Parameters Affect the Efficiency of Acousto-Optic Modulators

In this paper, an acousto optic modulator (AOM) is designed, in which four materials are tried to be used in the head of the modulator, LiNbO3, TeO2, Ge, and SiO2. The efficiency of the modulation is considered with respect to the use of each material at four considered frequencies, 200, 300, 400, and 500 kHz. Three considered diffraction efficiency measures are computed using MatLab programming language, they are acoustic power, Bragg angle, and Q-factor. Then, the results are analyzed to decide the best design and situations that give best modulation results. The diffraction efficiency is directly proportional to the acoustic power when the operating parameters are set to suitable values. It is found that the LibNO3 based AOM has been presented higher diffraction efficiency than other materials. In such case, LiNbO3 is the best used material that showed less Brag angle and then higher efficiency relative to other used materials. Also, only LiNbO3 material is operated in Raman-Nath regime at the frequency 200 kHz, while it is operated in Bragg diffraction regime at other considered frequencies. The highest modulator efficiency of the designed acoustic modulator was about 95 % using LiNbO3 material.