Broadband polarization-insensitive metamaterial perfect absorbers using topology optimization

Sze Ming Fu, Yan Kai Zhong, Nyan Ping Ju, Ming Hsiang Tu, Bo Ruei Chen, Shih-Chun Lin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

A novel scheme for a perfect hyperbolic metamaterial (HMM) absorber is proposed, and experimental verification is provided. It has been shown previously that tapered HMM stacks can provide adiabatic waveguiding over a wide spectral range and thus are an ideal opaque absorber. Here, nontapered shape-optimized HMM absorbers are proposed, which facilitates the fabrication and promotes the large-area applications such as thermophotovoltaics (TPV). In the synthesis of the optimal patterns, we use 5-harmonic rigorously coupled wave analysis (RCWA) and experimental trials to shorten the trial-and-error time. The best pattern provides an averaged broadband experimental absorption of 88.38% over λ = 1 μm to λ = 2 μm, which is comparable to the state-of-the-art experimental effort using tapered HMM. The nontapered nature can be easier to fabricate from the semiconductor processing viewpoint. The physics behind the pattern-optimized HMM cavity is the broadband light coupling by the air-cavity and the unbounded photonic density of the states (PDOS) associated with the HMM. The topology optimized air cavity effectively couples the incident photons into the metal-dielectric stacking, eliminating the need of sidewall tapers. We believe the proposed topology-optimization methodology benefits the future design of compact metamaterial perfect absorbers (MPA), sensors, antenna, and thermophotovoltaic emitters, and absorbers.

Original languageEnglish
Article number4600311
JournalIEEE Photonics Journal
Volume8
Issue number5
DOIs
StatePublished - 1 Oct 2016

Keywords

  • Diffractive optics
  • metamaterials
  • photovoltaic
  • plasmonics
  • silicon nanophotonics

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