A low phase noise high power Er-fiber frequency comb synchronized to the hydrogen maser clock by harmonic phase locking

We demonstrate a low phase noise all polarization-maintaining (PM) Er-fiber optical frequency comb (OFC) with noise, which is synchronized to the hydrogen maser clock (HMC) using 18th harmonic of repetition rate for tight locking. The instability locked carrier envelope offset 1.24 × 10 −18 @1 s, OFC −96 dBc/Hz at 1 Hz offset, and corresponding RMS timing jitter 62 fs (1 Hz–1 MHz). residual (200 MHz) 1.46 −14 normalized MHz −138 declines about −160 far-end, much lower than that HMC (−122 −156 far-end).