Gain-Assisted Plasmon Resonance Narrowing and Its Application in Sensing

Lijun Meng, Ding Zhao, Yuanqing Yang, F. Javier García de Abajo, Qiang Li, Zhichao Ruan, and Min Qiu

Phys. Rev. Applied 11, 044030 – Published 10 April 2019

Abstract

We demonstrate the viability of using high-order modes in localized optical resonances combined with gain media to dramatically reduce the linewidths of absorption spectra. Our theoretical study provides a rational design route for small-footprint absorption with a high quality factor, which is typically a trade-off for plasmonic light absorbers. Specifically, we design and numerically investigate a metal-insulator-metal absorber and a graphene Salisbury screen. Additionally, we study the potential application of these structures in sensing in order to achieve higher performance compared with conventional sensors based on the fundamental mode. Our approach, which can readily operate in a multiplexed fashion, has the potential for sensing minute amounts of analytes with a high figure of merit.

Received 31 July 2018
Revised 31 January 2019

DOI:https://doi.org/10.1103/PhysRevApplied.11.044030

Physics Subject Headings (PhySH)

Analytical chemistry Integrated optics Light propagation, transmission & absorption Metamaterials Nanoantennas Plasmonics

Solid-state detectors

Resonance techniques

Condensed Matter, Materials & Applied PhysicsAtomic, Molecular & Optical

Authors & Affiliations

Lijun Meng^1,2,3, Ding Zhao⁴, Yuanqing Yang⁵, F. Javier García de Abajo^2,6, Qiang Li³, Zhichao Ruan^1,3,*, and Min Qiu^3,7,8,†

¹Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics and State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, Zhejiang, China
²ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
³State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
⁴DTU Nanolab, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
⁵SDU Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark
⁶ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
⁷Institute of Advanced Technology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
⁸Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province, School of Engineering, Westlake University, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China

^*zhichao@zju.edu.cn
^†qiu_lab@westlake.edu.cn

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Issue

Vol. 11, Iss. 4 — April 2019

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Images

Figure 1
(a) Schematic view of the two silica/gold core-shell structures here considered. (b) Normalized absorption cross sections of core-shell cylinders supporting a dipolar mode without gain (blue curve), a quadrupolar mode without gain (red dashed curve), or a quadrupolar mode with gain (red solid curve) at 711 nm. (c) Normalized magnetic fields of a quadrupolar mode (peak A) and a dipolar mode (peak B), respectively, corresponding to the features labeled in the blue curve of (b). (d) Normalized magnetic fields of a quadrupolar mode (peak C) and a dipolar mode (peak D), respectively, associated with the red dashed curve in (b). (e) Radiative and resistive decay rates of a quadrupolar mode (related to peak E) at different gain levels. (f) Normalized magnetic field of the quadrupolar mode (peak E) of the red solid curve in (b) under the critical-coupling condition. Frames in (c),(d),(f) share the same color and line type as spectral curves in (b). Also, $| H_{0} |$ is the magnetic field amplitude of the incidence wave.
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Figure 2
Normalized absorption cross sections related to the peak E in Fig. 1 when the gain bandwidth of the gain medium takes different values.
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Figure 3
Absorption properties of infinite one-dimensional (1D) arrays illuminated by plane waves (a)–(c) and finite arrays illuminated by Gaussian beams (d). (a) Absorption spectra of the absorbers, respectively, supporting a fundamental mode without gain (blue curve), a higher-order mode without gain (red dashed curve), or a higher-order mode with gain (red solid curve) at 711 nm. The inset depicts the structure. (b) On-resonance normalized magnetic fields under the two different conditions considered in (a). The frames share the same color and line type as spectral curves in (a). (c) Absorption spectra at different incidence angles. (d) Absorption spectra for finite arrays of different size (i.e., number of unit cells). Both (c) and (d) correspond to the higher-order-mode structures.
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Figure 4
(a) A schematic view of a nanodevice for gas sensing. Grooves are filled with the targeted gas of index $n$ . (b) Absorption spectra when the gas takes different indices. The solid (dashed) curves correspond to the structure utilizing a higher-order (fundamental) mode.
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Figure 5
Absorption properties of infinite 1D arrays illuminated by plane waves (a)–(c) and finite arrays illuminated by Gaussian beams (d). (a) Absorption spectra of absorbers supporting a fundamental mode without gain (blue curve), a higher-order mode without gain (red dashed curve), or a higher-order mode with gain (red solid curve) at 2800 nm. The inset depicts the structure under consideration. (b) On-resonance normalized magnetic fields under the two different conditions examined in (a). The frames share the same color and line type as spectral curves in (a). (c) Absorbance as a function of incidence angle and wavelength. (d) Absorption spectra for finite arrays of different size (i.e., number of unit cells). Both (c) and (d) correspond to the higher-order-mode structures.
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Figure 6
(a) Schematic view of a nanodevice for thin molecular layer sensing. The molecular layer with a thickness of 10 nm is characterized by a refractive index $n$ . (b) Absorption spectra for different molecular layer indices. The solid (dashed) curves correspond to the structure utilizing the higher-order (fundamental) resonance.
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