Ultrastable operation and continuous frequency tuning of a doubly resonant parametric oscillator

Summary form only given. We have demonstrated that both mode-hop-free operation over unlimited time and smooth frequency tuning over a substantial range is possible with a cw doubly resonant optical parametric oscillator (OPO). Taking into account that signal/idler linewidths are known to be comparable to the pump linewidth, the present results establish that the doubly resonant oscillator (DRO), used in conjunction with a wavemeter, has all the features necessary to become a practical source for spectroscopy.