Ultrahigh resolving electrooptic prism array light deflectors

A type of light deflector that shows ultrahigh resolving power is proposed. This light deflector consists of arrayed electrooptic prisms. The resolving power of this deflector isNtimes larger than that of a single electrooptic prism, whereNis the number of arrayed prisms. If the voltages applied on each crystal are all the same, the deflecting angle is discontinuous. But if the voltages are not equal to each other, it can be continuous. Experiments were done using a simple deflector. The experimental results agreed with the theory. The experimental deflector showed 50 resolved individual spots when maximum applied voltages were ± 600 V. It is clear that we can have a light deflector that shows over 600 resolvable spots easily. Current techniques are sufficient to manufacture such deflectors.     

电光偏转器的矩阵表示和应用

用光线追述的方法，导出了电光偏转器的矩阵表达式，是著名的ＡＢＣＤ矩阵的扩展，它包含了电光偏转器的时变项。井用矩阵光学的理论对由电光偏转器对构成的激光脉冲整形系统进行了研究，对实际应用的电光偏转器对参数的一致性、电脉冲的同步精度及光路排布提出了要求。     

High S/N-ratio electrooptic prism-array light deflectors

A method to construct electrooptic prism-array deflectors which is, in the author's view, the most promising device for application in digital systems is analyzed. Experiments agreed well with the analysis. An experimental deflector with nine elements showed 180 resolved individual spots when driven with a maximum voltage of ± 580 V. It is shown that this type of deflector is capable of resolving over one thousand Rayleigh points. For example, with fifty-four LiTaO3crystals with the dimension of0.2 times 0.8 times 21mm, one can have 1080 Rayleigh points for ± 64 V applied. The extinction ratio of this deflector is over 32 dB.     

Electrooptic wafer beam deflector in LiTaO/sub 3/

A novel electrooptic beam deflector is reported based on ferroelectric domain inversion extending through the thickness of a Z-cut LiTaO/sub 3/ wafer. The selective domain inversion is achieved by electric-field poling assisted by proton exchange, rather than proton exchange followed by rapid thermal annealing. The deflection sensitivity of the device was measured to be 5.0 mrad/KV. This is 93% of the theoretical value for this geometry, and a significant improvement over the value of 80% of theoretical previously reported for a waveguide deflector. This improvement is attributed to the new domain inversion process. No degradation of deflection sensitivity is observed up to the frequency of 300 KHz, which is then limited by the response time of detectors.     

High-speed optical Fourier transformer

A new type of high-speed signal processing or analyzing device-the picosecond Fourier transformer-is proposed. The device can be used to obtain the Fourier transform of the time-dependent intensity of an optical signal. The device makes use of the spatially distributed electrooptic modulator or deflector, and has the potential for terahertz bandwidth and picosecond time resolution. Practical devices are considered and their performances (bandwidth, frequency resolution, etc.) are discussed. The operation of the proposed device is demonstrated in the microsecond range by a preliminary experiment using LiTaO3e-o deflectors.     

不同几何结构电光偏转器比较研究

为了发展性能优良的电光偏转器,采用傍轴近似分析了级联棱镜电光偏转器的折射率梯度等效表达式,总结出了不同几何结构电光偏转器的偏转角和偏转轨迹公式,在此基础上比较研究了4种不同几何结构电光偏转器的偏转特性和偏转轨迹,比较分析了梯形、喇叭形和抛物线形几何结构电光偏转器的偏转灵敏度,为较大角度电光偏转系统的设计提供了有意义的参考。     

Control Schemes for Driving Electro-optic Array Beam Deflectors

The beam deflectors based on electro-optic phased array（EOPA） is mainly described, and then an analysis on existing control schemes for driving the EOPA beam deflectors, based on custom hard-wired electronics or based on software in a microcontroUer, is made. Compared with these, a driving and control system for a multi-channel EOPA beam deflector is presented, in which the control assignment is implemented with a field programmable gate array（FPGA） chip. For different performance requirements, two control schemes, one with the serial scheme and another with the parallel scheme, have been explored and rapidly prototyped in Xilinx FPGA chips. With the control structures for the EOPA beam deflector, scanning rates of 588 kHz and 5 MHz can be respectivelv reached.     

