We discuss experimental and theoretical aspects of a low-noise fiber-laser frequency comb, including the experimental configuration and the major contributions to the frequency noise and linewidth of the individual comb modes. Intracavity noise sources acting on the mode-locked laser determine the free-running comb linewidth and include environmental changes, pump noise, and amplified spontaneous emission (ASE). Extracavity noise sources acting outside of the laser typically determine the signal-to-noise ratio on the comb lines and include environmental effects, shot noise, and noise generated during supercontinuum generation. Feedback strongly suppresses these intracavity noise contributions, yielding a system that operates with comb linewidths and timing jitter below the quantum limit set by the intracavity ASE. Finally, we discuss correlations in the residual noise across a phase-locked comb.
© 2007 Optical Society of America
Ultrafast Fiber Lasers
Original Manuscript: November 2, 2006
Manuscript Accepted: December 19, 2006
Published: July 19, 2007
Nathan R. Newbury and William C. Swann, "Low-noise fiber-laser frequency combs (Invited)," J. Opt. Soc. Am. B 24, 1756-1770 (2007)