Optoelectronic Feedback Influence on the Spectral Transmission of Collinear Acousto-Optic Diffraction

The presence of light beams divergence affects the characteristics of acousto-optic (AO) diffraction. It leads to a decrease in the AO interaction efficiency and transformation of the AO devices transmission function - its bandwidth increases and the side lobes are smoothed. In this paper we propose to compensate the light divergence effect on the collinear AO diffraction transmission functions shape applying an optoelectronic feedback circuit connecting the AO cell optical output and its piezoelectric transducer. It is shown that the introduction of feedback makes it possible to narrow the passband and increase the spectral contrast of the transmission function. Unfortunately, feedback does not help to increase the maximal possible AO diffraction efficiency as it is determined by the optical beam divergence, since the feedback does not affect the AO device transfer function