We present a semimonolithic frequency-doubler from 1080 to 540 nm with 80% doubling efficiency and up to 849-mW output power of green light. A frequency-stabilized laser diode (LD) pumped continuous wave (CW) Nd:YAP laser is used as the pump source of the doubler consisting of an α-cut KTP crystal and an input mirror. The frequency stabilities of the output second harmonic wave are better than ±246 kHz and ±2.3 MHz in 1 and 30 minutes, respectively, and the intensity fluctuation is less than ±0.65%.
The frequency stability of an all-solid-state Nd:YVO4 laser is significantly improved by means of a specially designed Fabry-Perot (F-P) interferometer used for the frequency standard in the frequency-stabilizing system. The ten.peraturo of the F-P cavity is accurately controlled by a set of thermoelectric cooler (TEC) modules attached on th dy of the cavity and the electronic feedback circuit. We find that the long-term unidirectional frequency shift of the output laser, resulting from the slow increase of the cavity length under the effect of the temperature integration on the cavity body, is essentially eliminated. The frequency stability of the output laser with the power of 530 mW is better than ±200 kHz in 1 minute and ±2.3 MHz iu 40 minutes, respectively. The fluctuation of output power is smaller than ±0.5% over one hour.
