National length standard supporting high-capacity optical fiber communication systems

— Development of fiber-based optical frequency combs—

Abstract

Optical frequency comb is a collection of laser modes with equal frequency intervals in the visible to near-infrared regions that enables direct comparison of optical frequencies with the microwave atomic frequency standards. Traditional solid state laser-based frequency comb systems were large, expensive and very difficult to operate for long periods of time during experiments. From the early stage of development, we proposed fiber lasers as a feasible means for achieving a reliable frequency comb. After we succeeded in developing an in-house fiber-based frequency comb at AIST, we made further advances, including calibration of optical telecommunication band, establishment of national standards of length, and development of a narrow-linewidth comb for optical lattice clocks.