Optical Frequency Comb

Abstract

Optical Frequency comb has become a ruler of light nowadays for standard of length. A notable synergy among existing technologies occurs for stabilization of laser frequencies in the rule of the frequency spectrum, called “comb” of sharp and equidistance lines. With such an optical frequency comb, the exact frequencies of the entire comb lines are measured, revolutionizing the measurement of length in more precise way and realizing SI Unit Meter with better accuracy. This capability has transformed optical frequency metrology for better precision. The pulse from Optical Frequency Comb can produce a temporal coherence interference fringe pattern, which can be used as a practical method for realization of SI Unit Meter. The emergence of the optical frequency comb know-how, in 2005 (Nobel Prize in Physics) has eliminated the demand for knotty frequency chains. By straight connecting, the second, using frequency standards of Cs, or Rb, by optical frequency comb, we can set up a novel technique for realistic realization of length of the SI unit Meter (Primary Standard). By means of stabilizing and characterizing the two different constraints – the carrier offset frequency f0 and the repetition frequency fr of the optical comb is effectively used for practical realization of SI unit “Metre.” The accuracy in the measurement of the length increased by many order using optical frequency comb, i.e., 2 × 10−13 instead 10−7 by using Iodine stabilized He-Ne Laser. In this chapter we present a review of optical frequency comb as a new quantum standard for realization of SI unit “Metre.” A brief review of determining the absolute value of laser frequency in calibration using an optical frequency comb is illustrated here in this chapter.In this chapter we reviewed the optical frequency comb as a novel tool for realization of SI unit Meter for length metrology. Particularly, an iodine-stabilized He-Ne laser incessantly sweeps to a steady optical frequency comb, where its output frequency is modulated over a wide spectrum to determine the exact frequency using optical interferometry. This method established a practical method to measure length in terms of SI unit meter with minimum uncertainty, which is straight traceable to SI unit second (Time Standard).