Miniature erbium:ytterbium fiber Fabry-Perot multiwavelength lasers

We demonstrate stable simultaneous lasing of up to 29 wavelengths in miniature 1mm and 2mm long Er3+:Yb3+ fiber Fabry-Perot lasers. The wavelengths are separated by 0.8nm (100GHz) and 0.4nm (50GHz) respectively, corresponding to the free spectral range of the laser cavity. The number of king wavelengths and the power stability of the individual modes are greatly enhanced by cooling the laser in liquid nitrogen (77K). The polarization modes and linewidth of each wavelength are measured with high resolution by heterodyning with a local oscillator. The homogeneous linewidth of the Er3+:Yb3+ fiber at 77K is determined to be ~0.5nm, from spectral hole-burning measurements, which accounts for the generation of a stable multiwavelength lasing comb with wavelength separations of 0.4nm