Novel Single-Frequency Nd:YAG Ring Laser by Reducing the Depolarization Loss

A principle study on reducing the depolarization loss in a single-frequency Nd:YAG ring laser by a novel ring resonator configuration is reported. In the resonator, one cavity mirror with 99.5% reflectivity at 1064 nm for 45-degree incident s-polarized light and about 75% transmissivity for 45-degree incident p-polarized light was employed. Besides, the transmissivity for the 45-degree incident p-polarized and s-polarized light for the output-couple mirror were 32% and 3.5%, respectively. The cavity mirror and the output-couple mirror were utilized as the polarizer to enforce the s-polarized beam unidirectionally operating in the resonator. 2.1 W single-frequency output at 1064 nm with elliptical polarization was obtained from this ring resonator. Compare with the existent Nd:YAG ring resonator, this novel resonator has a potential advantage in reducing depolarization loss and increasing the efficiency.