title: Bandwidth scaling and spectral flatness enhancement of optical frequency combs from phase-modulated continuous-wave lasers using cascaded four-wave mixing.
abstract: We introduce a new cascaded four-wave mixing technique that scales up the bandwidth of frequency combs generated by phase modulation of a continuous-wave (CW) laser while simultaneously enhancing the spectral flatness. As a result, we demonstrate a 10 GHz frequency comb with over 100 lines in a 10 dB bandwidth in which a record 75 lines are within a flatness of 1 dB. The cascaded four-wave mixing process increases the bandwidth of the initial comb generated by the modulation of a CW laser by a factor of five. The broadband comb has approximately quadratic spectral phase, which is compensated upon propagation in single-mode fiber, resulting in a 10 GHz train of 940 fs pulses.
authors.affiliation: Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA. supradeepa@ofsoptics.com
authors.forename: V R
authors.initials: VR
authors.lastname: Supradeepa
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Weiner