Effect of Square Shaped Acousto–Optic Modulators on the Bragg Diffraction

The COMOSOL multiphysicsis used to design various optical systems, including the design of the acousto-optic modulator system. Its work depends on the special inputs of the program, such as the characteristics of the laser used and the frequencies of the sound waves. A square modulator was designed with dimensions 3x3 mm, and a quartz crystal was used, in which the interaction of light and sound occurs. Different number of orders diffraction are generated called the Bragg angle, and their number varies with different inputs. The modulator is created by entering the value of the radio frequency up to 100 volts. Through our results, the efficiency increases at the frequency of 400 kHz after changing the frequencies of 200, 300 and 400 kHz. The values of the stress are: 1.24 × 10⁶Pa, 1× 10⁶Pa, 3.8× 10⁶Pa, and the estimated shift is about 0.7, 0.4 and 0.9 mm, there were three frequency values considered: 200, 300, and 400 kHz. respectively. The far field shape show two orders are appeared at 200 kHz and 300 kHz frequencies they are: zero order and first order but they are different in the value of Bragg angles but in 400 kHz shown approximate three orders, they are: zero, first, and new generation of second order with the different in the value of Bragg angles.