title: Harmonic mode locking in a sliding-frequency fiber laser.
abstract: We demonstrate a sliding-frequency mode-locked (SFM) erbium fiber laser generating 20 ps pulses with center wavelengths rapidly sweeping across a spectral range of 50 nm. Excess optical nonlinearity in the laser cavity leads to multipulsing, with a tendency to tight pulse bunching (<3 ns) at the fundamental cavity frequency of 25 MHz. The addition of a parallel optical delay line, with a path difference equal to a rational fraction of the cavity length, distributes the pulses uniformly across the entire cavity and achieves a harmonic SFM up to 1 GHz. The result establishes cavity nonlinearity as a critical design parameter for picosecond wavelength-swept lasers.
authors.affiliation: Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, BAR8, Boston, Massachusetts 02114, USA.
authors.forename: Carlo Amadeo
authors.initials: CA
authors.lastname: Alonzo
authors.forename: Seok H
authors.initials: SH
authors.lastname: Yun
mesh_terms: D053844:Lasers, Solid-State; D055620:Optical Phenomena