Abstract

Tunable and ultra-narrow linewidth visible sources are mandatory instruments for high-resolution spectroscopy or quantum information processing applications using rare-earth ions embedded in solid-state matrices. Optical Parametric Oscillators (OPOs) are an especially promising approach toward this goal because of their wide tuning range and good frequency stability. Indeed, in recent years, the increased availability of novel nonlinear materials and high-power solid-state single-frequency pump sources has led to great advances in the development of CW singly resonant optical parametric oscillators (SROPOs). In a previous work, we successfully used the recently developed periodically poled near stoichiometric LiTaO₃ (PPSLT) to build a cw SROPO emitting 100 mW in the red and pumped by a commercial green laser [1]. However, the output power of this system was limited by its high threshold and by the onset of thermal effect in the nonlinear crystal due to the large intracavity power at the visible wavelength. Another way to reach visible wavelengths consists in building an OPO emitting in the near-infrared and frequency doubling the idler in a second resonant cavity [2]. It is also possible to double or upconvert the infrared light resonating inside the OPO cavity. The configuration of internal frequency doubling is potentially more efficient because of the high intensity of the resonating beam. We have chosen to intracavity frequency double the idler resonating inside the OPO cavity. This architecture takes advantage of the fact that the jitter of pump laser can be absorbed by the wavelength which is non resonant in the cavity [1] and of the high near-infrared power that can be obtained from SROPOs based on PPSLT [3, 4].

© 2009 IEEE