两维声光Q开关

报道了一种实用高效的两维声光Ｑ开关，描述了两维声光Ｑ开关的基本原理，详细推导出正常布喇格衍射的两维声光Ｑ开关衍射效率和衍射损耗的表达式，分析了两维布喇格衍射和一维布喇格衍射之间的关系，并给出了在驱动功率４０Ｗ，光束直径５ｍｍ，光波长１．０６μｍ时衍射损耗达５０％的实验结果。     

声表面波陀螺效应声光检测技术研究

简要介绍声表面波(SAW)陀螺效应和布喇格声光互作用现象,提出了检测SAW陀螺效应的方法。该方法的核心是通过声光布喇格作用,把SAW陀螺效应引起的声速变化信息寄载到布喇格衍射光中,通过检测布喇格衍射角度推算出固体介质的旋转角速度。论述了SAW陀螺效应检测原理,初步设计了检测系统,推导了SAW陀螺效应检测系统的测量公式。     

多频声光布喇格衍射

多个独立的声波同时作用在声光器件中,入射激光照射到声场,当满足布喇格入射条件时,声光器件输出多个衍射光束。但是,多个衍射光束不是完全独立的。当多个频率的声波同时出现时,除了根据布喇格定律出现相应的光束外,还存在各光束之间的互调制效应和交叉调制效应;当多于一个频率的信号加于声光调制器时,将分别耗费源束的光能,并使衍射光束受到其它声光栅的多次衍射,而使该束衍射光效率降低。加入的频率数目越多,对于一束一级衍射光的衍射     

多通道声光布喇格池

本文报告多通道声光布喇格池的设计和制备工艺。分析了交叉干扰的产生机理以及降低其干扰的方法．３２通道器件衍射效率达到４００％，系统的通道间隔离度为２４ｄＢ。     

双声光二维Q开关提高连续Nd:YAG激光关断损耗研究

分析了单声光器件、超声场相互平行和相互正交的两声光Q开关器件衍射损耗,给出正常布喇格衍射的超声场相互平行和相互正交的双声光Q开关器件衍射效率的表达式.采用功率分配器保证两声光Q开关的同步和有效功率驱动.Nd∶YAG激光器的实验结果表明,超声场相互平行双声光Q开关的关断损耗比单声光器件提高了1倍多,而超声场相互正交双声光Q开关的关断损耗比单声光器件提高了2倍多,能够有效的关断大功率固体连续激光.     

基于声光效应的激光束偏转控制方法研究

给出了基于USB总线的声光效应系统框图,介绍了声光偏转和调制的原理,通过超声波频率的改变来控制激光光束的方向.在布喇格衍射下,测量声光偏转量,计算超声波声速.实验证明,通过改变超声频率可实现对激光光束方向的控制.利用声光效应制成的声光器件在实际中有着广泛应用.     

ZnO单晶薄膜高频声光布喇格偏转器

本文叙述用ZnO膜制作声光布喇格偏转器。单晶ZnO膜是用RF磁控溅射法生长在兰宝石基片上,测得了对波长为0.63μm制导激光束的衰减约1.2dB/cm和对SAW一阶高次模(1st)的机电耦合系数k~2约4％。利用ZnO膜的这些优良特性实现了频率为1GHz SAW输入功率为1W的、衍射效率为50％的声光布喇格偏转器。适当设计叉指换能器(IDT)就能够使这种声光偏转器实现宽带声光布喇格偏转器。     

布喇格声光衍射在激光探测中的应用

本文叙述了布喇格声光衍射原理,结合实验结果说明该原理在激光主动探测中的成功应用。     

第二讲 声光布喇格衍射

上一讲已经指出,布喇格衍射是声光互作用的一种主要表现形式,由于它具有高达100％的衍射效率,故用途极为广泛,并因此受到青睐,对其研究的深度、广度也自然强于喇曼-奈斯型。出于此因,我们在这一讲里将重点、深入讲述布喇格衍射效应,在普遍的耦合波方程的基础上导出一种更为简明和实际的分析布喇格衍射的方法——耦合模方程,或称振幅方程的分析方法。进而对大角度、小角度的布喇格衍射、发散光波的衍射等作较为深入的分析。     

固体声光锁模器

本文简要介绍声光锁模器的基本原理和设计重点,研制了喇曼-奈斯型和布喇格型两种器件,在激光锁模中获得了良好的使用。     

Remotely programmable routing device with optical clock division

We demonstrate the first time-division routing (demultiplexing) device that operates entirely in the optical domain. The device is remotely programmable: the data channels that are present during the device start-up are routed to one of the two output ports, the remaining channels are routed to the other port     

