Narrow-linewidth frequency transfer from 698 nm to 1542 nm based on Er-doped fiber optical frequency comb

Abstract

Narrow-linewidth optical frequency combs are widely used in optical clock frequency comparisons. This paper reports a narrow-linewidth Er-doped fiber optical frequency comb which can achieve the transmission of narrow-linewidth optical frequencies from 698 nm to 1542 nm. An electro-optic modulator is used as a high servo bandwidth component in the narrow-linewidth optical frequency comb, realizing the fast phase-locking of the comb teeth to a narrow-linewidth laser with a servo bandwidth of 236 kHz. With the single-point frequency-doubling method, the optical frequency comb can realize an output at a wavelength of 698 nm. When the comb teeth are phase-locked to a narrow-linewidth 698 nm laser, the integrated phase noise is 0.68 rad with an integration range from 5 MHz to 1 Hz, and the linewidth is less than 2.38 Hz at 1542 nm. This indicates that the narrow-linewidth characteristic of the optical frequency comb is transmitted from 698 nm to 1542 nm.