Unidirectional transmission in one dimensional photonic crystal composed of PT symmetric and magneto-optical materials

Abstract In this paper, we show nonreciprocal and extraordinary transmission in a well designed composite MPCs composed of two ternary PT-symmetric periodic system. Firstly, a pair of nonreciprocal defect resonant modes appears in the band gap due to the broken time-reversal symmetry of MO materials under a magnetic field when a defect layer is introduced into the multilayered structure. Next, when the gain/loss factors are introduced into the multilayered structure, the PT-symmetry breaking occurs naturally in the composite structure defect layer filled with the MO material, and the unique asymmetric nonreciprocal transmission can be realized. At the same time, by the different choices of incident angles, the magnetic fields on the MO materials and the gain/loss factors, the nonreciprocal transmission can be flexibly controlled and tuned. Moreover, the multilayered structure also presents broadband coherent perfect absorption ability when the gain/loss factors are further increased. Such distinguishing properties may provide these structures with attractive applications such as compact optical isolators, diodes, and wave absorbers.