Basic mode field converter and construction method thereof

The invention discloses a fundamental mode field converter and a construction method thereof, and the converter comprises a narrow waveguide interface, a wide waveguide interface, and a main body which is connected with the narrow waveguide interface and the wide waveguide interface. The profile curve of the main body on the cross section parallel to the connecting line of the narrow waveguide interface and the wide waveguide interface is composed of two four-order Bezier curves in mirror symmetry. Compared with a simple trapezoidal contour of a fundamental mode field size converter in a traditional scheme, the fundamental mode field size converter designed by the invention has lower fundamental mode loss and lower high-order mode excitation ratio, so that the size of the mode field size converter can be remarkably reduced under the condition of keeping the same performance; the miniaturization of the photon system is facilitated, and the integration level is improved. 本发明公开了一种基模模场转换器及其构建方法，包括：窄波导接口、宽波导接口以及连接