Tunable and interval-adjustable multi-wavelength erbium-doped fiber laser based on cascaded filters with the assistance of NPR

Abstract

A novel widely tunable and interval-adjustable multi-wavelength erbium-doped fiber laser (EDFL) is experimentally demonstrated in this paper. It is based on the cascaded structure of two-segment Sagnac filter and Lyot filter with the assistance of nonlinear polarization rotation (NPR). By properly adjusting the polarization controllers (PCs) in the laser cavity, the output wavelengths with different flexible lasing states can be obtained, such as tunable single-, dual-, triple-wavelength outputs with a tuning range more than 18 nm. The outputs of quad-, quintuple-, sextuple- and septuple-wavelength can also be tuned, but the step size of the tuning is not fixed due to the intense wavelength competition. In addition, the outputs can achieve changes in wavelength interval. The switchability and tuning range of the laser have been greatly improved, and the wavelength interval adjustment is more flexible. The maximum SMSR of the output laser can up to 47 dB. This EDFL can be used in optical fiber sensing, WDM network and other fields desiring very flexible optical source.