Nonlinear optic phase conjugation

An overview of the field of nonlinear optical phase conjugation is given. The basic properties of a phase-conjugate mirror are discussed, and examples of how this technology can be applied to the areas of high-power lasers, optical communication systems, and optical data processing (including neural networks) are presented. It is shown that the massively parallel data processing capabilities inherent in nonlinear optical interactions, coupled with their passive, all-optical nature, make this class of system potentially useful for the next generations of advanced laser systems, remote sensors, and communications systems, as well as optical data processors and network systems architectures     

Multiwavelength performance of an apodized acousto-optic switch

Use of the acousto-optic switch as a wavelength-routing element in WDM networks is described. The need for deep isolation between wavelength channels has resulted in the search for efficient sidelobe suppression techniques such as tapering of the acousto-optic profile by imbedding an optical waveguide in one arm of an acoustic directional coupler. The theory of sidelobe-suppression in the optical transmission function of a SAW-coupler apodized acousto-optic filter is presented. A low-sidelobe SAW-coupler-apodized AO switch was fabricated and used in a 1.5 micron multi-wavelength WDM switching demonstration employing four 4 nm-spaced optical channels. Crosstalk was below -19 dB for single wavelength selection and below -15 dB for arbitrary routing patterns, a dramatic improvement over unapodized AO switches     

一种高速光纤声光调制器

该文介绍了应用于光纤传感系统中的高速光纤声光调制器的设计和应用。分析了影响光纤声光调制器调制速度的因素,介绍了高速光纤声光调制器的设计方法。最后采用氧化碲(TeO_2)晶体和小束腰光纤准直器得到工作波长1 550nm、光脉冲上升时间23.9ns、插入损耗2.9dB、通断消光比53dB的高速光纤声光调制器。     

Theoretical noise performance of coherence-multiplexedinterferometric sensors

If a number of fiber-optic interferometric sensors are arranged so that their outputs are returned to the user via a common optical bus, then some method of distinguishing the returns from different sensors must be used to recover individual signals. One such method involves using light with a short coherence length, so that returns from different sensors will be mutually incoherent. The interferometric signal associated with each sensor can then be recovered via appropriate optical processing. The author considers sensors multiplexed using this technique and calculates their noise performance. It is found that for systems with only a few sensors, the minimum detectable phase is limited by the noise associated with incoherent interference; this can be minimized by using light with as short a coherence length as is practical. The maximum number of sensors that can be multiplexed is limited by optical power loss. A ladder topology is tentatively found to give the best performance     

Themal spray and adhesive bonding of optical fibres to high-temperature compsie materials

Microstructural characteristic were identified for three surface-mounted optical fibre sensors which were thermal spray bonded to high-temperature composite materials. The primary objective was to determine the defect generation mechanisms that occur during thermal cycling and to make processing and testing recommendations that would optimise the sensor performance. A second objective was to identify areas of microstructural research that would have the most significant impact on the development of high-temperature smart materials. The smart material systems of the present study were comprised of (1) silica optical fibre sessors bonded to titanium matrix composites (TMCs) using a nickel-based thermal spray, (2) silica optical fibre sensors bonded to TMCs using ceramic cement and (3) sapphire optical fibre sensors bonded to titanium matrix composites (TMCs) using a nickel-based thermal spray, (2) silica optical fibre sensors bonded to TMCs using ceramic cement and (3) saphire optical fibre sensors bonded to carbon–carbon composites (CCCs) using ceramic cement. The thermal and prior to any thermal stresscycling. In combination with the non-metallic spheroidal inclusions of the titanium matrix, the microcracking provided a mechanism for disbonding the optical fibres with a subsequent loss of sensor performance. A high degree of kporosity in both systems containing ceramic cements significantly reduced the interfacial bonding area. This, combined with the inherent ceramic brittleness, caused disbonding of the optical fibres in the cemented systems.     

