GROUP-VELOCITY MISMATCH COMPENSATION IN CONTINUOUS-WAVE LASERS MODE-LOCKED BY 2ND-ORDER NONLINEARITIES

A group-velocity mismatch compensation technique has been applied to c w Nd:YAG and Nd:YLF lasers mode locked by use of the nonlinear reflect ivity or the nonlinear phase shift that arises from the intracavity pa rametric interaction of a pulse with its second harmonic. An intracavi ty birefringent plate, which delays the fundamental wavelength pulse w ith respect to the second-harmonic pulse, compensates for the opposite effect that arises in the second-harmonic crystal. Compensation reduc es the pulse duration by a factor of 2 and allows pulses of 5.1 and 5. 9 ps to be obtained from Nd:YLF and Nd:YAG lasers, respectively. (C) 1 995 Optical Society of America