A novel ring laser resonator of linear geometry with twin off-axially cut Nd:YVO₄

A ring laser resonator is realized in a compact linear configuration with a twin-Nd:YVO₄ device formed by a pair of off-axially cut Nd:YVO₄ crystals, which are closely packed with their optical axes being rotated 90° from each other. In a linear resonator with a twin-Nd:YVO₄ device sandwiched by two intra-cavity quarter-wave plates, laser beams can circulate in the twin-Nd:YVO₄ device. Due to spatial walk-off resulted from birefringence within the twin-Nd:YVO₄ device, the spatial modulation of laser gain is eliminated. A stable IR output of 51 mW at 1064 nm is obtained with a pump power of 581 mW at 809 nm. The threshold pump power is 207 mW, and laser slope efficiency is 13.6%. Stable green light can also be obtained by temperature-controlling the intra-cavity nonlinear crystal KTP as a quarter-wave plate to replace one of the intra-cavity quarter-wave plates.