title: Probing coherence in microcavity frequency combs via optical pulse shaping.
abstract: Recent investigations of microcavity frequency combs based on cascaded four-wave mixing have revealed a link between the evolution of the optical spectrum and the observed temporal coherence. Here we study a silicon nitride microresonator for which the initial four-wave mixing sidebands are spaced by multiple free spectral ranges (FSRs) from the pump. Additional lines then fill in to yield a comb with single FSR spacing, resulting in partial coherence. By using a pulse shaper to select and manipulate the phase of various subsets of spectral lines, we are able to probe the structure of the coherence within the partially coherent comb. Our data demonstrate strong variation in the degree of mutual coherence between different groups of lines and provide support for a simple model of partially coherent comb formation.
authors.affiliation: School of Electrical and Computer Engineering, Purdue University, 465 Northwestern Avenue, West Lafayette, IN 47907-2035, USA. fferdous@purdue.edu
authors.forename: Fahmida
authors.initials: F
authors.lastname: Ferdous
authors.forename: Houxun
authors.initials: H
authors.lastname: Miao
authors.forename: Pei-Hsun
authors.initials: PH
authors.lastname: Wang
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Leaird
authors.forename: Kartik
authors.initials: K
authors.lastname: Srinivasan
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Vladimir
authors.initials: V
authors.lastname: Aksyuk
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Weiner