Optimization and comparison of the characteristics of optical interference discriminators

The laser frequency can be stabilized with aid of the an external highly stable Fabry–Perot interferometer. It is proposed that light reflected from this interferometer, rather than the transmitted light, be recorded in the stabilization procedure. It is shown that this improves the sensitivity by a factor of 4–6 and increases the signal/noise ratio by at least 10 dB. In the modulation regime when the modulation amplitude is small and the predominantly reflection variant is adopted, the ratio of the signal to the shot noise of a photodetector can reach (other conditions being constant) a value of 20–30 dB. A calculation is made of the optimal parameters of both variants of a discriminator which has the same length, same optical power, and same absorption in the mirrors (assumed to be small).