We demonstrate a mid-IR frequency comb centered at 3120 nm with 650-nm (20-THz) bandwidth at a comb-teeth spacing of 500 MHz. The generated comb is based on a compact ring-type synchronously pumped optical parametric oscillator (SPOPO) operating at degeneracy and pumped by a mode-locked Er-doped 1560 nm fiber laser at a repetition rate of 100 MHz. We achieve high-repetition rate by using a fractional-length cavity with a roundtrip length of 60 cm, which is one-fifth of the length dictated by conventional synchronous pumping.
© 2014 Optical Society of America
Original Manuscript: December 3, 2013
Manuscript Accepted: December 22, 2013
Published: February 10, 2014
Kirk A. Ingold, Alireza Marandi, Charles W. Rudy, Konstantin L. Vodopyanov, and Robert L. Byer, "Fractional-length sync-pumped degenerate optical parametric oscillator for 500-MHz 3-μm mid-infrared frequency comb generation," Opt. Lett. 39, 900-903 (2014)