Study of Fiber Bragg Grating Spectral Overlapping for Laser Structures

In this letter, different parameters of the spectral overlapping filtering technique have been analyzed for laser structures. Despite the promising preliminary experimental results obtained using this filtering technique, the optimization of the fiber Bragg grating (FBG) parameters to reduce the bandwidth of the achieved filter depending on the fiber laser requirements and configuration, should be performed. The simulated results have been confirmed during the experimental tests, where the same bandwidths and power evolutions have been measured using a ring laser configuration. This technique has been also tested for very narrow filtering purposes by achieving the single longitudinal mode operation with a ring cavity of L ≈ 8 m, using only two uniform FBGs.