Multiwavelength oscillations of Ytterbium-doped fiber laser

Multiwavelength oscillation characteristics of ytterbium-doped fiber ring laser with a Sagnac comb filter at both room and liquid Nitrogen (77 K) temperatures are investigated. The experimental results show that, at both room temperature and 77 K, the ytterbium-doped fiber (YDF) exhibits obviously inhomogeneous gain broadening, which results that the lasing lines of the laser increases with the increase of the pump power. However, due to the homogeneous gain broadening of the YDF, the gain inhomogeneity of the YDF at room temperature may not be strong enough to compensate the intrinsic unevenness of the YDF gain spectrum, leading to a phenomenon of potential lasing wavelengths missing. Moreover, when the wavelength spacing decreases to 0.8nm, the wavelength competition caused by the homogeneous gain broadening of the YDF results in the decrease of the stability of multiwavelength oscillations. At 77 K, however, the inhomogeneous gain broadening of the YDF becomes stronger. For a spacing of 0.8nm, 32 stable lasing lines without any potential lasing wavelengths missing between neighboring lasing wavelengths have been obtained.