<title>Advanced multichannel Bragg cells for 2D interferometric phase-frequency measurements</title>

Abstract

Two-dimensional acousto-optic architectures are considered as very powerful systems in the field of information processing. An interesting application using multi-channel Bragg cells is the 2-D phase-frequency spectrum analyzer (or Acousto-Optic Interferometric Phasemeter AOIP) which was first imagined by Lambert in 1965. This is an attractive solution for wide spectrum radar localization systems and the architecture is a simple extension of the common AO Power Spectrum Analyzer design. Feasibility demonstrations of these systems have been limited to the case of medium frequency bandwidth operation as that related in 1979 by R. Croppok et al., who used a 500 MHz multi-channel Bragg cell. Recent developments have been made by using GaP material which presents a crystallographic solution for a self- collimated acoustic beam propagation. This presents an advantage for the acoustic crosstalk reduction. But the reproducibility and the reliability of this material are not assured. We have developed a new conception for a low crosstalk achievement with small channel pitch. With such a new design, 4-channels with 100 micrometers pitch and 1 GHz bandwidth Bragg cells have been realized and we have analyzed their features in AOIP systems.