Tunable and switchable erbium-doped fiber laser based on the parallel filter of the FBGs embedded in Sagnac ring and the in-line MZI

Tuning of laser frequency spacing output by lasers via fiber ring filter banks

“…The longer cavity length of the ring cavity allows for the flexible insertion of tuning and filtering components, which expands the tuning range and results in a narrower laser linewidth. Currently, prominent wavelength-selective devices include Fabry-Perot filters [7] , fiber Sagnac ring filters [8] , fiber Lyot filters [9] , Mach-Zehnder interferometer filters [10][11] , and multi-fiber ring-structure filters [12][13] , among others. This paper investigates the filtering characteristics of fiber ring filters.…”