Continual mode transformation in a unidirectional compound waveguide

We propose a new mechanism to achieve mode transformation. In a unidirectional air waveguide we place some metal slabs to form the unidirectional edge loop. Based on the effect of mode interference, the even mode or the odd mode can be completely canceled from their degenerated state through a precise adjustment of slab position, which leads to another mode to be released. By this mechanism, we have achieved continual transformations between even mode and odd mode.