双通道衍射计算成像光谱仪系统

常规衍射光谱成像系统采用单通道方案,主要针对简单图形目标或光谱特征已知的气体目标进行模拟仿真和光谱成像实验。而当目标为自然场景等复杂景物时,成像系统的光谱解算效果和精度难以保证。针对复杂景物成像,设计了一套双通道可见近红外衍射计算成像光谱仪系统,在常规单通道衍射成像光谱仪系统的基础上,增加一路全色相机成像,可以为衍射成像通道提供复杂景物的全色信息和先验知识。将两个通道的数据进行联合处理,提升最终的光谱数据反演效果和反演精度。介绍了系统组成和基本原理,分析了系统性能,利用仿真程序模拟了系统成像过程。在实验室搭建了可见近红外衍射计算成像光谱原理验证装置。对实验得到的450~800 nm的可见近红外混叠光谱数据进行光谱复原。利用海洋光学光谱仪测试色板的光谱曲线作为标准谱线,与复原得到的光谱数据进行对比,反演的光谱数据平均精度优于90%。通过衍射计算成像原理分析、模拟仿真和原理实验,验证了双通道衍射计算成像系统原理的正确性,能够反演得到精度优于90%的复杂景物光谱数据,提升了衍射成像光谱系统应用潜力和应用价值。     

Performance Enhancement in Double-Gated Poly-Si Nanowire Transistors With Reduced Nanowire Channel Thickness

A new method is proposed and successfully demonstrated for the fabrication of polycrystalline silicon (poly-Si) nanowire (NW) transistors with rectangular-shaped NW channels and two independent gates. The two independently controllable gates allow higher flexibility in device operation and provide a unique insight into the conduction mechanism of the NW device. Our results indicate that dramatic performance enhancement is feasible when the thickness of the NW channel is sufficiently thin, and the two conduction channels in the NW structure are operating simultaneously.      

基于可调谐变频芯片的有线宽带接入技术方案

本文提出一种基于可调谐变频芯片的有线网络宽带接入技术方案,它由具备多信道同时通信能力的局端设备和工作频率可调谐的用户端设备组成,应用到有线电视同轴电缆网络的两侧,从而实现一种全新的有线网络双向宽带数据通信方式。这种技术首次采用的可调谐变频芯片,能充分挖掘有线网络的频谱优势,灵活利用同轴电缆上的闲置频谱,具有信道可扩展、频点可调谐、系统带宽可扩展等优点。本文给出可调谐变频通信的概念,介绍可调谐变频芯片及其系统应用。     

Performance of Waveband MUX/DEMUX Using Concatenated AWGs

Recently, we proposed a new waveband multi/demultiplexer that uses two concatenated arrayed-waveguide gratings. We fabricate the device using silica planar lightwave circuit technology and experimentally confirm its feasibility. The device was designed to accommodate 40 100-GHz-spaced C-band channels on the ITU-T grid and six input fibers simultaneously, that is, one chip can support 240 channels.     

Monolithically integrated multiwavelength grating cavity laser

A multiwavelength grating cavity laser is reported using a novel design for a multichannel light source based on an etched diffraction grating. Following the design, the compact eight-channel device capable of fine-tuning has been realized by monolithically integrating semiconductor optical amplifiers, various passive waveguides, and deeply etched grating, providing high butt-coupling efficiency, and low waveguide losses. As a result, the sidemode suppression ratio in excess of 45 dB over all channels was achieved.     

Differential Polarization Delay in Coupled-Resonator Optical Waveguides

An integrated device capable of dynamically controlling the differential delay between two orthogonally polarized data channels is presented. The polarization-selective delay is induced by exploiting waveguide birefringence in a ring-resonator coupled resonator optical waveguide. A prototype realized in silicon-oxynitride technology is employed to manage the differential delay between two polarization-division-multiplexed channels modulated up to 10 Gb/s over several bit-slots. Reconfiguration is achieved by thermo-optic effect with 1-ps delay accuracy. Back-to-back and propagated bit-error-rate measurements show minor deterioration of the signal with negligible polarization crosstalk.     

Digitally tunable channel dropping filter/equalizer based onwaveguide grating router and optical amplifier integration

We demonstrate a novel and powerful device that permits individual and simultaneous control of all the wavelength channels in a WDM system. The device is based on the monolithic integration of two identical waveguide grating routers with semiconductor optical amplifiers. By biasing appropriately the individual amplifier, each WDM channel can be amplified, detected or modulated. The device exhibits a channel bandwidth of 60 GHz, a channel spacing of 195 GHz and a crosstalk of -19 dB     

Large N x N waveguide grating routers

We show how the grating diffraction properties of a N×N waveguide grating router (WGR) can limit the size of N when the device operates with a unique set of N wavelengths as a strict-sense nonblocking N×N cross connect. We motivate why for large N, the N optical channels should be chosen equally spaced in wavelength and not in frequency. Two different approaches to increase N are presented. We report on results obtained in a 40×40 and a 80×80 WGR     

Two-dimensional grating unit cell demultiplexer for thin-film optical waveguides

An optical wavelength demultiplexer has been constructed on a planar waveguide using a pair of crossed gratings which have the same spatial frequency. The device is tunable and can separate spatially two channels 1.6 nm apart at 594.8 nm. Channel crosstalk is very low and the device can readily be cascaded.