Continuous-wave alexandrite thin-disk laser in multi-mode and fundamental-mode operation

We present investigations of a continuous-wave (CW) alexandrite thin-disk laser in both multi-mode and fundamental-mode operation. In multi-mode operation, the laser delivered a maximum average output power of 15 W with an optical efficiency of approximately 18%, at a central wavelength of 747 nm. The fundamental-mode average output power was 5.1 W, corresponding to an optical efficiency of approximately 7.5%. In this operation mode, the beam propagation factor was measured to be M 2 ≈ 1.01 with a spectral bandwidth of 7.4 nm full-width at half-maximum (FWHM). The results demonstrate stable operation, providing a foundation for further scaling of alexandrite thin-disk lasers.