Widely tunable cavity-enhanced frequency combs

We describe the cavity enhancement of frequency combs over a wide tuning range of 450–700 nm (${ \gt }7900\;{{\rm cm}^{ - 1}} $>7900cm−1), covering nearly the entire visible spectrum. Tunable visible frequency combs from a synchronously pumped optical parametric oscillator are coupled into a four-mirror, dispersion-managed cavity with a finesse of 600–1400. An intracavity absorption path length enhancement greater than 190 is obtained over the entire tuning range, while preserving intracavity spectral bandwidths capable of supporting sub-200 fs pulse durations. These tunable cavity-enhanced frequency combs can find many applications in nonlinear optics and spectroscopy.