摘要
Exceptional points(EPs),at which two or more eigenvalues and eigenstates of a resonant system coalesce,are associated with non-Hermitian Hamiltonians with gain and/or loss elements.Dynamic encircling of EPs has received significant interest in recent years,as it has been shown to lead to highly nontrivial phenomena,such as chiral transmission in which the final state of the system depends on the encircling handedness.Previously,chiral transmission for a pair of eigenmodes has been realized by establishing a closed dynamical trajectory in parity-time-(PT-)or anti-PT-symmetric systems.Although chiral transmission of symmetry-broken modes,more accessible in practical photonic integrated circuits,has been realized by establishing a closed trajectory encircling EPs in anti-PTsymmetric systems,the demonstrated transmission efficiency is very low due to path-dependent losses.Here,we demonstrate chiral dynamics in a coupled waveguide system that does not require a closed trajectory.Specifically,we explore an open trajectory linking two infinite points having the same asymptotic eigenmodes(not modes in PT-and anti-PT-symmetric systems),demonstrating that this platform enables high-efficiency chiral transmission,with each eigenmode localized in a single waveguide.This concept is experimentally implemented in a coupled silicon waveguide system at telecommunication wavelengths.Our work provides a new evolution strategy for chiral dynamics with superior performance,laying the foundation for the development of practical chiral-transmission devices.
基金
National Natural Science Foundation of China(Grant No.12074137)
National Key Research and Development Project of China(Grant No.2021YFB2801903)
Science,Technology and Innovation Commission of Shenzhen Municipality(Grant No.JCYJ20220530161010023)
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology)
D.N.C.was partially supported by AFOSR MURI(FA9550-18-1-0235).
作者简介
Correspondence:Lin Chen(chen.lin@mail.hust.edu.cn)。
