27-W average output power with 1.2*DL beam quality from a single-rod Nd:YAG laser with phase-conjugating SBS mirror

The beam quality of a single-rod Nd:YAG laser with large mode volume was improved almost up to the diffraction limit by using a phase-conjugating mirror (PCM) based on stimulated Brillouin scattering (SBS). A new resonator design was used with sulfur hexafluoride as the SBS medium. The laser is Q-switched by the nonlinear reflectivity of the PCM. The stable fundamental mode operation and high efficiency via large mode volume was guaranteed by the combination of a highly selective aperture setup and the SBS mirror. The system exhibits a temporal burst structure of up to 50 Hz and a repetition rate of 11 kHz within the burst. The single Q-switch pulse showed a width of 42 ns. The energy, width, and repetition rate of the Q-switch pulses within the burst can be adjusted by varying the parameters of the laser system.