Original waveguide shapes have been calculated by using numerical optimisation techniques which enable efficient, short tapers and mode converters to be fulfilled. Theorical results obtained for TE0m modes are discussed. An experimental study on a TE02-TE01 "taper-converter" is presented: its measured efficiency is 99.7%.
"Ultra compact taper mode converter design", Proc. SPIE 1514, 15th International Conference on Infrared and Millimeter Waves, 151476 (12 December 2017); doi: 10.1117/12.2301668; https://doi.org/10.1117/12.2301668