Alignment-insensitive end-pumped continuous-wave crossed-Porro prism Ho³⁺:YAG laser

Abstract

A continuous-wave crossed-Porro prism Ho3+:YAG laser is presented and compared with a corresponding mirror resonator. A maximum output power of 30.7 W is reached with a slope efficiency of 67.4 % with respect to the absorbed pump power. The laser output beam shows a very good beam quality of better than M2 < 1.2 which clearly surpasses that of the mirror resonator. In terms of alignment sensitivity, the crossed-Porro prism resonator is superior to the mirror resonator due to the retro-reflective nature of the prisms in the axis around the apex.

14 W linear ZGP OPO pumped by a Q-switched Ho3+:YAG laser with a maximum energy of 2.2 mJ

“…This supports the statement that with introducing a suitable lens, an improvement in mode overlap is generated. 13 In the optimum configuration with the f = −0.08 m lens, a maximum output power of 14.1 W was measured corresponding to a pulse energy of 0.56 mJ. A beam quality factor M 2 of 2.1 and 3.3 was measured in the xand y-axis of the signal beam and 2.4 and 3.5 in the x-and y-axis of the idler beam.…”

“…On the other hand, it can be attributed to the increase in mode size when the resonator is lengthened or when a lens is included. 13 The influence of the diverging lens becomes even clearer when investigating the beam quality. Figure 4 shows exemplary beam quality measurements for the vertical beam axis of the signal beam.…”

Q-switched Ho3+:YAG Porro resonators with improved alignment stability

“…This instability is accompanied by losses in output power. 9 The following investigations are therefore carried out at lower powers where these instabilities do not yet occur. Beam quality measurements are conducted for both configurations by focusing the output beam with a planoconvex lens and measuring the beam diameter along the propagation direction with a camera.…”