Cross-relaxation quantum amplifier operating at 22.2 GHz

A cross-relaxation ruby quantum amplifier operating at 22.2 GHz was constructed. The 4→3 signal transition and the 2→4 pump transition were used in the θ=76° and 90° orientations. A gain of 18 dB was obtained for a passband of 13 MHz. Possible cross relaxations at the working point were considered. The inversion coefficient was calculated by solving the rate equations in the presence of cross relaxation.