Absolute optical frequency measurement of stabilized lasers using an Er-doped fiber femtosecond laser comb

As a bridge connecting microwave frequency and optical frequency, the femtosecond optical frequency comb plays an important role in absolute optical frequency measurement. Compared with the traditional Ti: sapphire femtosecond optical frequency comb, with the advantages of compact structure, strong anti-interference ability and low cost, the fiber femtosecond optical frequency comb has a tendency to replace Ti: sapphire femtosecond optical frequency comb in some applications. Especially, due to the spectrum can be extended to visible light, fiber femtosecond optical frequency comb has a wider application prospect in the field of absolute optical frequency measurement. A frequency measurement system is set up based on an Er-doped femtosecond fiber comb. A hydrogen clock is used as a frequency standard, the optical frequency comb is traced to the hydrogen clock. Then an absolute frequency measurement of an acetylene-stabilized laser is realized by using this highly stable optical frequency comb. In addition, a narrow spectrum with a central wavelength of 633nm is achieved by Raman shifts and frequency doubling. The frequency and stability of the 633nm wavelength secondary standard are measured by beating.