Simultaneous brightness enhancement and wavelength conversion to the eye-safe region in a high-power diamond Raman laser

Brightness enhancement in an external cavity diamond Raman laser designed for high power conversion of a neodymium (1064nm) laser to the eye-safe spectral region is reported. Using a multimode input beam pulsed at 36kHz pulse repetition frequency, 16.2W with 40% overall conversion efficiency was obtained at the second Stokes wavelength of 1485nm. The output beam had a quality factor of M2=1.17 +/- 0.08 which is a factor of 2.7 times lower than that of the input beam, resulting in a higher overall brightness. The output power, brightness, and brightness enhancement obtained represent significant advances in performance for Raman lasers as well as other competing kHz-pulsed eye-safe technologies.