Transformation of unidirectional modes and split of channel through a cross waveguide

•The unidirectional waveguide modes have been achieved.•The mode transformation occurs in a cross waveguide.•A waveguide splitter and a zero-index waveguide are achieved.

The unidirectional waveguide plays a key role in optical communication system. The unidirectional waveguide modes have two forms, short wave and long wave. In order to simultaneously achieve the two kinds of unidirectional waveguide modes, we design a cross waveguide basing on the two-dimensional magneto-optical photonic crystals (2D MO PCs) and make a numerical study through the band calculations and finite element method. The horizontal unidirectional waveguide with a short wavelength is split into two vertical unidirectional waveguides with infinite wavelength. Transformation of unidirectional modes, a waveguide splitter and a zero-index waveguide are simultaneously achieved.