Observation of mode locking in a synchronously pumped Nd:YAG laser

We report on the mode-locking behavior of a 1.06-microm Nd:YAG ring oscillator synchronously pumped by a 76-MHz, 20-psec dye laser at 0.59 microm with an average power of 600 mW. Gain modulation is based on relaxation from the pump band to the upper laser level with a time constant (minimum gain modulation time) of 470 psec; stable modelocked operation is achieved with a gain modulation of only 10(-4). Preliminary results give a minimum pulse width of 140 psec and suggest a novel way of mode locking rare-earth waveguide lasers.