Fiber laser-based frequency combs with high relative frequency stability

We describe our current low-noise fiber-laser frequency comb and present measurements of its residual instability. Through a comparison with a Ti: Sapphire frequency comb, we measure residual fractional frequency instabilities (Allan deviation) of -6times10
^-17
at 1 second and -1.3times10
^-18
at 1000 seconds. This stability demonstrates that the performance of a fiber frequency comb can rival that of current Ti: sapphire frequency combs.