Wlodarczyk Krystian L, Thomson Ian J, Baker Howard J, Hall Denis R
School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, UK.
Appl Opt. 2012 Sep 10;51(26):6352-60. doi: 10.1364/ao.51.006352.
We report a new technique for the rapid fabrication of microstripe cylindrical and toroidal mirrors with a high ratio (>10) of the two principal radii of curvature (RoC(1)/RoC(2)), and demonstrate their effectiveness as mode-selecting resonator mirrors for high-power planar waveguide lasers. In this process, the larger radius of curvature (RoC(1)) is determined by the planar or cylindrical shape of the fused silica substrate selected for laser processing, whilst the other (RoC(2)) is produced by controlled CO(2) laser-induced vaporization of the glass. The narrow stripe mirror aperture is achieved by applying a set of partially overlapped laser scans, with the incident laser power, the number of laser scans, and their spacing being used to control the curvature produced by laser evaporation. In this work, a 1 mm diameter laser spot is used to produce grooves of cylindrical/toroidal shape with 240 μm width and 16 mm length. After high reflectance coating, these grooves are found to provide excellent mode selectivity as resonator mirrors for a 150 μm core Yb:YAG planar waveguide laser, producing high brightness output at more than 300 W. The results show clearly that the laser-generated microstripe mirrors can improve the optical performance of high-power planar waveguide lasers when applied in a low-loss mode-selective resonator configuration.
我们报道了一种快速制造微条纹圆柱面和 toroidal 面镜的新技术，其两个主曲率半径（RoC(1)/RoC(2)）的比率较高（>10），并展示了它们作为高功率平面波导激光器的模式选择谐振腔镜的有效性。在此过程中，较大的曲率半径（RoC(1)）由选择用于激光加工的熔融石英基板的平面或圆柱形状决定，而另一个（RoC(2)）则通过受控的 CO(2) 激光诱导玻璃汽化产生。窄条纹镜孔径是通过应用一组部分重叠的激光扫描实现的，入射激光功率、激光扫描次数及其间距用于控制激光蒸发产生的曲率。在这项工作中，使用直径 1 毫米的激光光斑来产生宽度为 240 微米、长度为 16 毫米的圆柱/ toroidal 形状的凹槽。经过高反射率涂层处理后，发现这些凹槽作为 150 微米芯径的 Yb:YAG 平面波导激光器的谐振腔镜具有出色的模式选择性，在超过 300 瓦的功率下产生高亮度输出。结果清楚地表明，激光产生的微条纹镜在应用于低损耗模式选择谐振腔配置时可以提高高功率平面波导激光器的光学性能。
