Spectrum of relaxation frequencies of a multimode solid-state laser

The spectrum of relaxation frequencies of a YAG:Nd³⁺ laser is determined analytically for a partial filling of the resonator with an active medium. It is shown that the lowest relaxation frequency corresponds to periodic transfer of energy from one half of the spectrum to the other. The results of an experimental investigation of the spectrum of the power noise corresponding to one half of the emission spectrum confirmed the occurrence of fluctuations of this type with a frequency ≲1 kHz.