光学玻璃均匀性的全息法检验

光学玻璃的均匀性是衡量其性能的重要指标之一,因此,在实际应用中对它的精密检测有着重要意义。全息干涉技术是一种高精度的无损检测技术,较为详细地论述了二次曝光全息技术在玻璃均匀性测量方面的应用,做了一些理论上的推导和实验方法上的探索与尝试,并对其可行性进行了理论分析和实验验证,该结果与理论符合较好。而且把这种方法运用于普通玻璃材料,也能够定性地分析其均匀性。这种检测方法是非接触性的无损检测,可以方便用白光光源再现,而且检测精度较高。     

显微全息的一种光路设计

一、引言 显微全息术是显微和全息相结合的技术,其特点是将微小物体通过显微技术进行放大,通过全息技术进行三维信息贮存,这两种技术的先后次序是可以互换的,因此显微全息术分两种类型,一种是用显微术将标本图像放大再记录其全息图称预放大;另一种是先拍摄标本的全息图再用显微镜进行观察称后放大。显微全息术最突出的优点是可以拍摄生物活标本的瞬态全息图,便于进行三维观察或“冻结”它的某个瞬态进行长期保存。这种情况通常需使用脉冲激光器或高功率连续激光器,这些光源价格昂贵,而且由于照射在活标本上的激光束功率密度高,往往会影响甚至破坏它的正常生长。本文介绍的一种显微全息光路,它无需庞大的防震     

Low-noise optical receiver for high-speed optical transmission

This paper describes the design of a low-noise optical receiver using Si bipolar transistors for high-speed optical transmission. The conventional common emitter-common collector circuit (CE-CC pair) and Darlingtou circuit (transimpedance amplifiers with parallel feedback) are studied. Optimal CE-CC pair collector-biasing current for attaining minimum noise current with a 400-MHz bandwidth is 2.7 mA, and less than 1.2 mA for the Darlington circuit. It is confirmed that the Darlington circuit is better than the CE-CC pair in signal-to-noise ratio by about 1.5 dB. The low-noise Darlington optical receiver with a Ge-avalanche photodiode has achieved an optical sensitivity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10^-10. This is a 2.5-dB improvement in optical sensitivity over that of the conventional CE-CC receiver.     

Low-noise optical receiver for high-speed optical transmission

This paper describes the design of a low-noise optical receiver using Si bipolar transistors for high-speed optical transmission. The conventional common emitter-common collector circuit (CE-CC pair) and Darlington circuit (transimpedance amplifiers with parallel feedback) are studied. Optimal CE-CC pair collector-biasing current for attaining minimum noise current with a 400-MHz bandwidth is 2.7 mA, and less than 1.2 mA for the Darlington circuit. It is confirmed that the Darlington circuit is better than the CE-CC pair in signal-to-noise ratio by about 1.5 dB. The low-noise Darlington optical receiver with a Ge-avalanche photodiode has achieved an optical sensitiyity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10^-10. This is a 2.5-dB improvement in optical sensitivity over that of the conventional CE-CC receiver.     

菲涅耳波带板在光学扫描全息术中的作用

本文研究了非运动卷积中的投影式卷积装置，并讨论了二函数在该装置中的卷积与解卷积过程，为了验证在光学扫描全息术中菲涅耳波板与物体波函数之间卷积的作用，本文利用投影式卷积装置实现了菲涅耳波带板与物体波函数之间的卷积与解卷积过程，文中给出了实验装置及实验结果。     

Modeling high-speed optical transmission systems

Computer simulation of a 2.5-Gb/s intensity-modulated/direct-detected optical system with high path dispersion is described. This simulation, based on single-mode laser diode rate equations, includes transmit and receiver circuit filtering, receiver circuit noise, avalanche photodiode noise, fiber dispersion, and laser chirp. The rate equations are sufficiently general to model mode-offset distributed feedback laser diodes. The system power penalty, due to laser chirp and fiber dispersion, is calculated using Gaussian quadrature numerical integration. By simulating a population of some 12800 laser diodes and correlating the performance of each laser in a transmission system with its spectral characteristics, it is possible to deduce laser specifications that will assure satisfactory operation in long-span links. These results are used to study a laser diode specification under consideration by CCITT, and, by studying the simulated laser line shapes, some modifications to the CCITT specification are considered     

1550-nm volume holography for optical communication devices

The two-lambda method can provide a strategic approach to implement all-optical devices for communication wavelength division multiplexing (WDM) signal processing based on volume holography. By writing holograms at 488 nm in LiNbO/sub 3/:Fe and reading them in the third window of optical communication systems (1550 nm), the feasibility of WDM demultiplexers and holographic memories for digital bytes is here demonstrated.     

Formation of self-trapped filaments by self focusing

It is shown that under suitable conditions the self-focusing of a Gaussian beam can lead to the self-trapped solution of Chiao et al. [2]. The properties of the focused region are described in detail.     

