Saturable absorber for fiber laser mode-locking, fiber Bragg grating with a saturable absorption property and mode-locked fiber laser

摘要

A saturable absorber for fiber laser mode-locking comprises a single-mode optical fiber (1) having a fiber portion (2) which is tapered or in which at least one longitudinal groove or at least one transverse hole is formed. Said tapered fiber portion is coated with a composite bleachable material (3), or said grooves or holes are filled with said composite material. In order to broaden a range of applications of the saturable and to extend its service life, said composite bleachable material comprises an inorganic matrix with an index of refraction similar to an index of refraction of the optical fiber and a nonlinear material embedded into said inorganic matrix, wherein said nonlinear material possesses a nonlinear absorption property and bleaches when exposed to laser radiation of intensity from 5MW/cm 2 to 500MW/cm 2 , while a waist diameter and of said tapered fiber portion or a number of grooves or holes and their configuration are chosen to satisfy a condition that laser light while propagating in the saturable absorber experiences losses between 1% and 50%. The proposed saturable absorber can be used in a resonator of a mode-locked fiber laser or incorporated into a construction of a fiber Bragg grating.