Direct acousto-optical spectrum analysis of ultra-high-frequency radio signals based on the collinear wave heterodyning in a medium with dispersive acoustic losses

Abstract

This work is devoted to the problem of improving the frequency resolution inherent in a parallel acousto-optical spectrum analysis via involving an additional nonlinear phenomenon into the data processing. In so doing, we examine possible application of the wave heterodyning to the real-time scale acousto-optical analysis of the frequency spectrum belonging to various ultra-high-frequency radio-wave signals. The nonlinear process of wave heterodyning is realized through providing a co-directional collinear mixing of the longitudinal acoustic waves of finite amplitudes. This process, which is beforehand studied theoretically, allows us either to improve the frequency resolution of spectrum analysis at a given frequency range or to increase by a few times the current frequencies of radio-wave signals under processing. The theoretical findings are used in our experimental studies aimed at creating a new type of acoustooptical cell, which is able to improve the resolution inherent in acousto-optical spectrum analyzer operating over ultra-high- frequency radio-wave signals. In particular, the possibility of upgrading the frequency resolution through the acoustic wave heterodyning is experimentally demonstrated using the cell made of lead molybdate crystal. The obtained results demonstrate practical efficiency of the novel approach presented.