CHARACTERISTICS OF A NONCRITICALLY PHASEMATCHED TI-SAPPHIRE PUMPED FEMTOSECOND OPTICAL PARAMETRIC OSCILLATOR

The operating characteristics of a singly-resonant femtosecond optical parametric oscillator (OPO) based on a noncritically phasematched geometry in KTP are described. The parametric oscillator is synchronously pumped by a self-modelocked Ti:sapphire laser and is operated in a standing-wave cavity configuration. With extracavity dispersion compensation, chirped pulses of 90 fs are generated, whilst shorter transform-limited pulses of 40 fs are generated with intracavity dispersion compensation. A numerical model of the effects of self-phase-modulation in the OPO has been developed and gives results which are in good qualitative agreement with experiment. Experimental results are presented relating to non-phasematched processes in the OPO, and the implications for the development of a tunable femtosecond source in the blue spectral region are discussed. A characterisation of the amplitude and phase noise of the OPO has also been performed, and provides insight into the important physical processes governing the stability of OPO operation.