针对现有模式复用器的不足，根据有效折射率匹配效应，设计一种非对称平面光波导型模式复用/解复用器。波导结构由1个波导主臂和2个波导分支臂组成。研究了波导各项参数的确定准则，仿真分析了不同的波导底面宽度比对模式复用/解复用性能的影响，确定了最佳的波导底面宽度比，分析了基模和一阶模在波导中的传输过程和光场能量流动情况。结果表明：非对称平面光波导型模式复用/解复用器具有良好的模式复用和解复用性能，并且可以高效率地实现模式之间的转换，具有结构简单、模式转换效率较高、易于集成等优点。

Aiming at the shortcomings of the existing multiplexers, a pattern of the asymmetric planar waveguide type mode division multiplexer/demultiplexer is designed, based on the effective refractive index matching effect. Waveguide structure consists of a main boom and two waveguide branches. The parametric principle to design the asymmetric planar waveguide type mode division multiplexer/demultiplexer is discussed. The performance of mode multiplexing/de-multiplexing is simulated under different waveguide width ratios, and the best waveguide width ratio is determined. The transmission process and the light field energy flow processes of fundamental mode and first-order mode are analyzed. The simulation results show that the asymmetric planar waveguide type mode division multiplexer/demultiplexer has a good performance of mode division multiplexing/demultiplexing, and the mode conversion can be realized efficiently. The properties, such as simple structure, high mode conversion efficiency, easy integration, make it more suitable for mode division multiplexing communication.