Frequency-Doubled,Single-Frequency Nd:YAG Laser.

摘要

The objective of the work reported herein is to achieve stable,single-frequency second harmonic power output from a Nd:YAG laser. Particular emphasis is placed on frequency and amplitude stability and on conversion efficiency. The experimental results of this program indicate that frequency and amplitude stable frequency-doubled operation of the single-frequency Nd:YAG laser can be achieved. Single-frequency operation is obtained by the use of a ring cavity containing a differential loss and frequency-doubled operation by the use of an intracavity 5cu mm barium sodium niobate crystal. The 1.06microns laser output is 3/4to 1 W and the maximum 0.53microns output is 140mW. Degradation of the crystal reduced this level to a repeatable 50to 100mW frequency stable to +or - 12MHz and amplitude stable to +or - 4percent over a number of minutes operating period. Thermal effects in the nonlinear crystal arising from absorption of the fundamental wavelength radiation were found to limit the amplitude and frequency stability of the laser output. The same effects distort the 0.53microns farfield beam profile and reduce the conversion efficiency. Techniques necessary to achieve stable frequency-doubled operation of the single-frequency Nd;YAG laser were established during this program. Further improvement in the stability and conversion efficiency depends on the availability of barium sodium niobate crystals with low absorption at 1.06microns. (Author)