QPM grating and optimising the poling period of each segment. The ripple on the matching response is also very small. The conversion bandwidth in a 3-cm-long three-segment waveguide reaches 150–160?nm, which is over the whole conventional band and long-wavelength band. Larger signal bandwidth can be obtained with a little response flatness penalty and conversion efficiency penalty, which can be compensated by increasing the input pump power. Compared with a sinusoidally chirped optical superlattice device, a wavelength converter based on the segmented gratings has higher conversion efficiency, broader bandwidth and better pump-wavelength tolerance, and is easier to fabricate in practice.