Optics and Quantum Electronics

Contains reports on eleven research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)National Science Foundation (Grant ECS83-05448)National Science Foundation (Grant ECS83-10718)National Science Foundation (Grant ECS82-11650)National Science Foundation (Grant ECS84-06290)U.S. Air Force - Office of Scientific Research (Contract AFOSR-85-0213)National Institutes of Health (Grant 1 RO1 GM35459

Optics and Quantum Electronics

Contains table of contents for Section 2 and reports on eighteen research projects.National Science Foundation (Grant EET 87-00474)Joint Services Electronics Program (Contract DAAL03-86-K-0002)Joint Services Electronics Program (Contract DAALO3-89-C-0001)Charles Stark Draper Laboratory (Grant DL-H-285408)Charles Stark Draper Laboratory (Grant DL-H-2854018)National Science Foundation (Grant EET 87-03404)National Science Foundation (Grant ECS 84-06290)U.S. Air Force - Office of Scientific Research (Contract F49620-88-C-0089)AT&T Bell FoundationNational Science Foundation (Grant ECS 85-52701)National Institutes of Health (Grant 5-RO1-GM35459)Massachusetts General Hospital (Office of Naval Research Contract N00014-86-K-0117)Lawrence Livermore National Laboratory (Subcontract B048704

Optics and Quantum Electronics

Contains reports on eleven research projects.National Science Foundation (Grant EET 87-00474)Joint Services Electronics Program (Contract DAALO03-86-K-O002)Charles Stark Draper Laboratory, Inc. (Grant DL-H-2854018)National Science Foundation (Grant DMR 84-18718)National Science Foundation (Grant EET 87-03404)National Science Foundation (ECS 85-52701)US Air Force - Office of Scientific Research (Contract AFOSR-85-0213)National Institutes of Health (Contract 5-RO1-GM35459)US Navy - Office of Naval Research (Contract N00014-86-K-0117

Session 3432 A Remote Wireless Sensing and Control Laboratory

A laboratory has been designed to provide students with hands-on experience integrating disparate technologies in laboratory exercises and independent projects. Specifically, three areas have been selected for the development of applications: 1) intelligent sensing, 2) web-based data acquisition and control and 3) wireless communication systems. Students can choose modules from any of these three areas to enhance their own work. The intelligent sensing modules give students easy access to video camera and microphone data streams so they can rapidly develop interfaces responsive to those modalities. Students can connect analog and digital electronics they have designed to the web-based modules that consist of small, inexpensive, web-servers. This lets them use a web browser for sophisticated user interfaces, for remote control over the internet, or for both. Only minimal electronics resources (i.e., a serial port) and student time are required. Bluetooth^TM technology was chosen to implement the wireless modules. Software drivers have been written to allow an inexpensive Bluetooth receiver/transmitter set to be used to network small microcontrollers so that they can perform wireless data acquisition and control. This nicely complements the web-based system. The students also have access to a Bluetooth protocol analyzer so they can see individual packets as they move around the wireless network. This is both a useful instructional aid as well as an important debugging tool for students working with the receiver/transmitter sets. Projects can incorporate any or all of these modules to allow students across disciplines to develop sophisticated remote sensing and control applications. Typical applications that integrate all three components include an intelligent monitoring ..

The Extinction Ratio In Optical Two-Guide Coupler Δβ Switches

Two-guide Δβ optical couplers that operate as on-off switches are reexamined using the exact eigenmodes of a slab waveguide model of the coupler. Two-section alternately detuned couplers, with the first section detuned by D and the second section by -D, are treated. The input/output configurations analyzed are case (1) where a single output guide is connected to the same guide of the coupler as the input guide, and case (2) where a single output guide is connected to the coupled guide. For both cases, ideal switching, i.e. complete extinction of the off state, can be obtained in the two-section Δβ coupler over a wide range of coupler lengths. The results differ from those of conventional coupled-mode theory, however, in that complete extinction can be obtained when the two sections of the coupler have equal lengths only in a few special cases. Over most of the total coupler length range in which ideal switching is possible in both input/output configurations, the lengths of the two sections cannot be equal if complete extinction is to be obtained

Cross Power And Crosstalk In Waveguide Couplers

The operation of two-guide couplers is re-examined to include the effects of cross power. Two two-guide coupler structures that operate as on-off switches are analyzed using both the exact eigenmodes of a slab model of the coupler and a coupled-mode theory that takes cross-power effects into account. The two coupler configurations analyzed are with the output guide on the same side as the input guide and on the side of the coupled guide. For the proper choice of the length of the coupler in the first case, the waveguide detuning can be adjusted so that ideal switching behavior can be achieved. For the second case, full on-off switching is not possible. Excellent agreement is found between results of the coupled-mode theory and exact slab analyses

Evaluation Of Refractive Index Approximations Used For Mode Determination In Multiple Quantum Well Slab Waveguides

Approximations commonly used to determine the effective indexes of the guided modes of optical waveguides formed using multiple quantum well materials are compared to the exact solutions in the slab waveguide model. Modeling the quantum well region as a single homogeneous layer with an average index of refraction is shown to produce results in close agreement with exact values of the effective index. A geometrically weighted average of the indexes provides the most accurate approximation for typical values of index and layer thickness of GaAs-Al(x)Ga(1-x)As quantum well waveguides

Refractive Index Approximations From Linear Perturbation Theory For Planar MQW Waveguides

The mode powers and propagation constants for planar multilayer waveguides formed with multiple quantum well (MQW) materials and with the MQW layers replaced by a single uniform layer are compared. By considering linear perturbations of the solutions of the wave equation, the optimal choice of average for the dielectric constant of the substituted single layer is determined. For the case of TE modes, minimal error in the propagation constant is predicted if a weighted average of the dielectric constants of the MQW materials is used. For the case of TM modes, using a weighted average of the reciprocal of the dielectric constants is predicted to yield the minimum error. Numerical results confirm these predictions. This substitution is applied to a waveguide with a single MQW-guiding region and the relative magnitude of the errors in the power distribution and propagation constant for symmetric and antisymmetric TE modes are explained

The Extinction Ratio In Optical Two-Guide-Coupler Δβ Switches With Asymmetric Detuning

Two-guide asymmetrically detuned Δβ optical coupler switches with two equal-length sections that operate as on-off switches are examined by means of the exact eigenmodes of a slab waveguide model of the coupler. Two input/output configurations are analyzed, namely (1) where a single output guide is connected to the same guide of the coupler as the input guide, and (2) where a single output guide is connected to the coupled guide. For both cases, ideal switching, i.e. complete extinction in the off state, can be obtained in the two-section Δβ coupler over a wide range of coupler lengths. The results differ from those of conventional coupled-mode theory in that when the two sections of the coupler are antisymmetrically detuned, i.e. Δ = Δ /sub 1/=- Δ /sub 2/, complete extinction can be obtained only in a few special cases.