Random Raman fiber laser based on a twin-core fiber with FBGs inscribed by femtosecond radiation.

Narrowband Raman lasing in a polarization-maintaining two-core fiber (TCF) is demonstrated. Femtosecond point-by-point inscription of fiber Bragg gratings (FBGs) in individual cores produces a half-open cavity with random distributed feedback. The laser linewidth in the cavity with a single FBG inscribed in one core of the TCF reduced by ∼2 times with respect to the cavity with a fiber loop mirror. It is shown that the inscription of two FBGs in different cores leads to the formation of a Michelson-type interferometer, leading to the modulation of generation spectra near threshold. This technique offers new possibilities for spectral filtering or multi-wavelength generation.

All-fiber holmium distributed feedback laser at 2.07 µm.

In this Letter, we present the results on fabrication and investigation of a holmium (Ho) distributed fiber laser based on a π-phase-shifted FBG inscribed in a heavily Ho-doped fiber by IR femtosecond laser pulses. Single-polarization and single-transverse mode operation regimes were observed with a linewidth of the order of 10 kHz and output power up to 53 mW at 2.07 µm. Lasing regimes are compared for room and cryogenic (77 K) temperatures of the laser cavity. To the best of our knowledge, this is the first realization of such type of fiber laser based on holmium active medium.