Excess Phase Noise Characterization in Multifrequency Remote Clock Distribution Based on Femtosecond Frequency Combs

Applied Sciences

Changjun Hu¹  Ravi P. Gollapalli²  Lin Yang¹  Lingze Duan¹ 

[1] Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899, USA; E-Mail:;Department of Electrical and Computer Engineering, University of South Alabama, Mobile, AL 36688, USA; E-Mail:

关键词: clock distribution;    optical frequency comb;    multiheterodyne;    phase noise;    fiber optics;    free-space communication;   

DOI  :  10.3390/app5020077

来源: mdpi

【 摘 要 】

Remote distribution of optical frequency references, based on multifrequency sources such as femtosecond frequency combs, holds many advantages over its single-frequency counterpart. However, characterizing the excess noise caused by the transmission links or external perturbations in a multifrequency scheme posts new challenges. We have experimentally demonstrated direct measurement of excess phase noise spectrum in both free-space and fiber-optic transfer of a frequency comb using a multiheterodyne technique. In fiber-optic distribution, we focused on the excess phase noise under a single-tone acoustic perturbation. Increased overall noise power and a change of phase noise spectrum have been observed. In free-space distribution, a fractional instability of 3 × 10⁻¹⁴ at 1 s was observed for a 60 m outdoor atmospheric transmission, and large phase modulation due to air fluctuations causes a sizable line broadening.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.