990 mW average power, 52% efficient, high-repetition-rate picosecond-pulse generation in the blue with BiB_3O_6

Efficient single-pass second-harmonic generation (SHG) of tunable high-repetition-rate picosecond pulses into the blue is reported in the nonlinear crystal BiB3O6. Using 2.4 ps fundamental pulses from a mode-locked Ti:sapphire laser at 76 MHz and a 10 mm crystal cut for type I (e + e --> o) phase matching in the optical yz plane, second-harmonic average powers as high as 990 mW with excellent stability have been generated at 52% conversion efficiency, and a tunable range of 370-450 nm is demonstrated. From measurements of single-pass SHG in the continuous-wave regime an effective nonlinear coefficient of 3.7 pm/V has been verified for BiB3O6, and direct comparison with beta-BaB2O4 confirms a SHG power enhancement of approximately 23% for the same crystal length. Autocorrelation measurements in a 200 microm crystal of beta-BaB2O4 result in durations of 2.8 ps for the second-harmonic blue pulses.