Investigation On Watt Level CW Frequency-stabilized Nd～(3+):YAP/KTP Lasers With Dual Wavelength Outputs

A continuous laser-diode end-pumped Nd3+:YAP/KTP laser with dual wavelength outputs at 0.54um and 1.08um has been achieved.Laser diode is the most efficient pumping source for Solid-State-Lasers. The heat from quantum defect and pumping beams except absorption spectrum is decreasing. But the absorption efficiency, stokes efficiency, quantum efficiency and the superposition efficiency between pump mode and cavity mode is less than one respectively, so the local heat absorption of the crystal is quite strong, and its thermal effect is quite obvious. Two measures were taken. The cooler and temperature controller of Nd:YAP rod are improved and the lower dopant concentration of the Nd:YAP (0. 6 at.%) is chosen, thus the thermal effect of the laser rod is decreased.Four-mirror ring cavity and six-mirror ring cavity has its advantages and shortcomings, respectively. The former has compact structure;,little cavity loss, higher coupling efficiency, and higher superposition efficiency. But there is no enough room for other devices. The latter overcome this problem, but the diffraction loss and mirror loss is increased. It is difficult to get high power output. So we use five-mirror ring cavity. After calculating and comparing the waist-sizes of the fundamental wave, and the astigmatism effect caused by different incident angles to the concave mirrors, we choose the curvature radii of the concave mirrors as 100 millimeter and the incident angles of infrared light which are less than 3 degree.Under a pump power of 10W, the simultaneously obtained output powers for the second-harmonic wave and the fundamental wave are 1.02W and 700m W with the intensity fluctuations less than +0. 65% and +0. 5%, respectively. With the frequency-stabilizing servo system on, the frequency stabilities for 0.54um and 1.08um wavelengths are better than ±484KHz and ±240KHz, respectively.