Multiple Metamaterial Pattern Integration for Polarization Selective Photodetector Applications
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Multiple Metamaterial Pattern Integration for Polarization Selective Photodetector Applications Corey Shemelya1,2, Nicole A. Pfiester1, Dante DeMeo1, Thomas Rotter3, Ganesh Balakrishnan3, and Thomas E. Vandervelde1* 1
Electrical and Computer Engineering Department, Tufts University, 161 College Ave. Medford MA, 02155, U.S.A.
2 Electrical and Computer Engineering Department, The Technical University of Kaiserslautern, ErwinSchrödinger-Straße 1, 67663 Kaiserslautern, Germany
3 Electrical and Computer Engineering Department, The University of New Mexico, 1313 Goddard SE, Albuquerque, NM 87106, U.S.A.
*[email protected]
ABSTRACT
Interest in active metamaterial (MM) devices has recently increased due to their potential for tunable, switchable, and scalable optical responses. More specifically, a dynamic, on-chip MM polarizer has applications ranging from material characterization to sensing without the need for cumbersome external filters. This work demonstrates efforts to optimize MM devices for dynamic polarization filtering by combining elements from split-ring resonators, wirepairs, and fishnet patterns. The polarization grid has been designed to operate under an applied voltage with simulated on/off ratios of 75% and dynamic polarization selectivity of 70%. Samples have been fabricated using epitaxial GaAs on sapphire with various n-type doping concentrations to approximate electrical tuning.
INTRODUCTION The first metamaterials, the split ring resonator (SRR), operated exclusively at GHz frequencies; however, recent research utilizing various micro/nano-fabrication methods have resulted in metamaterials (MMs) designed to operate at visible and infrared (IR) frequencies [1-3]. Although there are many MM designs, of particular interest to this work are the SRR, optical fishnet, and wire-pair metamaterial designs [1,2,4]. These structures maintain many similarities and difference. For example, incremental modification of the SRR led to comparison with repeating patterns of nano-bars [4,5]. Nano-bars have since become known as split-wire pairs (SWPs). Like SRRs, SWPs operate notch filters with a Cornell high University transmission largesubject absorption at Core Downloaded from as https://www.cambridge.org/core. Library, onwindow 19 Jan 2018and at 04:58:10, to the Cambridge terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/adv.2018.43
resonance [5]. Therefore, the SWPs generally provide polarization sensitivity similar to metallic gratings typically used in polarization grids [6,7]. Optical fishnets, by comparison, generate a bandpass resonant response, and utilize two metallic layers with a dielectric spacer. The thickness of these layers plays a large role in the final response, and as such require careful design. Repeating patterns of circular or square holes are then etched through the structure, creating an MM which excels at narrow band transmission [8,9]. This work aims to combine these three designs to produce a polarization-dependent MM response which can l
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