Abstract
The authors demonstrate a feasible design of a one-dimensional non-Hermitian Su-Schrieffer-Heeger model based on photonic coupled resonant optical waveguides. The phase transition points are different from those of the periodic boundary, thus revealing a non-Bloch bulk-boundary correspondence. Moreover, the field distribution is found to be exponentially localized at the ends of an open-boundary chain, which demonstrates a non-Hermitian skin effect.
Highlights
The non-Hermitian Hamiltonian associated with open systems [1,2,3,4] and gain/loss media [5,6,7] has inspired significant research activities in many areas of physics and engineering [8,9,10,11,12,13]
We report a feasible design of a onedimensional (1D) non-Hermitian Su-Schrieffer-Heeger (SSH) model [57,58,59,60], which is a one-dimensional tight-binding model whose topological features arise from alternating offdiagonal tunneling strengths, based on the photonic coupled resonant optical waveguides (CROWs)
The Q factor of the resonant ring is so high that energy cannot be completely coupled out effectively; only a small part will be localized in the ring, which means that the field is still distinctly distributed in the upper semicircle of the link ring
Summary
The non-Hermitian Hamiltonian associated with open systems [1,2,3,4] and gain/loss media [5,6,7] has inspired significant research activities in many areas of physics and engineering [8,9,10,11,12,13]. There has been growing interest in the topological properties of non-Hermitian EPs, such as Weyl exceptional rings [20,21,22], bulk Fermi arcs [23], and half-integer topological charges [23]. Another remarkable phenomenon of non-Hermitian systems is the non-Hermitian skin effect, meaning that all eigenstates are localized at the boundary. The photonic non-Hermitian skin effect may provide a mechanism to strongly localize the light at the boundary and pave the way for achieving broadband lower-dimensional light trapping. Our design and results are more applicable and have the potential to be used in combination with silicon-based photonics, which may provide a feasible way for light manipulation and the design of optical devices such as optical couplers, beam splitters, lasers, and so on
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