Two-frequency ruby maser

A description is given of a two-frequency ruby maser capable of amplification at frequencies of 1.3 and 9.4 GHz. The values of the inversion coefficients and gains at these frequencies are given. It is shown that the same configuration can be used to widen the maser band when the energy intervals 1–2 and 3–4 between the levels differ by the ESR line width. Possible applications of such amplifiers are indicated.