Switchable Multi-Wavelength Erbium-Doped Fiber Pulsed Laser Based On Sagnac Ring Filter

As a branch of fiber laser research,switchable multi-wavelength pulsed fiber laser has the advantages of traditional fiber laser,but also has a flexible number of wavelength switchable,laser output with high peak power,narrow pulse width,which can be used in laser processing,laser distance measurement,lidar and laser medical applications.This paper focuses on the output performance of a switchable multiwavelength Erbium-Doped fiber pulsed laser based on Sagnac ring filter.Three different structures of switchable multi-wavelength fiber pulsed lasers are designed using pulse generation mechanism and multi-wavelength filter.Details of the work are as follows.First,we propose a multi-wavelength laser based on an electro optical modulator and a Sagnac ring filter,which adjusts the polarization controller to obtain a pulsed laser output with wavelength tuning and multiple wavelength intervals.The wavelength tuning range of single-wavelength laser output is 7 nm and that of dual-wavelength laser output is 5 nm,as well as three-wavelength pulsed laser output with three wavelength intervals and four-and five-wavelength pulsed laser output with four wavelength intervals,the proposed lasers have a wide range of applications due to their rich laser output states.Second,a multi-wavelength laser based on the Nonlinear Polarization Rotation(NPR)structure and Sagnac ring filter is proposed.When there is no NPR structure in the laser,the pulsed laser output is at most four wavelengths,while when the NPR structure is added to the laser,the pulsed laser output is at most nine wavelengths,proving that the NPR structure effectively suppresses the mode competition caused by the Erbium-Doped fiber and improves laser performance of the laser.Third,a multi-wavelength laser based on a Nonlinear Optical Loop Mirror(NOLM)and a Sagnac ring filter is proposed.In the experiment,the modified Sagnac ring filter functions as a wavelength selector for multi-wavelength laser output,and the NOLM is used as a pulse generator for multi-wavelength pulsed laser output with 40.45 kHz.