Rotating off-centered lens in SBS phase conjugation mirror for high-repetition-rate operation

A new method using a rotating off-centered lens is proposed to reduce the heat accumulation at the focal spot of a stimulated Brillouin scattering phase conjugation mirror at high-repetition-rate operation. Theoretical simulation of the beam intensity pattern at the focal point indicates there is less coma-aberration using a rotating off-centered focusing lens than with a rotating wedge and a conventional lens. The resultant SBS output parameters using this new method are substantially improved comparable to those of a non-rotating conventional method for high-repetition-rate operation, while the former operates quite well for higher power and the latter operates only for lower input power. High reflected energy and a good beam pattern are demonstrated using the proposed method in the present experimental conditions of 50 mJ at 1 kHz.