Dynamic processes in an acousto-optic laser beam intensity stabilization system

• A system for laser beam intensity stabilization is studied.
• The system is based on an acousto-optic modulator applied as a regulating device.
• A differential equation describing the system behavior is derived.
• Influence of acousto-optic nonlinearity and feedback signal delay is examined.
• Experimental investigations are carried out with a paratellurite modulator cell.

We present results of theoretical and experimental study of a laser beam intensity stabilization system with an acousto-optic modulator applied as a regulating device in the servo circuit. A differential equation is obtained which describes dynamic processes in the system with regard to nonlinearity of the acousto-optic modulation characteristic and the servo signal delay in the feedback loop. It is shown that the stabilization factor is defined by the signal transmission coefficient in the feedback circuit and by the operating point position in the modulation characteristic. Experimental investigations are fulfilled with an acousto-optic cell made of a paratellurite single crystal. The realized system provides light intensity stabilization with maximal stabilization factor as high as 78 in the frequency band from 15 to 180 Hz.