title: Supercontinuum-based 10-GHz flat-topped optical frequency comb generation.
abstract: The generation of high-repetition-rate optical frequency combs with an ultra-broad, coherent and smooth spectrum is important for many applications in optical communications, radio-frequency photonics and optical arbitrary waveform generation. Usually, nonlinear broadening techniques of comb-based sources do not provide the required flatness over the whole available bandwidth. Here we present a 10-GHz ultra-broadband flat-topped optical frequency comb (> 3.64-THz or 28 nm bandwidth with ~365 spectral lines within 3.5-dB power variation) covering the entire C-band. The key enabling point is the development of a pre-shaping-free directly generated Gaussian comb-based 10-GHz pulse train to seed a highly nonlinear fiber with normal dispersion profile. The combination of the temporal characteristics of the seed pulses with the nonlinear device allows the pulses to enter into the optical wave-breaking regime, thus achieving a smooth flat-topped comb spectral envelope. To further illustrate the high spectral coherence of the comb, we demonstrate high-quality pedestal-free short pulse compression to the transform-limited duration.
authors.affiliation: School of Electrical and Computer Engineering, Purdue University, 465 Northwestern Avenue, West Lafayette, Indiana 47907, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Wu
authors.forename: Victor
authors.initials: V
authors.lastname: Torres-Company
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Leaird
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Weiner