Continuously tunable single-frequency 455 nm blue laser for high-state excitation transition of cesium.

A continuously tunable high-power single-frequency 455 nm blue laser for high-state excitation transition 6S2↔7P2 of Cs atoms was presented in this Letter, which was implemented by an intracavity frequency-doubled Ti:sapphire laser with an LBO crystal. The highest output power of 1.0 W was attained under a pump power of 13.5 W with an optical conversion efficiency of 7.4%. The measured power stability in 3 h and beam quality were better than ±0.27% (peak-to-peak) and Mx2=1.58, My2=1.18, respectively. By continuously scanning the length of the resonator after locking the employed intracavity etalon to the oscillating longitudinal mode of the laser, the continuous tuning range of the 455 nm blue laser was up to 32 GHz and was mode hop free. Lastly, the whole saturation absorption spectrum of the higher state excitation transition 6S2(F=3)↔P2(F=2,3,4) and 6S2(F=4)↔7P2(F=3,4,5) of Cs133 was successfully observed in the experiment, which further verified the excellent performance of the 455 nm blue laser.