LD泵浦固体激光器基模振荡光的场分布噪音

The Base Mode′s Distribution Noises in LD Pumped Solid-state Laser

通过调整泵浦光直径 ,使得LD端面泵浦固体激光器的振荡光工作于基模 .在排除高阶横模的条件下 ,测量了由于热透镜的不稳定引起的光场场分布的噪音 .实验发现 ,基模振荡光的高斯半径、光束指向角都在波动 ,而且光斑存在畸变波动 .对一个未采取抑制措施的 2W连续LD端面泵浦Nd∶YAG固体激光器进行了测量 .结果表明 ,在总功率不变的情况下 ,激光束峰值点附近的光强波动达到 6.3% ;激光的高斯半径波动达到 5 .8% ;激光的指向角波动达到 0 .3mrad .

By adjusting the pumping beam′s radius to a small value, a laser diode end-pumped Nd:YAG laser has been controlled strictly to operate in the base mode. In such case, the distribution noises were studied, which showed the laser beam′s radius, direction and shape undulated continuously. The reason is the unsteady of the thermal lens. Undulations of the laser beam′s radius were related to the oscillations of the focus length, and the laser direction′s undulations were caused by the swinging motion of the thermal lens. The distorted changing shape of the beam was produced by the unsteady asymmetrical shape of the thermal lens.With 2 watts CW pump power and steady output power, the undulations of the laser′s intensity were observed as high as 6.3% near the beam center. After further analysis, undulations of beam′s radius were discovered as high as 5.8%, and the undulations of the laser direction were discovered near 0.3 mrad.