Generation of ultraviolet (335-nm) light by intracavity frequency doubling from active mode-locking action of an external-cavity AlGaInP diode laser

An intracavity frequency-doubling scheme was merged with an actively mode-locked AlGaInP laser diode with an external cavity to provide efficient generation of 335-nm ultraviolet light. Intense pulses of <16ps were successfully generated inside the cavity at subgigahertz repetition frequencies. We applied those pulses to intracavity second-harmonic generation from a 5-mm-long LiIO(3) crystal, which resulted in average ultraviolet power of 70muW for an average fundamental power of 73 mW.