Research Progress of Single-Frequency Fiber Lasers

Single-frequency lasers(SFL) have been successfully used in temperature sensing,ranging,and coherent communications.Many techniques,such as fiber Bragg grating based mode-discriminator,ultrashort fiber cavity with distributed feedback mechanism,and saturable absorber based mode filters,etc.,have been developed for the purpose of generating a single-frequency laser in a relatively long fiber cavity.Some common methods and the breakthrough of realizing single-frequency fiber lasers in recent years from the angle of the resonant cavity structure are summarized,and the comparative analysis and corresponding improvement are made.