Acoustooptic modulator intensity servo.

ABSTRACT

A device has been constructed that combines optical isolation and amplitude noise reduction by the use of a servo controlled acoustooptic intensity modulator. The isolation can, in principle, be perfect while the noise reduction can be significant up to about 100 kHz and as large as 80 dB at low frequency. This performance is accomplished by applying negative feedback around an acoustooptic modulator, servoing the intensity of the Bragg diffracted beam to a constant value.