Optical length metrology with extreme precision using fully controlled fiber-based frequency combs

Optical frequency comb can be used as a tool for high-precision and versatile control of properties of light wave as an "optical synthesizer". It provides powerful tools not only in frequency metrology as "ultraprecise frequency ruler" but also in broad area since light wave can be used to its full extent with an extremely wide dynamic range. In this paper, ultrahigh-precision length metrology using fiber-based optical frequency combs are presented. By precisely controlling the frequency and phase of the combs, two-color interferometry for self-correction of air refractive index with ultra-high accuracy exceeding the empirical equation is demonstrated.