Probing coherence in microcavity frequency combs via optical pulse shaping

Fahmida Ferdous, Purdue University
Houxun Miao, National Institute of Standards & Technology (NIST); University of Maryland College Park
Pei-Hsun Wang, Purdue University
Daniel E. Leaird, Purdue University
Kartik Srinivasan, National Institute of Standards & Technology (NIST)
Lei Chen, National Institute of Standards & Technology (NIST)
Vladimir Aksyuk, National Institute of Standards & Technology (NIST)
Andrew M. Weiner, Birck Nanotechnology Center, Purdue University

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. (C) 2012 Optical Society of America

Discipline(s)

Nanoscience and Nanotechnology