Optical frequency comb systems have received much attention in recent years due to their
enormous potential in optical frequency metrology and optical frequency synthesis
applications. The expected transition to optical time standards, attosecond lasers and
optical electron accelerators will all rely on the availability of rugged and stable
frequency comb lasers, combining superior performance with utility. Fiber laser based
frequency combs have a number of advantages over their Ti:sapphire cousins in that they
are more compact, are capable of turnkey, long-term operation with power consumption,
are compatible with existing fiber optics, and cover the telecommunication window. The
first fiber-frequency comb systems showed excellent long-term performance but the short
term performance was inferior to Ti:sapphire combs due to excess noise contribution.
However, recently it was shown that the linewidth of the individual comb limes of a fiber
frequency comb can reach the sub-Hertz level and fiber frequency combs are now
approaching the performance of Ti:sapphire based systems.