Colossal Terahertz Field Enhancement Using Split-Ring Resonators with a Sub-10 nm Gap

Kim, Nayeon; In, Sungjun; Lee, Dukhyung; Rhie, Jiyeah; Jeong, Jeeyoon; Kim, Dai‐Sik; Park, Namkyoo

doi:10.1021/acsphotonics.7b00627

Cited by 48 publications

(33 citation statements)

References 32 publications

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“…Recently, Kim et al [99] proposed the implementation of an SRR array with sub-10 nm gap with a lattice periodicity of 100 µm, a side length for each SRR of 80 µm, and nanogap widths of only 5 and 10 nm, as shown in Figure 7a, employing a more elaborated manufacturing technique, but sharing the main aspects of atomic layer lithography.…”

Section: New Manufacturing Techniques: Atomic Layer Lithographymentioning

confidence: 99%

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Terahertz Sensing Based on Metasurfaces

Beruete

Jáuregui-López

2019

Advanced Optical Materials

234

104

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The terahertz (THz) band has very attractive characteristics for sensing and biosensing applications, due to some interesting features such as being a non‐ionizing radiation, very sensitive to weak interactions, thus, complementing typical spectroscopy systems in the infrared. However, a fundamental drawback is its relatively long wavelength (10–1000 µm) which makes it blind to small features, hindering seriously both thin‐film and biological sensing. Recently, new ways to overcome this limitation have become possible thanks to the advent of metasurfaces. These artificial structures are planar screens usually made of periodic metallic resonators and whose electromagnetic response can be controlled at will by design. This design freedom allows metasurfaces to surpass the restrictions of classical THz spectroscopy, by creating fine details comparable to the size of the thin films or microorganisms under test. The strong field concentration near these small metasurface details at resonance makes them highly sensitive to tiny variations in the nearby environment, allowing for an enhanced detection more accurate than classical THz spectroscopy. The main advances in THz metasurface sensors from a historical as well as application‐oriented perspective are summarized. The focus is put mainly on thin‐film and biological sensors, with an aim to cover the most recent advances in the topic.

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Section: New Manufacturing Techniques: Atomic Layer Lithographymentioning

confidence: 99%

“…Two resonance dips were identified in the transmission spectra recorded from 0.1 to 1.6 THz, the first one appearing at 0.25 THz and the second Figure 7. [99] Copyright 2018, American Chemical Society. [99] along with a microscopic image of the fabricated structure (top).…”

Section: New Manufacturing Techniques: Atomic Layer Lithographymentioning

confidence: 99%

Terahertz Sensing Based on Metasurfaces

Beruete

Jáuregui-López

2019

Advanced Optical Materials

234

104

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“…Although these examples work well as sensing platforms, they usually suffer from a relatively poor performance achieving small sensitivity values (less than 80 in the best case). Recently, new fabrication techniques have pushed forward the field by allowing the creation of nanogap structures, able to achieve values of the sensitivity of the order of 4400, at the expense of requiring a relatively complex manufacturing procedure.…”

Section: Sensitivity and Fom For Each Analyte Thickness For The Samplmentioning

confidence: 99%

Labyrinth Metasurface Absorber for Ultra‐High‐Sensitivity Terahertz Thin Film Sensing

Jáuregui-López

Rodríguez-Ulibarri

Urrutia

et al. 2018

Physica Rapid Research Ltrs

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In this work, a labyrinth metasurface sensor operating at the low-frequency edge of the THz band is presented. Its intricate shape leads to a high electric field confinement on the surface of the structure, resulting in ultrasensitive performance, able to detect samples of the order of tens of nanometers at a wavelength of the order of millimeters (i.e., five orders of magnitude larger). The sensing capabilities of the labyrinth metasurface are evaluated numerically and experimentally by covering the metallic face with tin dioxide (SnO 2 ) thin films with thicknesses ranging from 24 to 345 nm. A redshift of the resonant frequency is observed as the analyte thickness increases, until reaching a thickness of 20 μm, where the response saturates. A maximum sensitivity of more than 800 and a figure of merit near 4500 nm À1 are achieved, allowing discriminating differences in the SnO 2 thickness of less than 25 nm, and improving previous works by a factor of 35. This result can open a new paradigm of ultrasensitive devices based on intricate metageometries overcoming the limitations of classical metasurface sensor designs based on periodic metaatoms.The THz band (ranging from 0.1 to 10 THz) has been historically known as the "THz gap" [1] due to the lack of efficient emitters and receivers operating in this regime at ambient temperature. However, a series of recent breakthroughs have helped to bridge this gap, to the point that nowadays it is a field of intense and multidisciplinary research with many applications coming into reality in numerous sectors, like medicine, security, communications, space, or sensing, among others. [2] Sensing at THz is of special relevance, because many substances exhibit molecular vibrations opening new routes for high performance detection platforms, allowing the identification of certain gases or solids that show absorption lines in this frequency range. Moreover, due to a larger wavelength and deeper penetration into many materials versus the visible or infrared ranges, THz waves are promising for examining optically opaque coatings. To date, several strategies have been followed to develop THz sensing devices such as plasmonic structures, [3] metamaterials, [4] and frequency selective surfaces, [5] among others.

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“…The operating principle lies in strong capacitive coupling between neighboring metallic resonators. [47][48][49][50] As shown in Figure 2b, a deep subwavelength-scale spacing between metallic resonators results in strong charge accumulation on the edge of I-shaped resonators and consequently induces a large electric dipole moment of the meta-atom. The retrieved complex refractive index is plotted in Figure 2c, where a very high refractive index in a broad spectral range can be clearly seen.…”

Section: High Refractive Indexmentioning

confidence: 99%

Metamaterials for Enhanced Optical Responses and their Application to Active Control of Terahertz Waves

et al. 2020

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Metamaterials, artificially constructed structures that mimic lattices in natural materials, have made numerous contributions to the development of unconventional optical devices. With an increasing demand for more diverse functionalities, terahertz (THz) metamaterials are also expanding their domain, from the realm of mere passive devices to the broader area where functionalized active THz devices are particularly required. A brief review on THz metamaterials is given with a focus on research conducted in the authors' group. The first part is centered on enhanced THz optical responses from tightly coupled meta‐atom structures, such as high refractive index, enhanced optical activity, anomalous wavelength scaling, large phase retardation, and nondispersive polarization rotation. Next, electrically gated graphene metamaterials are reviewed with an emphasis on the functionalization of enhanced THz optical responses. Finally, the linear frequency conversion of THz waves in a rapidly time‐variant THz metamaterial is briefly discussed in the more general context of spatiotemporal control of light.

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Colossal Terahertz Field Enhancement Using Split-Ring Resonators with a Sub-10 nm Gap

Cited by 48 publications

References 32 publications

Terahertz Sensing Based on Metasurfaces

Terahertz Sensing Based on Metasurfaces

Labyrinth Metasurface Absorber for Ultra‐High‐Sensitivity Terahertz Thin Film Sensing

Metamaterials for Enhanced Optical Responses and their Application to Active Control of Terahertz Waves

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