David Robert Wight

Novel 1‐to‐N way integrated optical beam splitters using symmetric mode mixing in GaAs/AlGaAs multimode waveguides

We report the demonstration of novel GaAs/AlGaAs integrated optical 1‐to‐N way beam splitters which use symmetric mode mixing in center‐fed multimode planar waveguides. Each device has one single‐mode input guide, a carefully chosen length of parallel sided multimode guide, and N equally spaced single‐mode output guides. The mixing of symmetric modes shares the input light equally between the output guides by a symmetric form of the self‐imaging process. We demonstrate experimentally that this type of beam splitter can be used to divide power equally, with high accuracy and low loss, between the N output guides, for values of N between 2 and 20.

Novel 1×N and N×N integrated optical switches using self‐imaging multimode GaAs/AlGaAs waveguides

We report the demonstration of novel multiway GaAs/AlGaAs electro‐optic waveguide switches which incorporate self‐imaging planar multimode waveguide splitters and recombiners interconnected by single‐mode guides. Each device consists of one or more input guides, a multiway splitter, an array of individually addressed electro‐optic waveguide phase shifters, a multiway recombiner, and an array of output guides. By controlling the voltage applied to the electro‐optic guides, light from any one input guide can be switched to any one output guide. We present experimental results for 1×10 and 10×10 devices. Typical values for switching uniformity, maximum crosstalk, and insertion loss were ±9%, −10 dB, and −12 dB, respectively.

Optimization of deep-etched, single-mode GaAs-AlGaAs optical waveguides using controlled leakage into the substrate

This paper presents a detailed experimental and theoretical study of the properties of deep-etched GaAs-AlGaAs optical waveguides designed using a version of the spectral index method which predicts mode losses due to leakage through the lower cladding into the high index GaAs substrate. By predicting and measuring the mode losses due to this mechanism as a function of guide width, we show that waveguides formed by reactive ion etching through the core to the lower cladding layer can be both low-loss (0.2 dB/cm) and single-mode even with core thicknesses and guide widths as large as 4.8 and 5.6 /spl mu/m, respectively. We demonstrate the advantages of this type of guide for making compact integrated optic devices.

Novel phased array optical scanning device implemented using GaAs/AlGaAs technology

A novel type of optical beam scanning device based on the same principle as a phased array radar has been made and demonstrated. This phased array optical scanning device consisted of a uniformly illuminated array of ten closely spaced, single mode GaAs/AlGaAs electrooptic waveguides, each of which was individually addressed to give more than 2π radians of optical phase control. This gave a line of ten point sources of light on a 3 μm pitch at the output face of the array. By independently phase shifting these light sources the output wavefront was controlled to scan a 2° wide beam through 20° in the far field.

A phased array optical scanning (PHAROS) device used as a 1-to-9 way switch

An optical switch is demonstrated which uses a phased array of 30 closely spaced, individually addressed electrooptic AlGaAs-GaAs waveguides to focus and steer a light beam under electronic control in a planar output waveguide. A small and potentially very high speed 1-to-9 way optical switch, (with -15 dB of crosstalk) was made by placing an array of nine output waveguides at different positions in a focal plane 1 mm from the end of the electrooptic array. >