集成光学声光光开关的研究

在集成光学声光可调谐滤波器的基础上，研制成一种偏振无关的集成光学波导型声光光开关，由于采用声光作用实现开关功能，使得开关速度可以达到微秒量级。介绍了这种集成光学波导型声光光开关的工作原理及其基本结构，并对它的插入损耗、隔离度、开关速度这三项光开关的重要性能指标进行了具体的理论分析与计算，然后对制作成的集成光学波导型声光光开关的器件样品进行了性能测试，在室内温度为20℃，入射波长为1．523μm时，测得插入损耗为4．8dB，隔离度为22．0dB。对实验与理论的误差进行了具体分析，并提出了进一步提高其性能指标的相关途径。     

Chalcogenide holey fibres

The fabrication of the first non-silica holey or microstructured optical fibre is reported. The chalcogenide glass gallium lanthanum sulphide was used. Applications of such fibres include optical switching, high power-delivery, acousto-optic devices, air-guiding fibres, fibre sensors, mid-IR devices, amongst others. In addition, holey fibre technology provides an improved route towards fabricating singlemode compound glass fibres     

空间积分声光相关系统对高速信号的处理分析

从声光相关检测原理出发，引入相关检测数学模型，通过其对高速信号处理仿真失效的特点，及将入射光束缩束实现对高速信号处理的方法。由于缩束，使得在光窗范围内的高速信号脉冲不致重叠，声光相关峰将会达到较好的效果。并对因缩束所带来的噪声进行了模拟仿真分析，即使微小的信噪比，利用声光相关机制，噪声也会降到合理的范围。     

声光调谐滤波器用于OXC中的串音分析

分析了声光可调谐滤波器（AOTF）用于光交叉连接（OXC）系统中的各种串音。讨论了各种相应的串音抑制方法。在波长分组的概念基础上提出了一种新的不对称波长扩展OXC结构。     

巨磁阻抗传感器应用研究最新进展

利用零磁致伸缩非晶丝的巨磁阻抗(GMI)效应,可制得新一类灵敏度高、响应快、功耗低、体积小的微型磁电式传感器。介绍了目前几种基于巨磁阻抗效应的传感器,包括磁场传感器、扭矩传感器、汽车交通监测系统和生物传感器等的工作原理和特性。     

集成光学声光光通道监测仪的研究

在集成声光可调谐滤波器(IAOTF)的基础上,提出了一种新型的集成光学波导型声光光通道监测仪(OCM).介绍了该OCM的工作原理及其基本结构,对它的插入损耗、响应时间、波长范围、波长分辨率和波长精度等性能指标进行了分析与计算,并对制成的集成光学声光OCM进行了实验研究.理论分析和实验结果表明,该OCM能够对密集波分复用(DWDM)系统多路光信道的工作波长和功率同时进行监测,其插入损耗小于3 dB,响应时间小于7μs,波长监测范嗣达174 nm,波长分辨率可达0.3 nm、波长精度可达±30 pm.     

Suppression of stimulated Brillouin scattering in a single-mode fibre by an acousto-optic modulator

Stimulated Brillouin scattering in a single-mode optical fibre was fully suppressed by launching two frequency beams passed through an acousto-optic modulator. A suppression ratio up to 30 dB was obtained for a frequency difference of 500 MHz between two beams. The experimental result agrees with the theoretical estimation. The method has great advantages for optical fibre systems using a continuous high-power laser source.     

光学相干探测系统多信号处理性能的研究

针对复杂而密集的电磁环境下多信号共存与传输的特点.为解决光学相干接收系统多信号的同时处理能力,基于声光偏转原理,设计了采用声光偏转技术和光纤相干光探测相结合的测频系统,对不同频率信号的声光互作用和光束偏转进行分析,通过对多频互调的数值仿真,给出了减小多信号互作用下互调现象的解决方案.构建了实验平台,将空间光注入到光纤进...     

Interrogation of fibre-optic interferometric sensors usingacousto-optic tunable filter

A new technique for the interrogation of interferometric-based fibre-optic sensors using an acousto-optic tunable filter (AOTF) is demonstrated The scheme involves frequency shift keying (FSK) of the RF drive to the AOTF to track the shift of a single fringe peak from an interferometric sensor. Experimental results are presented for a Fizeau interferometer. The technique provides high accuracy, plus a large unambiguous tracking range free from interruptions     

All-electronic suppression of mode hopping noise in diode lasers

A simple all-electronic stabilization scheme is presented for suppression of external-cavity mode-hopping noise in diode lasers. This excess noise is generated when the laser is subjected to optical feedback and may degrade the overall performance of optical systems including sensors. Suppression of the noise has been demonstrated to improve the sensitivity of a coherent sensor by more than 23 dB