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S-parameters, non-Hermitian ports and the finite-element implementation in photonic devices with -symmetry
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论文类型：期刊论文
发表刊物：Opt. Express
所属单位：光电学院，国家光电研究中心
刊物所在地：美国
学科门类：工学
项目来源：自然科学基金
文献类型：J
卷号：27
期号：13
页面范围：17648-17657
关键字：无
DOI码：10.1364/OE.27.017648
发表时间：2019-02-13
教研室：c716
摘要：In Hermitian photonic devices, S-parameters, i.e., the elements of a scattering matrix based on integrated power flux and Hermitian modal orthogonality, are used to account for the transmission or reflection of light from one port to another. The definition of S-parameters in Hermitian settings becomes inappropriate in the non-Hermitian optical environment. Here we revisit the fundamental problems associated with extracting the S-parameters of light in photonic 𝒫𝒯-symmetric devices, i.e., waveguides or coupled waveguide-cavity systems, wherein the waveguide ports themselves may also be non-Hermitian. We first use the bi-orthogonal inner product that restores the modal orthogonality on the waveguide ports containing balanced gain and losses to quantify the modal overlapping instead of Hermitian inner product. Secondly, a finite element implementation is proposed and realized to extract the S-parameters on non-Hermitian ports. Lastly, we illustrate our approach of calculating the S-parameters on non-Hermitian ports via two waveguide-lattice structures. The numerical results of S-parameters are validated against the constraints imposed by reciprocity and 𝒫𝒯-symmetry.
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