Abstract

Weak irregular nonlinear interactions of a large number of cavity modes are responsible for practically important characteristics of fibre lasers, such as spectra of generated radiation. The total generated fibre laser power is distributed between millions of resonator modes, each with very small amplitude. However, the overall effect of the interactions between such small amplitude modes is easily observable. The nonlinear Kerr effect in fibre affects the propagation of light in the cavity and leads to a nonlinear mixing of longitudinal modes. As a result, the resonator is not linear and the operation and performance of such lasers is changed with changing power. For instance, the spectra of generated radiation experience spectral broadening as the laser power increases. Despite fast progress in fibre lasers and their growing applications, there remains a surprising lack of a comprehensive understanding of the underlaying physics behind their operation, as well as such practical features as fibre laser spectral characteristics. This is because fibre laser is not only a remarkable engineering device, but also a complex nonlinear physical system with a rich repertoire of dynamic behaviour and phenomena.

© 2015 IEEE