An 80-W Laser Diode Array with 0.1 nm Linewidth for Rubidium Vapor Laser Pumping

The spectral linewidth of a 64-emitter laser-diode array is effectively suppressed by using a volume Bragg grating (VBG) based external cavity. At a maximal driven current of 90 A, the device produces a cw output of 80W with 1.2 W/A slope efficiency and 0.1 nm spectral linewidth (FWHM) centered at 780 nm. The power extraction efficiency reaches 90% as compared with the free running case. The central wavelength of the narrowed spectrum is tuned over a 0.3 nm range by adjusting the VBG's temperature. The absorption of 45% laser radiation by a 5-mm-long rubidium vapor cell with 150 Torr ethane and 450 Torr helium at 383 K is demonstrated.