The tapered asymmetric directional coupler has the potential to realize high fabrication tolerance and high transmission efficiency on-chip mode multiplexer. However, the geometry parameter selection of tapered structure remains empirical. In this paper, we propose a design method for the tapered structure based on genetic algorithm. Combined with the adjusted coupling equations and interpolation method, lowtime- cost optimization can be realized. Three mode multiplexers (TE0&TE1, TE0&TE2 and TE0&TE5) are designed by our method. According to simulation results, the insertion loss of the designed devices is lower than 1.8 dB and the crosstalk is lower than −15 dB when the fabrication error is within required range (±10 nm for TE₀&TE₂ and TE₀&TE₅, and ±20 nm for TE₀&TE₁) in the bandwidth of 1.5–1.6 μm. In addition, the entire optimization process takes only 2 h for each device, which is around the time cost of a single 3D simulation.

锥形不对称定向耦合器具有实现高制造公差和高传输效率的片上模式多路复用器的潜力。但是，锥形结构的几何参数选择仍然是经验性的。本文提出了一种基于遗传算法的锥形结构设计方法。结合调整后的耦合方程和插值方法，可以实现低成本的优化。通过我们的方法设计了三种模式多路复用器（TE0＆TE1，TE0＆TE2和TE0＆TE5）。根据仿真结果，当制造误差在要求范围内时（TE ₀＆TE ₂和TE ₀＆TE的±10 nm），设计器件的插入损耗低于1.8 dB，串扰低于-15 dB 。对于TE ₀＆TE ₁）为±20 nm，带宽为1.5-1.6μm。此外，每个设备的整个优化过程仅花费2小时，这大约是单个3D仿真的时间成本。