Analysis of the carrier-envelope phase noise of passively phase-locked Er:Fiber frequency combs up to the Nyquist frequency

We study the carrier-envelope phase noise of an Er:fiber frequency comb which is passively phase-locked at the full repetition rate of 100 MHz. A novel characterization method determines an out-of-loop phase jitter of only 250 mrad when integrated over 12 orders of magnitude: from 50 μHz up to the Nyquist frequency.