Multi-branch Fiber Frequency Comb for Precision Frequency Measurement of Molecular Transitions

SummaryPrecision spectrum measurement is one of the main applications of optical frequency combs. In this paper, we demonstrate a multi-branch optical frequency comb based on an erbium-doped-fiber femtosecond laser with a polarization-maintaining ‘9’ cavity. The comb includes five output ports with the target wavelengths including 1083 nm, 1380 nm, 1637 nm, 1064 nm and 1750 nm. The in-loop stabilities of the repetition rate and carrier-envelope-offset frequency are 2.9×10
⁻¹³
and 1.7×10
⁻¹⁸
at 1 second integration time respectively, which meets the sub-kilo hertz cavity ring-down spectroscopy (CRDS) measurements requirements.