Quantum fluctuations of radiation in a ring Nd:YAG chip laser

We report theoretical and experimental investigation of intensity fluctuations in a travelling-wave ring Nd:YAG chip laser, caused by the noise of spontaneous emission. In accordance with theory and experiment, quantum intensity fluctuations in the laser under study decrease dramatically with increasing pump over the threshold. As a result of the research performed, the factor β is found, which determines the ratio of the rate of spontaneous emission into the generated mode to the total rate of spontaneous emission into all modes. The effect of the relaxation rate from the lower laser level on quantum fluctuations of the radiation intensity is found.