Title: Broadband Polarization-Insensitive Metamaterial Perfect Absorbers Using Topology Optimization
Authors: Fu, Sze Ming
Zhong, Yan Kai
Ju, Nyan Ping
Tu, Ming-Hsiang
Chen, Bo-Ruei
Lin, Albert
Department of Electronics Engineering and Institute of Electronics
Keywords: Diffractive optics;metamaterials;photovoltaic;plasmonics;silicon nanophotonics
Issue Date: Oct-2016
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 lambda = 1 mu m to lambda = 2 mu m, 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.
URI: http://dx.doi.org/10.1109/JPHOT.2016.2602335
ISSN: 1943-0655
DOI: 10.1109/JPHOT.2016.2602335
Volume: 8
Issue: 5
Appears in Collections:Articles