Radio-frequency clock delivery via free-space frequency comb transmission

Abstract

We characterize the instability of an rf clock signal caused by free-space transmission of a frequency comb (FC) under typical laboratory conditions. The phase-noise spectra show the involvement of multiple random processes. For a 10 m transmission, the rms timing jitter integrated over 1-105 Hz is 95 fs, and the root Allan variance over 1 s is 4 × 10-13. The measured Allan variance has a τ-1 behavior and an excellent agreement with the phase noise measurement. These results indicate the feasibility of FC-based free-space rf clock distribution over short distances. © 2009 Optical Society of America.