Continuous-wave, singly-resonant optical parametric oscillator based on periodically poled RbTiOAsC4

Abstract

The advent of periodically poled nonlinear materials offering high deff and the flexibility of grating-engineered phase-matching has had a broad impact in the field of nonlinear optics. In particular, the development of periodically poled (PP) LiNbO3 (PPLN) has placed the once prohibitively high oscillation thresholds of externally pumped singly-resonant optical parametric oscillators (OPOs) within the domain of conventional watt-level laser pump sources [1]. To reach oscillation threshold however, these devices need relatively long interaction lengths; when coupled with small crystal apertures and thermal lensing problems in PPLN these criteria can become limiting factors for high power operation. Intracavity cw OPOs have recently offered an alternitive solution for efficiently generating high-power, narrow-linewidth tunable cw radiation in the near-infrared [2]. The intracavity approach is uniquely placed to take advantage of smaller interaction lengths and lower d eff of recently developed periodically poled (PP) nonlinear materials such as PP-KTiOPO4 (PPKTP) and PP-RbTiOAsO4 (PPRTA). Combined with a static pump tuned geometry and room-temperature operation, intracavity SROs offer a versatile approach for generating cw laser radiation from these new quasi-phase-matched nonlinear materials. Here we outline the performance characteristics of a Ti:sapphire (TIS) pumped cw intracavity singly-resonant optical parametric oscillator (SRO) based on a 4.5-mm-long PPRTA crystal. To our knowledge, this is the first report of a cw OPO based on PPRTA.