Nonreciprocal self-collimation in two-dimensional gyromagnetic photonic crystals and its applications in signal separation

We investigate self-collimated electromagnetic waves in two-dimensional gyromagnetic photonic crystals (GPCs) fabricated by semi-cylinder rods. The nonreciprocal self-collimation transmission is found by means of band structure and equi-frequency contour (EFC) calculations. Progressively tilting flat EFC by optimizing the structure of GPC, we show that nonreciprocal spatial wavelength division can be achieved without any corrugations inside the structure. Further, the frequency range for the nonreciprocal spatial wavelength division can be flexibly manipulated by the external static magnetic field.