Optical fiber mode selection coupler based on symmetrical double-core few-mode optical fiber

The invention provides an optical fiber mode selection coupler based on a symmetrical double-core few-mode optical fiber. The coupler structurally comprises a section of double-core optical fiber, andis characterized in that a first fiber core 2 and a second fiber core 3 are arranged in an optical fiber cladding 1 along the extending direction of the optical fiber cladding; the parameters of thetwo fiber cores are the same, and the normalization frequency V of each fiber core meets the condition that V is larger than 2.405, that is, the number of supported modes is larger than or equal to 2when each fiber core exists independently. The optical fiber mode selection coupler has the advantages that compared with a fused biconical taper type optical fiber mode selection coupler, the opticalfiber mode selection coupler based on the double-core optical fiber has the advantages of being stable in structure, controllable in parameter and the like, a longer coupling area can be achieved, and multi-wavelength stable wo