MINIATURE ERBIUM-YTTERBIUM FIBER FABRY-PEROT MULTIWAVELENGTH LASERS

We demonstrate stable simultaneous lasing of up to 29 wavelengths in m iniature 1- and 2-mm-long B3+:Yb3+ fiber Fabry-Perat lasers, The wavel engths are separated by 0.8 (100 GHz) and 0.4 nm (50 GHz), respectivel y, corresponding to the free spectral range of the laser cavity. The n umber of lasing wavelengths and the power stability of the individual modes are greatly enhanced by cooling the laser in liquid nitrogen (77 K): The polarization modes and linewidth of each wavelength are measu red with high resolution by heterodyning with a local oscillator, The homogeneous linewidth of tile Er3+:Yb3+ fiber at 77 K is determined to be similar to 0.5 nm, from spectral-hole-burning measurements, which accounts for the generation of a stable multiwavelength lasing comb wi th wavelength separations of 0.4 nm.