Diffraction-limited single frequency 780 nm lasers are required to cool and manipulate rubidium atoms for various quantum applications. For advanced quantum technology applications like large scale atom interferometers, high power (several tens watts and more) 780 nm laser is required. Several effords had been reported to produce over ten watts 780 nm laser by frequency doubling of a 1560 nm Er fiber amplifier.
We have made our contribution recently based on our knowledge in high power Raman fiber laser and high efficiency freqeuncy doubling. A home-made a high power 1480 nm Raman fiber laser is used it to core-pump a Er fiber amplifier directly into the up level of the laser transition. It allows high power and high efficiency amplification of the 1560 nm single frequency laser before the onset of stimulated Brillouin scattering. With the 50 W 1560 nm output, a 21.2 W continuous-wave single frequency 780 nm laser was achieved by utilizing single-pass frequency doubling in a MgO:PPLN crystal.
The result is reported recently on Optics Letters.
J. Dong, X. Zeng, S. Cui, J. Zhou, and Y. Feng, “More than 20 W fiber-based continuous-wave single frequency laser at 780 nm,” Opt. Express 27(24), 35362 (2019).
The work is an excellent demonstration of our combined experience on high power Raman fiber lasers, high power single frequency fiber amplifiers, and high efficiency second harmonic generation.