Traditional FBT couplers are widely used in the field of optical communication and optical sensing, but usually the FBT coupler has a package size of 3.0×25mm or more, and the spectral width and polarization-preserving extinction ratio are limited, so that the FBT coupler is in some The application of a particular scenario is limited. Compared to the FBT coupler, the micro-optical coupler has a smaller size, a higher spectral width, and an excellent extinction ratio retention performance.
