Investigation into the thermal effects of a Nd:YVO4 crystal at 1342 nm using the bistability-like output characteristics

Abstract

The influence of energy-transfer upconversion (ETU) and excited stimulated absorption (ESA) on the thermal effects of a Nd:YVO4 crystal was investigated in this paper. A stable continuous-wave (CW) single-frequency and intracavity frequency-doubled dual-wavelength 1342/671 nm laser was built, and the output power was manipulated by changing the transmissions of the output coupler. When the output coupler coated with a partial transmission film of 0.5% at 1342 nm was replaced by that of 8% at 1342 nm, the maximum output powers of the 671 nm and 1342 nm lasers ranged from 3.35 W and 1.08 W to 0.43 W and 6.35 W, respectively. By accurately measuring the threshold pump power as the incident pump power increased, a thermal loading of 6.8% caused by the ETU was successfully determined, which was the same for both output couplers. However, the thermal loading caused by the ESA had to be determined by measuring the threshold as the incident pump power decreased, and the measured thermal loading caused by the ESA was 14.03% for the output coupler with a transmission of 0.5%, which was larger than that of 9.13% for the transmission of 8% at 1342 nm. The measured results depicted that the thermal loadings caused by the ETU and ESA depended on the pump power and intracavity power of the 1342 nm laser, respectively. This technique for determining the thermal loadings of the Nd:YVO4 at 1342 nm using the bistability-like output characteristics is a good method of evaluating the thermal loadings and thermal lens effects of other laser crystals.