Optical frequency combs referred to each other

摘要

Embodiments herein provide for an optical frequency reference including a fine optical frequency comb and a coarse optical frequency comb. The fine comb has a first tooth and a frequency spacing (FCS) between teeth that is locked to a fractional or integer multiple of a radio frequency reference. The coarse comb has a second tooth that is locked to the first tooth and a frequency spacing (CCS) between teeth that is locked to an integer multiple of the FCS. An absolute optical frequency of at least one tooth of the coarse optical frequency comb is set.