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 circulatorbased 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 appli� cation of two ultrabroadband circulatorbased reflectors in the linear allfiber allpositivedispersion mode� locked Yb laser makes it possible to generate unique combined femtosecond-picosecond pulses whose short� est 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.