Subharmonic generation of ultrasonic waves in amplifying CdS

The generation of even subharmonic ultrasonic shear waves in photoconducting CdS was detected by using Brillouin scattering of a laser beam for fundamental frequencies in the 1000-MHz region. By means of a microwave cavity technique, the fundamental was transduced directly into amplifying CdS which had a gain peak in the subharmonic frequency region.