Double exceptional points in grating coupled metal-insulator-metal heterostructure

Mai，Jianming1; Chen，Yu2; Li，Guixin2; Cheah，Kok Wai1

2022-10-24

10.1364/OE.472961

Optics Express   Impact Factor & Quartile

1094-4087

In this work we theoretically study the exceptional points and reflection spectra characteristics of a grating coupled metal-insulator-metal heterostructure, which is a non-Hermitian system. Our results show that by selecting suitable geometrical parameters with grating periodicity @150 nm, that satisfy zero reflection condition, double exceptional points appear in a mode bifurcation regime. Furthermore, the thickness of partition metal layer between two cavities plays an important role in controlling the reflection properties of the heterostructure. There is a clear mode splitting when the partition layer allows strong coupling between the two cavity modes. Conversely, in weak coupling regime the mode splitting becomes too close to be distinguished. Moreover, the vanishing of reflection leads to unidirectional reflectionless propagation, which is also known as unidirectional invisibility. With grating periodicity ≥400nm, the transmissions for forward and backward incident directions are no longer the same due to the generation of diffraction. High contrast ratio (≈1) between the two incident directions leads to asymmetric transmission. This work lays the basis for designing double exceptional points and asymmetric transmission in coupled non-Hermitian photonics system. The proposed heterostructure can be a good candidate for new generation optical communications, optical sensing, photo-detection, and nano-photonic devices.

English

Others

Hong Kong Arts Development Council[12303019];Hong Kong Arts Development Council[AoE/P-02/12];

2-s2.0-85140251768

Scopus

1.Department of Physics,Institute of Advanced Materials,Hong Kong Baptist University,Kowloon Tong,Hong Kong
2.Department of Materials Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China

Mai，Jianming,Chen，Yu,Li，Guixin,et al. Double exceptional points in grating coupled metal-insulator-metal heterostructure[J]. Optics Express,2022,30(22):40053-40062.

Mai，Jianming,Chen，Yu,Li，Guixin,&Cheah，Kok Wai.(2022).Double exceptional points in grating coupled metal-insulator-metal heterostructure.Optics Express,30(22),40053-40062.

Mai，Jianming,et al."Double exceptional points in grating coupled metal-insulator-metal heterostructure".Optics Express 30.22(2022):40053-40062.