Active mode-locked bismuth-based short-cavity fiber ring laser

We propose and experimentally demonstrate a wavelength-tunable actively mode-locked short-cavity fiber ring laser employing a 151-cm-long bismuth-oxide-based highly nonlinear erbium-doped fiber (Bi-HNL-EDF). A continuous wavelength tuning covering both the C-band and the L-band can be achieved by utilizing the wide gain bandwidth of the Bi-HNL-EDF. High nonlinearity of the Bi-HNL-EDF also collaborates with spectral filtering by an optical bandpass filter to suppress the supermode noise quite effectively. Total length of the ring cavity including all optical components is as short as 8 m. Back-to-back bit-error-rate measurements also confirm bit-error-free mode-locking operation throughout the entire wavelength tuning range.