Impact Analysis of the Acousto-optic Tunable Filter Design on Peak Diffraction Efficiency

The Acousto-optic Tunable Filter (AOTF) is composed of an anisotropic acousto-optic crystal and a piezoelectric transducer, which has unique advantages such as rapid tuning speed, wide wavelength coverage, and high spectral resolution. However, the major challenge in designing AOTF is achieving a higher peak diffraction efficiency. As the acoustic wave generated by the piezoelectric transducer could reflect several times on the boundary of the acousto-optic crystal of an AOTF, different crystal cuts might cause different acoustic modes in AOTF, resulting in different peak diffraction efficiency of the AOTF. This article proposed a method to calculate the two-dimensional steady-state acoustic field in the acousto-optic crystal of AOTFs with variable acoustics cut angles and absorption cut angles by decomposing the acoustic field into a series of orthogonal acoustic modes. The results show that the incident light would simultaneously interact with those different acoustic modes, leading to different peak diffraction efficiency of the AOTF.