17 fs environmentally stable erbium-doped all-fiber 23.76 MHz oscillator with extra-cavity nonlinearity and dispersion management

We demonstrate generation of both 17 fs ultrashort pulses and 862 nm spanning supercontinuum (SC) directly from an erbium-doped fiber (EDF) oscillator, utilizing extra-cavity management of nonlinearity and second-order dispersion using a combination of commercially available SMF-28 and specially developed homemade fiber with anomalous dispersion and enhanced nonlinearity. The simple but accurately designed fiber ring laser, passively mode-locked by nonlinear polarization evolution, offers a self-starting pulse generation with a dechirped duration of 51.8 fs as well as a 19.4 mW average power, 0.81 nJ pulse energy, and 13.9 kW peak power at a 23.76 MHz repetition rate and 1560 nm central wavelength. The increased extra-cavity nonlinearity enabled supercontinuum generation with visible light components corresponding to the second-harmonic generation (SHG). Implementation of a thermally stabilized case and environmental isolation resulted in highly stable self-started mode-locking operation, with a relative intensity noise of -140 dBc/Hz (at 1 MHz) and only 0.2% instability of average power during a 6 h free-running measurement.