Iteration design method for TE01-TE11 mode converter

Two improvements in the iteration method for mode converter design are presented, i.e. a reasonable initial step value in every iteration is given and coupled lines of less contribution are ignored to improve bandwidth. A TE01-TE11 mode converter is designed with the improved iteration method, whose ratio of waveguide radius to free space wavelength is 2.765 5. Simulation results show that its relative bandwidth reaches 6%, total length is 600 mm, and conversion efficiency is 99.14% at the central frequency. The total calculation time is 40 s. The CST simulation result agrees well with the coupled mode simulation one.