Acoustooptic mode-locker frequency doubler

Means to simultaneously mode-lock and frequency double the output of a laser including a laser cavity defined by a pair of spaced reflector members arranged in optical communication and means for establishing a lasing condition between said spaced reflector members, the improvement comprising a crystal member positioned in the laser cavity in optical communication between the spaced reflectors, said crystal having an axis oriented at the Bragg angle with respect to the optical axis of the laser, said crystal member having non-linear characteristics at the frequency of the laser so as to double the frequency of laser energy passing therethrough, and means to excite the crystal member at a frequency equal to one-half of the axial mode spacing (c/2l) for the laser cavity to establish an acoustooptical standing wave therein which produces loss modulation at a frequency of (c/2l).

Apparatus for producing a mode-locked laser beam having a frequency that is the second harmonic of the fundamental laser frequency comprising a laser oscillator including a laser medium and spaced mirrors defining a laser-resonant cavity of predetermined length determinative of the fundamental frequency of the laser beam, and a single acoustooptic crystal disposed within said cavity for simultaneously mode-locking said beam and for interacting with the latter to produce the optical second harmonic thereof, said crystal having an axis oriented at the Bragg angle with respect to the optical axis of the laser, and means for modulating said crystal including means to establish an acoustic standing wave in the crystal, said last named means including a crystal transducer attached to the crystal, a source of RF energy, and a transmission line coupling the RF source to the transducer to produce acoustooptical standing waves in the crystal at a frequency equal to one-half of the axial mode spacing (c/2l) for the resonant cavity which operates to loss modulate the laser beam.