Vortex fiber laser based on dual-band metasurface

The invention provides a vortex fiber laser based on a dual-band metasurface, which comprises a pump light source, a fiber reflector, a wavelength division multiplexer, a gain fiber, a collimator, a polarization beam splitter and the dual-band metasurface, and is characterized in that the dual-band metasurface comprises a plurality of metasurface units; each metasurface unit comprises a first metal layer, an insulating layer and a second metal layer which are arranged from top to bottom, the first metal layer comprises an inner circular ring with an opening and an outer circular ring with an opening at the overlook angle of the dual-band metasurface, and the inner circular ring and the outer circular ring have the same circle center; according to the scheme, on the basis of the metasurface with the inner circular ring and the outer circular ring, orthogonal linear polarization conversion is achieved through the openings of the two circular rings, then the metasurface can generate orbital angular momentum ligh