Acousto-Optic Interferometric Spectrum Analyzer With Direct Rf Frequency Output

Abstract

The purpose of this study was to investigate a new heterodyne AO spectrum analyzer configuration and provide preliminary results for possible applications in real-time spectrum analysis. This spectrum analyzer was unique in that it used an interferometric configuration to generate direct channelized RF outputs at the input frequencies. Acousto-optic spectrum analyzers use the acousto-optic interaction to create a Fourier plane of light in space. Simultaneous spectrum analysis of multiple signals is possible in real-time in a configuration that continuously receives all input signals due to the channelization of the acousto-optic cell. In a nonheterodyne configuration, the frequency is read as positions in spacer. The interferometric spectrum analyzer floods the frequency plane with coherent light to recover the phase information which is modulated onto the diffracted beam by the Bragg cell. Frequency is read spatially but the signal output by the spectrum analyzer can be retransmitted for phase analysis, relative power readings, and other purposes as well. In addition, and perhaps most importantly, the dynamic range is increased by the heterodyne structure.