Amnon Yariv

Bio: Amnon Yariv is an academic researcher from California Institute of Technology. The author has contributed to research in topics: Laser & Semiconductor laser theory. The author has an hindex of 103, co-authored 1082 publications receiving 55256 citations. Previous affiliations of Amnon Yariv include University of California, Santa Barbara & Watkins-Johnson Company.

Permanently Fixed Volume Phase Gratings in Ferroelectrics

Abstract: Volume phase holograms have been stored in a wide range of materials: silver halide photographic emulsions, dichromated gelatin films, glass, photorefractive polymers, organic materials and ferroelectric crystals. Each of these materials poses a unique set of technological problems when recording optical interference patterns as permanent index gratings. In this chapter we focus on hologram recording in ferroelectric oxide crystals, such as LiNbO3 and SrxBa1−xNb206 (SBN:x). When these materials are doped to optimize their photorefractive properties, optical interference patterns redistribute charge among traps and generate local electronic space-charge fields which are replicas of the optical interference patterns (but generally shifted in phase and spatially distorted). An index change arises from the spatially modulated space-charge field. The complex microscopic details of this process are included within a measured linear electrooptic tensor r ijk which relates the index change to the dc electric field in the non-centrosymmetric phase. Because these index gratings are electronic in origin, they are bleached by the same optical field that reconstructs them. This dynamic property is extremely useful for real time holography applications; however, for applications such as holographic data storage, permanent index gratings are desirable.

A Parallel Analog CCD/CMOS Signal Processor

Abstract: A CCD based signal processing IC that computes a fully parallel single quadrant vector-matrix multiplication has been designed and fabricated with a 2µm CCD/CMOS process. The device incorporates an array of Charge Coupled Devices (CCD) which hold an analog matrix of charge encoding the matrix elements. Input vectors are digital with 1 - 8 bit accuracy.

Gallium Aluminum Arsenide/Gallium Arsenide Integrated Optical Repeater

Abstract: A low threshold buried heterostructure laser, a metal-semiconductor field effect transistor (MESFET), and a photodiode, have for the first time, been monolithically integrated on a semi-insulating GaAs substrate. This integrated optoelectronic circuit (IOEC) was operated as a rudimentary optical repeater. The incident optial signal is detected by the photodiode, amplified by the MESFET, and converted back to light by the laser. The gain bandwidth product of the repeater was measured to be 178 MHz.The goal of integrated optoelectronics is to monolithically integrate optoelectronic components with purely electronic components. In this paper we describe the demonstration of the monolithic integration of a laser, a transistor, and a photodiode. The devices were fabricated on a semi-insulating (SI) GaAs substrate. Use of a SI substrate allows the devices to be electrically insulated from each other, and also reduces parasitics. The simple circuit configuration used serves to illustrate the basic principles of operation of lOECs in general, and sheds light on the expected performance characteristics of more complicated repeater circuits.Theory of operationA schematic circuit of the IOEC is shown in Fig. 1. Light incident on the photodiode causes a current to flow through the load resistor R,. The change in current which flows through the laser is the product of the transconductance (g ) of the MESFET and the change in voltage which appears at the transistor gate. The DC op?ical gain of this repeater is therefore,where n d and n^ are the quantum efficiencies of the photodiode and laser (from one facet), respectively. The -3 dB bandwidth of the repeater isB = -L_ _!_where C is the combined capacitance of the photodiode and MESFET. The gain-bandwidth (GxB) product of the repeater is, therefore,G x B = npdnlgm

Design of discrete, nearly-uniform Bragg gratings in planar waveguides.

Abstract: In this paper we present an efficient method for designing discrete, nearly-uniform Bragg gratings in generic planar waveguides. Various schemes have already been proposed to design continuous Bragg gratings in optical fibers, but a general scheme for creating their discrete counterpart is still lacking. Taking a continuous Bragg grating as our starting point, we show that the same grating functionalities can also be realized in any planar waveguide by discretizing it into a series of air holes. The relationship between the two gratings is established in terms of grating strength and local grating period.

Detection of low angle optical scattering by Fabry-Perot resonance.

Abstract: The effect of mirror losses on the performance of Fabry-Perot etalons has been considered by numerous investigators. I n principle, this technique can be applied in reverse, so that the losses of the reflector and (or) those of the intervening medium can be inferred from the performance of the etalon. The practical realization of the reverse process ran, heretofore, into the fol­ lowing difficulty: the performance of a lossless, and theoretically perfect, etalon can only approach its ideal behavior if the di­ vergence angle θ of the incident beam satisfies Letters to the Editor should be addressed to the Editor, APPLIED OPTICS, AFCRL, Bedford, Mass. 01731

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

A comprehensive review of zno materials and devices

Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

Digital communications

Abstract: Spread Spectrum It’s not just for breakfast anymore! Don't blame me, the title is the work of this month's guest columnist, Steve Bible, N7HPR (n7hpr@tapr.org). While cruising the net recently, I noticed a sudden bump in the number of times Spread Spectrum (SS) techniques were mentioned in the amateur digital areas. While QEX has discussed SS in the past, we haven't touched on it in this forum. Steve was a frequent cogent contributor, so I asked him to give us some background. Steve enlisted in the Navy in 1977 and became a Data Systems Technician, a repairman of shipboard computer systems. In 1985 he was accepted into the Navy’s Enlisted Commissioning Program and attended the University of Utah where he studied computer science. Upon graduation in 1988 he was commissioned an Ensign and entered Nuclear Power School. His subsequent assignment was onboard the USS Georgia, a trident submarine stationed in Bangor, Washington. Today Steve is a Lieutenant and he is completing a master’s degree in computer science at the Naval Postgraduate School in Monterey, California. His areas of interest are digital communications, amateur satellites, VHF/UHF contesting, and QRP. His research area closely follows his interest in amateur radio. His thesis topic is Multihop Packet Radio Routing Protocol Using Dynamic Power Control. Steve is also the AMSAT Area Coordinator for the Monterey Bay area. Here's Steve, I'll have some additional comments at the end.

Plasmonics: Fundamentals and Applications

Abstract: Fundamentals of Plasmonics.- Electromagnetics of Metals.- Surface Plasmon Polaritons at Metal / Insulator Interfaces.- Excitation of Surface Plasmon Polaritons at Planar Interfaces.- Imaging Surface Plasmon Polariton Propagation.- Localized Surface Plasmons.- Electromagnetic Surface Modes at Low Frequencies.- Applications.- Plasmon Waveguides.- Transmission of Radiation Through Apertures and Films.- Enhancement of Emissive Processes and Nonlinearities.- Spectroscopy and Sensing.- Metamaterials and Imaging with Surface Plasmon Polaritons.- Concluding Remarks.