Through in-depth research, Zhao Wei, Zhang Wei, Wang Yishan and other researchers of XIOPM invented an σ cavity ultrashort pulse fiber laser with variable output rate and won the national invention patent.

The fiber laser composes of reflecting SESAM, NOLM, the first polarization controller, WDM and the second polarization controller. The incident end of WDM couples a pumping source, and the wave combining end of WDM successively couples with the second polarization controller and transmission SESAM through doped optical fibers. NOLM composes of nonlinear optical loop which consists of single mode fiber and central coupler. A group optical fiber of central coupler connects with the WDM and the other group is used as the emitting end of the entire laser. NOLM also has the variable optical attenuator which is at the unsymmetrical place with the nonlinear optical loop that consists of single mode fiber. The optical laser has the adjustable transmittance and can still output laser when the central coupling ration is 0.5. It solves the technical problems of the traditional σ cavity ultrashort pulse fiber laser and has wide application prospects.