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All-fiber frequency comb at 2 µm providing 1.4-cycle pulses



Sida Xing, Abijith S. Kowligy, Daniel Lesko, Alexander Lind, Scott Diddams


We report an all-fiber approach to generating sub-2-cycle pulses at 2 µm and a corresponding octave-spanning optical frequency comb. Our configuration leverages mature erbium:fiber laser technology at 1.5 µm to provide a seed pulse for a thulium-doped fiber amplifier that outputs 330 mW average power at a 100 MHz repetition rate. Following amplification, nonlinear self-compression in fiber decreases the pulse duration to 9.5 fs, or 1.4 optical cycles. The spectrum of the ultrashort pulse spans from 1 to beyond 2.4 µm and enables direct measurement of the carrier-envelope offset frequency. Our approach employs only commercially available fiber components, resulting in a design that is easy to reproduce in the larger community. As such, this system should be useful as a robust frequency comb source in the near-infrared or as a pump source to generate mid-infrared frequency combs.
Optics Letters


Frequency Comb, Ultrafast Laser


Xing, S. , Kowligy, A. , Lesko, D. , Lind, A. and Diddams, S. (2020), All-fiber frequency comb at 2 µm providing 1.4-cycle pulses, Optics Letters, [online], (Accessed April 19, 2024)
Created May 1, 2020, Updated March 25, 2024