Electrooptic materials for digital light beam deflectors

The technology of digital deflectors made significant progress in the past. The success of this development was primarily based on the advances made in the preparation of electrooptic materials. The selection criteria are described here for a material suitable for the particular application under consideration, and a survey is made of the most promising electrooptic materials, both solid state and liquid. The list of solid-state materials comprises representatives of the class of oxygen octahedra ferroelectrics, KDP isomorphs, and AB-type compounds. A section on Kerr liquids begins with considerations for the optimization of the molecular structure and gives experimental results on some newly synthesized materials. Further, the impurity conduction phenomena that are important to the technical performance are described in detail. The final section reviews the present state of digital deflector development.     

Simulations of Ti:LiNbO3 waveguide modulators-acomparison of simulation techniques

The modulation characteristics of several Ti:LiNbO₃ waveguide devices were simulated. For the electrooptic effect, both a spatially dependent and a uniform modulation field were considered. Both the three-dimensional beam propagation method and the two-dimensional beam propagation method with effective index were used in the simulations. The results of simulations and measured device performance are compared     

A novel optical bistable multiple-quantum-well phase modulator

The authors present a new type of optically bistable phase modulator utilizing a self electrooptic effect device (SEED) integrated with an electrooptic wavelength modulator. An electrically bistable SEED, operating on the principle of the quantum-confined Stark effect, controls the bias voltage across an electrooptic waveguide phase modulator to produce optical bistability. A control signal at 0.848 μm, corresponding to the first electron to heavy hole exciton transition in GaAs/AlGaAs multiple-quantum-well is used to switch 1.152 μm light propagating through a waveguide in a direction normal to the control beam     

时空变换脉冲整形系统中实现光束复原的一种新方法

提出了时空变换脉冲整形系统中光束复原的一种新方法：用单模光纤代替通常时空变换法中的第二个电光偏转器。当改变调制狭缝的宽度时，获得了脉宽在740ps～4．5ns连续变化的整形脉冲，而且输出光束质量好。此方法降低了对关键元件电光偏转器的要求，提高了可靠性，简化了系统。     

楔形偏转线圈和平板电极静电偏转器的偏转场的计算方法

本文介绍楔形截面的偏转线圈和平板电极的静电偏转器的偏转场的计算方法。楔形线圈可以组合成形状多样的组合磁偏转器,有利于通过适当改变场分布形状,进一步减小偏转象差。矩形平板电极静电偏转器的优点是结构简单,有希望用它组成多电子束系统的偏转器阵列。根据上述两种偏转器的计算方法,已建立起实用的计算机程序,计算了一些典型结构偏转器的场分布。     

A Planar Electrooptic Beam Splitter with a Zig-Zag Electrode

A new planar electrooptic beam splitter with a zig-zag electrode is proposed, studied, and demonstrated. The device is simple in its electrode configuration, hence, it is easier to be fabricated and has a potential to operate at higher speeds. Theoretical analyses on a single element of electrodes, as well as on the array structure, have been carried out, and experimental devices have been realized on LiNbO/sub 3/ to demonstrate its characteristics. The experimental results show that the device has a deflection power two times greater than that of a beam splitter with conventional electrodes. In addition, an analysis of the incident angle of the optical beam onto the device shows that the device can be used as a pure beam splitter, a beam deflector, or a combination of the two.     

Digital light deflectors

Several electrooptic digital light deflection techniques have been proposed. The maximum number of resolvable deflection positions for all methods is determined, essentially, by economic reasons, the tolerable amount of background fight, and aberrations. In this paper, three different types of deflection methods (split angle, total internal reflection, Wollaston prism) are described. Design, construction details and performance of three deflector models are reported. Combined deflection systems use the advantageous properties of each of these methods to economically obtain the maximum number of resolvable deflection positions. A suggested combination to achieve 1024 × 1024 positions arranged in a two-dimensional field would consist of one total internal reflection stage, seven stages of split angles, and two stages of Wollaston prisms for each dimension.     

