光纤耦合声光Ti:LiNbO3波导器件的研究

波导型声光调制器作为高功率全光纤调Q激光器中的调制器件,光纤与器件对接耦合损耗大是影响其性能的主要因素。通过分析波导端面的Ti条半宽度与光波导模场分布的关系,计算出Ti∶LiNbO3锥形光波导与光纤耦合损耗最小时对应的最佳Ti条半宽度。分析得到Ti∶LiNbO3波导端面的Ti条半宽度对耦合损耗的影响,以及光波导的不同切型对最佳Ti条半宽度的影响。     

衍射器件实现单模光纤与光波导低损耗耦合

提出了一种集成化衍射光学模式转换器。利用衍射光学器件(DOE)实现模式转换，消除模式失配，实现单模光纤(SMF)与光波导的低损耗耦合。DOE的相位分布由数值迭代相位恢复算法优化得到。在迭代算法中引入一种新的混和远场约束，达到很高的模式转换质量。此方案适用于任何波导结构。分别针对不同尺寸及不同折射率对比度的方形波导、薄膜波导和脊形波导进行了设计，耦合损耗均降至0.12dB以下。     

Ti:LiNbO_3波导与光纤耦合综述

本文从Ti:LiNbO_3波导与光纤的模场分布、数值孔径以及几何尺寸三要素论述Ti:LiNbO_3波导与光纤的耦合问题,并扼要介绍几种适合工程应用的高效耦合方法.     

平面光波导与光纤的低损耗耦合

文章提出一种新型的波导结构,该结构通过改变波导芯在宽度和长度方向的截面形状和大小,借此来改变波导中光束的模场分布,有效地降低了波导与光纤间的耦合损耗,提高了产品性能。此外,该波导结构生产制造相对简单,易于大规模生产。     

光波导-单模光纤的直接耦合

实现光波导－单模光纤的耦合是各种集成光学器件从实验室走向实用化的关键，耦合效率的高低直接影响到各种集成光学产品的性能。本文在分析影响耦合效率的主要因素的基础上，对现有的几种光波导－光纤耦合方式作了进上步的分析和比较。     

纳米锥SiGe-SOI光波导与光纤的耦合分析

Based on a submicrometer-sized SiGe-SOI waveguide, the coupling loss mechanism is analyzed between the submicrometer-sized SiGe-SOI waveguide and the fiber. The main sources of coupling loss are analyzed, and the mismatch loss of the mode field is the mainly lost during connection between the submicrometer-sized waveguide and the fiber. In order to reduce the mismatch loss of the mode field, the structure ofa nanotaper SiGeSOI waveguide with a nanometer-sized tip is adopted. By reducing the waveguide dimensions to increase the mode field size, coupling loss could be reduced between the waveguide and the fiber. Different mode field dimensions ofnanotaper SiGe-SOI waveguides and fiber are quantitatively analyzed, and the quantitative relationship between nanotaper SiGe-SOI waveguide dimensions and mode field dimensions are obtained. Finally, nanotaper SiGe-SOI waveguides are made, and the test and analysis have been done. The final experimental results accord well with the theoretical analysis. When the waveguide width is 0.5 μm, the minimum coupling loss of the SiGe-SOI waveguide is 0.56 dB/facet, and also the correctness of the design method and theoretical analysis are verified.     

光纤与波导的对接耦合

本文报道了利用Ｓｉ单晶各向异性的特点，在两块Ｓｉ单晶片上，择优蚀刻出排列形状不同的Ｖ形Ｓｉ槽，通过嵌入Ｖ形槽中的光纤，将间距为６０μｍ的１０个信号耦合到探测器的间距为１０００μｍ的１０个接收面上。     

光纤与波导直接对中耦合的实验研究

本文叙述了光纤与波导耦合的理论,着重介绍光纤与波导直接对中耦合实验,实验中测得光纤—波导—光纤耦合损耗为2.5dB。文中对存在的问题也进行了讨论。     

LiNbO3光波导器件及其在光纤通信中的应用状态

ＬｉＮｂＯ３光波导器件不受光信号带宽限制，易实现系统的高效率和高速化，是构成现化超高速、大容量和长距离光纤通信干线系统和光交换系统极具魅力的关键器件。本文着重介绍ＬｉＮｂＯ３光波导及其器件原理、结构、性能与制作技术。以及在光通信领域中的应用。     

Design considerations for acousto-optic devices

The design and fabrication of wide-band bulk acousto-optic modulators (temporal modulation) and beam deflectors (spatial modulation) are described. Optimized device parameters can be obtained systematically for given specifications of the desired modulation bandwidth, throughput efficiency and number of resolvable elements. As the device operating frequency goes beyond a few hundred megahertz, the acoustic transducer response becomes sensitive to the intermediate metal layers between the piezoelectric transducer and the acoustooptic interaction medium. Transducer bandwidth and impedance matching can be optimized using computer modeling programs. Criteria for material selection based on performance requirements and propagation loss are presented. Practical considerations for the fabrication of high performance devices and specific device parameters are discussed.     

Highly-efficient broadband acoustic transducer for all-fibre acousto-optic devices

An acoustic transducer for excitation of acoustic waves to an optical fibre with high efficiency and smooth frequency response is demonstrated. Reducing the size of the transducer to an order of the acoustic wavelength has resulted in low power consumption and smaller efficiency variations during wavelength tuning.     

Fiber attachment for guided wave devices

Reviews the status of fiber attachment to guided wave devices. Current methods for achieving low fiber-waveguide-fiber insertion loss are discussed and techniques for aligning and permanently attaching fibers are described     

激光外差干涉中声光器件非互易特性研究

针对声光器件存在的非互易现象导致光强衰减影响衍射效率并降低激光外差干涉效率的问题,进行了一种基于声光驱动100MHz时声光器件非互易效应对激光外差干涉影响的研究。以光束衍射实验为主体,结合光阑、TeOa晶体对声光器件非互易值进行测量,利用光功率计获得测量过程中的器件非互易数值,在不同驱动频率下分析衍射效率分布情况;并利...     

Large jobs for little devices [microelectromechanical systems]

Microelectromechanical systems (MEMS) may become key components of radio frequency devices, particularly in the mobile marketplace. In filters, they may lower radio size and power consumption while increasing sensitivity. In switches, they could herald the construction of cheaper, electronically steerable antennas for radar and communications applications. MEMS are electromechanical devices with tiny moving parts. They can be built using IC-compatible materials, such as polysilicon, allowing their integration on a silicon chip, side-by-side with semiconductor circuits. Experimental filters are now reaching hundreds of megahertz, and operation up in the gigahertz ranges needed for most wireless and some satellite communications should be feasible. Their ability to kill several birds with one stone is making them very attractive to researchers and developers     

水面声光耦合光纤水听器的抗波浪解调方法

为了减弱基于水面声光耦合的光纤水听器水面波动对解调信号造成的幅度衰落,采用了利用检测信号臂光强度信息补偿解调信号幅度的方法。从理论上推导了该方法修正解调信号的过程,并对该过程进行了数值仿真,同时实际搭建光纤水听器探测系统,利用/2相位解调法对水面恒定振动信号进行了实验验证。结果表明,相比原始解调信号,修正后的信号幅度基本稳定,幅度值整体提高5dB,解调信号失真度减小,相位噪声得到抑制,信噪比得到提高,可辨认信号时间长度扩展为原来的3.5倍。该方案能有效克服由水面波动引起的解调信号衰落现象,信号质量得到优化,系统抗波浪解调能力得到提高。