Gain of electromagnetic radiation traveling in a semiconductor subjected to magnetic and ultrasonic fields

A calculation is made of the gain experienced by an electromagnetic wave in a semiconductor subjected to magnetic field and ultrasonic fields. It is shown that the gain can be 1–500 for a wide range of the parameters. Analytic expressions are obtained for the frequency depencence of the real part of the highfrequency conductivity when the pump power, ultrasonic wavelength, and temperature of the semiconductor are varied.