Temperature dependence of the radiation wavelength of a fibre laser

A model of a fibre laser is proposed which gives an analytic expression relating the laser wavelength to the main parameters of the laser. It is shown that there exists a region of the ambiguous dependence of the laser wavelength on the temperature and length of the active medium. Experimental results agree quantitatively with the theoretical model in a broad spectral range of laser radiation. Two-wave lasing without an intracavity selecting element is predicted and observed for the first time.