Demonstration of a large-scale optical exceptional point structure

Liang Feng,Xiang Zhang,Hanyu Zhu,Peng Zhang,Xiaobo Yin,Xuefeng Zhu,Sui Yang,Yuan Wang

doi:10.1364/oe.22.001760

Abstract

We report a large-size (4-inch) optical exceptional point structure at visible frequencies by designing a multilayer structure of absorbing and non-absorbing dielectrics. The optical exceptional point was implemented as indicated by the realized unidirectional reflectionless light transport at a wafer scale. The associated abrupt phase transition is theoretically and experimentally confirmed when crossing over the exceptional point in wavelengths. The large scale demonstration of phase transition around exceptional points will open new possibilities in important applications in free space optical devices.

Highlights

Optical losses are responsible for power attenuation, and typically degrade the performance of optical devices
The unidirectional reflectionless light transport was clearly demonstrated around the wavelength of 520 nm in measurements, where reflection in the forward direction was diminished owing to the implemented exceptional point
The demonstrated exceptional point and the phase transition around it originate from the singularity in the complex eigen spectrum

Summary

Introduction

Optical losses are responsible for power attenuation, and typically degrade the performance of optical devices. Designed photonic synthetic matters, which take advantage of optical losses by engineering the entire complex dielectric permittivity plane, may be investigated to mimic the complex non-Hermitian Hamiltonians in quantum mechanics [2] and realize unique directional light transport and novel devices [3,4,5,6,7,8,9] at the parity-time phase transition point, a type of exceptional points. Instead of minimizing optical losses, we intentionally utilized the losses together with the modulated index of refraction By engineering their interplay, we developed a 4-inch sized multilayer exceptional structure and demonstrated its associated accidental degeneracy at the exceptional point. Because of the intrinsic planar configuration, our exceptional point structure is highly scalable in fabrication and can be implemented in both micro- and macro-scale applications

Exceptional point and phase transition

Conclusion