Solid-state laser radiation noise

Calculations were made of the transfer functions and amplitude fluctuations of a multimode YAG:Nd³⁺ laser with pump modulation and Q switching. By allowing for the influence of energy redistribution between the modes on their spatial competition, it was possible to identify some characteristics of the transfer function and of the spectral distribution of the noise at low frequencies with unequal mode intensities. A YAG:Nd³⁺ laser with an output power of 2 W in the TEM₀₀ mode and a noise level of 0.1% in the frequency range 0.5 Hz–500 kHz was built. It was shown that this noise level is close to the limit of passive stability of a laser pumped by a krypton arc flashlamp.