Advanced multi-channel Bragg cells for 2D interferometric phase-frequency measurements

An interesting application using multi-channel Bragg cells is the 2D phase-frequency spectrum analyzer (or Acousto-Optic Interferometric Phasemeter A.O.I.P.) which was first imagined by Lambert (1965). This is an attractive solution for wide spectrum radar localization systems and the architecture is a simple extension of the common A.O. Power Spectrum Analyzer design. Feasability demonstrations of these systems have been limited to the case of medium frequency bandwidth operation as that related by R. Croppok et al. (1979) who used a 500 MHz multi-channel Bragg cell. Realizations of very large bandwidth (>1 GHz) multi-channel Bragg cell prototypes have been reported during the last ten years. The main difficulty is to achieve very good electrical features of the multitransducer, in particular good amplitude and phase balance between channels and low crosstalk level. We have developed a new conception for a low crosstalk achievement with small channel pitch. With such a new design, 4-channels with 100 μm pitch and 1 GHz bandwidth Bragg cells have been realized and we have analyzed their features in AOIP systems