4×4 GaAs/AlGaAs optical matrix switches with uniform devicecharacteristics using alternating Δβ electrooptic guided-wavedirectional couplers

Integrated 4×4 GaAs/AlGaAs optical matrix switches constructed from 12 electrooptic directional couplers have been realized. In order to achieve uniform device characteristics, molecular beam epitaxy and reactive ion beam etching were chosen as the crystal growth technique and waveguide fabrication technique, respectively, in addition to the simplified tree structure as a matrix switch architecture. As a result, matrix switches with quite uniform device characteristics, such as small switching voltage deviation and little path dependence in ±0.5-dB propagation loss, have been realized     

High-frequency, stripline, multireflection electrooptic beam deflectors

A novel electrooptic (EO) beam deflector has been designed through numerical simulation. This stripline lithium tantalate device has the potential to electrooptically modulate the deflection of an optical pulse at unprecedented frequencies. Velocity matching of the optical pulse to a high-frequency transmission line signal is achieved through reflections of the fast optical pulse. An optimal design criterion is formulated for this device. Deflection capability is estimated to be 8/spl deg/. The device is intended for use in deflection-based optical analog-digital (A/D) conversion.     

Optimal design of a low-loss 2-bit electrooptic analog-to-digital converter

The structure of the optical waveguide of 2-bit electrooptic A/D converter with proton-exchange micro prisms is optimized by the finite-difference beam propagation method （FD-BPM） The electrode parameters of the converter are optimized by conformal mapping. The optimal parameters are a half- wave voltage of Vπ = 4.5 V and a bandwidth of △f = 1.4 GHz. A normalized transmitted power of 69.75% is obtained by FD-BMP and the output waveguide gap is 300 μm.     

Coupling efficiencies in reflective self-organized lightwave network (R-SOLNET) simulated by the beam propagation method

The reflective self-organized lightwave network (R-SOLNET) enables the formation of self-aligned waveguides in the photorefractive (PR) material between misaligned optical devices by introducing a write beam. The incident write beam from one device and the reflected write beam from the second device induce self-focusing in the PR material and construct a coupling waveguide. A wavelength filter on the waveguide edge is used to facilitate the reflected beam. The beam propagation method reveals that R-SOLNET exhibits higher coupling efficiencies and better tolerances than the one-beam-writing SOLNET and the free-space coupling. The apparent usefulness of R-SOLNET is remarkable for gaps wider than 100 /spl mu/m in 8-/spl mu/m-wide waveguide circuits. For 240-/spl mu/m gap, coupling efficiency better than 50% can be achieved even when the lateral misalignment is as large as 4 /spl mu/m. The results indicate that R-SOLNET may be useful for vertical waveguide constructions of optical z-connections in three-dimensional intrachip optical interconnects and switching systems, as well as for self-aligned optical couplings with devices that cannot emit write beams such as vertical-cavity surface-emitting lasers, photodetectors, and electrooptic switches.     

Integrated optical device with second-harmonic generator,electrooptic lens, and electrooptic scanner in LiTaO3

This paper reports the first demonstration of an integrated optical device in z-cut LiTaO₃ that contains the following three functional parts: a quasiphase-matched second-harmonic generation (SHG) grating, an electrooptic (EO) lens, and an electrooptic scanner. The SHG device consists of channel waveguides passing through periodic domain-inverted gratings. The frequency of the input infrared (IR) light at 864 nm was doubled into blue light at 432 nm. A stack of EO lenses was used to collimate the light from the channel waveguide. The measured beam size at the output facet for various applied voltages to the lenses agreed with simulation. After collimation, light passes through an EO scanner that controls the angle of the output beam. A scanning sensitivity of 17 mrad/kV was measured for the scanner, compared to the calculated value of 15 mrad/kV