The Noise Characteristics Of All Solid-state Blue Laser

The noise proprieties of CW intracavity doubling-frequency blue laser were studied in theory and experiments. The theory of the rate equations of intracavity doubling-frequency multi-longitudinal mode was applied to the quasi-three level blue lasers. The noise cases of single-longitudinal mode, two modes and more than two modes were analyzed. The stability output second harmonic generation (SHG) experiment results of single-longitudinal mode and multi-longitudinal mode with long cavity were explained reasonably with these rate equations. The high polarization of fundamental wave in the isotropic laser media Nd:YAG with type-I critical phase-matching LBO was studied with the rate equations including polarization of fundamental light. Using the polarization function of LBO, a quartz full-wave plate was introduced into the cavity, a kind of birefringent filter by considering the combination of the polarization function of the type-I critical phase-matching doubling frequency crystal LBO and the quartz whole-wave plate was constructed. The blue laser noise was depressed by selecting single-longitudinal mode. The stable operation of LD pumped Nd:YAG/LBO was obtained. When the pumping power was 1.2W, 25mW blue laser for single-longitudinal mode was obtained . The power stability of the laser was better than 5%, rms%(10Hz~50kHz) noise is less than 0.3%, the beam quality is less than 1.2, the coherent length is greater than 5m, thus the width of frequency band width is about 60MHz, the corresponding spectrum width is 0.00005nm.