Fibre amplifying loop mirror with nonlinearity independent of the intensity of intra-cavity radiation

摘要

Among the demerits of standard nonlinear amplifying loop mirrors (NALM), one can single out the dependence of its reflectivity upon the intensity of the intra-cavity. This results in a relatively narrow range of radiation power, within which stable mode-locked operation of a fibre laser with NALM can be achieved. This work reports for the first time that in the process of generation, the NALM reflectivity may be controlled independently of the intra-cavity radiation power by using two different active media with independent pump sources. The newly proposed layout allows stable mode locking within a substantially broader radiation power range and enables achievement of record-high pulse parameters.