空心光束是一种重要的结构光, 是光场调控研究领域的热点之一。拉盖尔-高斯光束是一种典型的空心光束, 因其螺旋状相位且携带轨道角动量, 因而也被称为涡旋光。涡旋光在光通信、量子纠缠和超分辨成像等领域有着极高的应用价值。本研究以全固态两镜凹平腔 Nd: YVO4 激光器作为实验平台, 通过在输出平面镜上制造点缺陷, 达到抑制低阶高斯模式起振, 从而获得高阶拉盖尔-高斯涡旋激光输出的效果。在连续波情况下, 最高获得了 16 阶涡旋激光输出; 在吸收功率为 3.3 W 时, 获得最高功率为 280 mW, 激光斜效率为 18.6%。进一步通过在谐振腔中插入 Cr:YAG 可饱和吸收体, 首次演示了具有正反手性的拉盖尔-高斯同时被动调 Q 脉冲激光, 稳定输出的最短脉冲宽度约为 232 ns, 相应的脉冲重复频率约为 229.1 kHz。本研究表明点缺陷镜是一种稳定可靠的直接产生高阶涡旋光的手段, 并且可以与被动调 Q 等固体激光技术结合产生不同运转方式的空间结构光束。

Hollow beam is an important structured light and also one of the hot research topics in the field of light field manipulation. As a typical hollow beam, Laguerre-Gaussian beam is also named vortex beam because of its helical phase. Moreover, because of carrying orbital angular momentum, vortex beam is tremendously valuable in optical communication, quantum entanglement and super-resolution imaging. In this work, based on the all-solid-state two-mirror concave-plane Nd:YVO4 laser experimental platform,the continuous-wave 16th-order vortex laser is obtained by fabricating some spot defects onto the output coupler to suppress the low-order Gaussian mode and force the operation of high-order Laguerre-Gaussian vortex laser. A maximum output power of 280 mW is achieved with a slope efficiency of 18.6% at an absorbed power of 3.3 W. Furthermore, a passive Q-switched high-order Laguerre-Gaussian laser with positive and negative handedness is demonstrated for the first time by inserting a Cr:YAG crystal into the laser cavity as a saturable absorber, and the shortest pulse width of the pulsed laser is 232 ns at a repetition rate of 229.1 kHz. The research indicates that spot defect mirror is a stable and reliable measures for direct generation of high-order vortex lasers. Moreover, it can be combined with other solid-state laser technology such as passive Q switching to produce spatially structured light operating at different regimes.