Abstract

Output fluctuations of cw pumped Nd:YAG lasers have been extensively studied and are generally well understood [1]. In diode pumped unpolarised single longitudinal mode Nd:YAG lasers the RF power spectrum, shown in figure (1), typically has a relaxation oscillation peak around 30-200 kHz depending on the pump power and cavity parameters. At slightly higher frequencies (typically 100 kHz-10 MHz) another peak occurs [2], This peak is only detected when no polarisation controlling elements are present in the laser cavity, and arises because the 2 orthogonal polarised modes occur at slightly different frequencies. This frequency difference is due to thermal or stress birefringence present in the laser crystal as well as birefringence in the dielectric coatings on the crystal and output coupler.

© 1996 Optical Society of America