Wide-spectrally-tunable CW and femtosecond linear fiber lasers with ultrabroadband loop mirrors based on fiber circulators

It is demonstrated for the first time that the fiber circulator-based loop reflectors exhibit an extremely wide spectral range. Fiber reflectors based on a commercially available circulator for a wavelength of 1064 nm provide a reflectance of greater than 90% (50%) in a spectral band with a width of 75 (180) nm. The application of such a reflector in a linear CW Yb laser in combination with the second prism reflector allows the smooth tuning of the laser wavelength in the range with a width of greater than 90 nm. The application of two ultrabroadband circulator-based reflectors in the linear all-fiber all-positive-dispersion mode-locked Yb laser makes it possible to generate unique combined femtosecond-picosecond pulses whose shortest component has a duration of less than 190 fs. The spectrum of ultrashort pulses is smoothly tuned in the range 1065–1115 nm owing to the prism reflector.