高速光纤通信系统中PMD补偿算法的研究

第一次引入CPSO算法作为二阶PMD反馈补偿算法,克服T原有PSO算法容易陷入局部最优值的缺点.叙述了算法流程,比较了两种算法的特点,分析了CPSO算法在收敛过程中的优越性.最后在4×40Gb/s的仿真系统中对CPSO反馈控制算法进行了验证.     

A high-speed GaAs MESFET optical controller

Optical interconnects are being considered for control signal distribution in phased array antennas. A packaged hybrid GaAs optical controller with a 1:16 demultiplexed output that is suitable for this application is described. The controller, which was fabricated using enhancement/depletion mode MESFET technology, operates at demultiplexer-limited input data rates up to 305 Mb/s and requires less than 200 μW optical input power     

Recent progress on high-speed optical transmission

The recently reported high spectral efficiency (SE) and high-baud-rate signal transmission are all based on digital coherent optical communications and digital signal processing (DSP). DSP simplifies the reception of advanced modulation formats and also enables the major electrical and optical impairments to be processed and compensated in the digital domain, at the transmitter or receiver side. In this paper, we summarize the research progress on high-speed signal generation and detection and also show the progress on DSP for high-speed signal detection. We also report the latest progress on multi-core and multi-mode multiplexing.     

A proposed new high-speed optical detector

The small-signal optical detection properties of the barrier injection transit-time (BARITT) diode structure are presented. At low frequencies, the device behaves as a punch-through phototransistor while at frequencies near the transit-time frequency the device is capable of additional gain due to negative-resistance reflection-type amplification.     

高速光交换机竞争调度策略

在光交换网络中,当同一波长两个或多个光分组同时离开光交换机的同一个输出端口时将会发生对输出端资源的竞争,竞争失败的光分组将受阻,如何有效地调度将使光交换系统性能受到很大影响,文章综述了目前解决光交换网分组冲突的几种方案,阐述了各种解决方法的原理、实现方式及特点,展望了今后可能采用的最佳竞争调度方案.     

Packaging and integration of high-speed optical components

Packaging of high-speed optical components is a complex process involving many interdisciplinary engineering efforts. The design of a packaged component is an interesting combination of optical, mechanical, electrical, and process engineering. This article shows how solving assembly and packaging problems can accelerate the progress in microsystem applications. In this article, automated assembly integrates over 50 specific functions into an array for a low-cost component. The techniques are applicable for other measurement microsystems in different fields of applications for measurement, control, and communications.     

Study of a novel amplitude-phase modulation IRZ-MSK in high-speed optical fiber transmission system

In this paper, a novel amplitude-phase modulation format, inverse-return-to-zero minimum shift keying (IRZ-MSK), is proposed. A scheme to realize the IRZ-MSK is introduced, and especially a method of demodulating the phase branch is presented. The influence of different duty cycles on the performance of the IRZ-MSK is discussed. Numerical simulations and analysis are performed, and the comparison between the 70% IRZ-MSK and the NRZ-MSK is made. The phase branches of 70% IRZ-MSK and the NRZ-MSK almost have the same dispersion tolerance, and the amplitude branch of 70% IRZ-MSK has a better dispersion tolerance than that of the NRZ-MSK when the residual dispersion is larger than 1.9 ps/nm/km. For the nonlinear tolerance, the EOP of the IRZ-MSK phase branch and amplitude branch reduces 0.5 dB and 3.8 dB than those of the NRZ-MSK respectively, when the launch power is 4 mW and dispersion is completely compensated. Meanwhile, the BER curves of the NRZ-MSK and IRZ-MSK are also made. The results show that, our proposed IRZ-MSK can not only improve the spectral efficiency, but also greatly mitigate the dispersion and nonlinear effects.     

Rapid and precise read-out of terahertz sensor by high-speed asynchronous optical sampling

High-speed asynchronous optical sampling is used for the rapid and precise determination of transmission resonances of terahertz surface sensors based on asymmetric double split ring resonator arrays. The sensor response represented by a characteristic resonant frequency is determined to 0.66113 THz with an accuracy of ±325 MHz within 2 seconds of read-out time.     

Optimum beam size for high-speed drawing of LSI patterns by variably shaped rectangular electron beams

The drawing time of the vector-scan electron-beam exposure systems employing variably shaped rectangular (VSR) beams is calculated and the optimum value of the maximum dimension of the rectangle is found which makes the drawing time minimum under the condition that the edge slope is within a certain fraction of the linewidth.     

Seismic imaging by holography

During the last half century, seismic imaging techniques have seen steady improvements. With the recent advent of relatively cheap and readily available computers, many complicated algoriths for obtaining seismic images that were formerly only theoretical curiosities can now be implemented. This paper reports on the applications of yet another imaging technique, namely holography, with particular emphasis on Fourier transform holography. A variety of laboratory, field, and computer experiments ate described together with several anticipated practical applications, and it is shown among other things that certain image enhancement techniques based on holography can significanfly improve siesmic images and image-related data.