2020年论文发表
发布时间：2020-12-14
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Our paper "Switching between singular points in non-PT-symmetric multilayer structures using phase-change materials" by Yin Huang*, Lanyan Wang, Yuecheng Shen*, and Georgios Veronis is accepted in Optics express.
Abstract: We investigate the switching between singular points in non- parity-time-symmetric multilayer structures using phase-change materials at the optical communication wavelength. We first show that absorbing singularities can be switched to exceptional points (EPs) in a two-layer structure consisting of a phase-change material layer and a lossy layer by switching the phase-change material Ge2Sb2Te5(GST) from its crystalline to its amorphous phase. We also show that spectral singularities (SSs) can be switched to EPs in a three-layer structure consisting of a lossless dielectric layer sandwiched between a GST layer and a gain layer by switching the GST from its crystalline to its amorphous phase. We then show that self-dual SSs can be switched to unidirectional spectral singularities in a three-layer structure consisting of a lossy layer sandwiched between a GST layer and a gain layer by switching the GST from its amorphous to its crystalline phase. In addition, at the unidirectional spectral singularity, zero reflection from one side and infinite reflection from the opposite side are simultaneously realized. We finally show that we can design an active device with large modulation depth achieved by a very small variation of the imaginary part of the refractive index of the active absorbing material in the lossy layer. Our results could potentially contribute to the development of a new generation of singularity-enhanced switchable optical devices.
