Linewidth narrowing of high power diode lasers for alkali vapor laser

To avoid the smile effect, which seriously restricts the linewidth narrowing of high power diode laser for alkali vapor laser, a 780 nm single-broad-area high power diode laser was studied. An output beam with 11.5 W power, 61% external cavity efficiency was obtained with the optimized Littman configuration, when the laser run freely at 19 W. When the beam transmitted through a 25 cm long, 110 ℃ Rb vapor cell with 80 kPa ethane, 96.7% power was absorbed. The theory calculation supports the 0.03 nm linewidth (15 GHz spectral width) derived from experimental results.