Nanoplasmonics in Metallic Nanostructures and Dirac Systems

Paudel, Hari P.; Safaei, Alireza

doi:10.5772/67689

Cited by 11 publications

(19 citation statements)

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“…The localized surface plasmon resonance (LSP) frequency of the hole can be determined from the equation the condition for which the denominator of α || vanishes. Using the linear dispersion relation, the intraband optical conductivity is 11,12 which in the case of ε F ≫ k B T is reduced to where τ is determined by impurity scattering and electron-phonon interaction τ −1 = τ −1 imp + τ −1 e−ph . Using the mobility µ of the NPG sheet, it can be presented in the form τ −1 = ev 2 F /(µE F ) , where v F = 10 6 m/s is the Fermi velocity in graphene.…”

Section: Lsp Of a Hole In Graphenementioning

confidence: 99%

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Plasmonically enhanced mid-IR light source based on tunable spectrally and directionally selective thermal emission from nanopatterned graphene

Shabbir

2020

Sci Rep

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We present a proof of concept for a spectrally selective thermal mid-IR source based on nanopatterned graphene (NPG) with a typical mobility of CVD-grown graphene (up to 3000 $$\hbox {cm}^2\,\hbox {V}^{-1}\,\hbox {s}^{-1}$$ cm 2 V - 1 s - 1 ), ensuring scalability to large areas. For that, we solve the electrostatic problem of a conducting hyperboloid with an elliptical wormhole in the presence of an in-plane electric field. The localized surface plasmons (LSPs) on the NPG sheet, partially hybridized with graphene phonons and surface phonons of the neighboring materials, allow for the control and tuning of the thermal emission spectrum in the wavelength regime from $$\lambda =3$$ λ = 3 to 12 $$\upmu$$ μ m by adjusting the size of and distance between the circular holes in a hexagonal or square lattice structure. Most importantly, the LSPs along with an optical cavity increase the emittance of graphene from about 2.3% for pristine graphene to 80% for NPG, thereby outperforming state-of-the-art pristine graphene light sources operating in the near-infrared by at least a factor of 100. According to our COMSOL calculations, a maximum emission power per area of $$11\times 10^3$$ 11 × 10 3 W/$$\hbox {m}^2$$ m 2 at $$T=2000$$ T = 2000 K for a bias voltage of $$V=23$$ V = 23 V is achieved by controlling the temperature of the hot electrons through the Joule heating. By generalizing Planck’s theory to any grey body and deriving the completely general nonlocal fluctuation-dissipation theorem with nonlocal response of surface plasmons in the random phase approximation, we show that the coherence length of the graphene plasmons and the thermally emitted photons can be as large as 13 $$\upmu$$ μ m and 150 $$\upmu$$ μ m, respectively, providing the opportunity to create phased arrays made of nanoantennas represented by the holes in NPG. The spatial phase variation of the coherence allows for beamsteering of the thermal emission in the range between $$12^\circ$$ 12 ∘ and $$80^\circ$$ 80 ∘ by tuning the Fermi energy between $$E_F=1.0$$ E F = 1.0 eV and $$E_F=0.25$$ E F = 0.25 eV through the gate voltage. Our analysis of the nonlocal hydrodynamic response leads to the conjecture that the diffusion length and viscosity in graphene are frequency-dependent. Using finite-difference time domain calculations, coupled mode theory, and RPA, we develop the model of a mid-IR light source based on NPG, which will pave the way to graphene-based optical mid-IR communication, mid-IR color displays, mid-IR spectroscopy, and virus detection.

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Section: Lsp Of a Hole In Graphenementioning

confidence: 99%

“…Using the general formula with in the low-temperature and low-frequency approximation, one obtains Eq. (12). Now, let us use the full polarization in RPA approximation including only the Coulomb interaction, from which we obtain Figure 6.…”

Section: Partial Coherence Of Plasmons In Graphene and The Grey-body mentioning

confidence: 99%

Plasmonically enhanced mid-IR light source based on tunable spectrally and directionally selective thermal emission from nanopatterned graphene

Shabbir

2020

Sci Rep

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“…Strong interaction between the incident light beam and surface plasmon leads to an abrupt phase change of the scattered electric field. [5,13,15,16,19,[29][30][31][32][33][34][35][36][37][38] Excitation of surface plasmons is due to the charge oscillation on the metallic elements driven by the incident electric field, and at the plasmon resonance frequency, the driving optical field is in phase with the induced current. The change in the length of the nanostructure gives rise to the change in the resonance frequency, and consequently, the excited current leads or lags the incident field.…”

Section: Introductionmentioning

confidence: 99%

High‐Efficiency Broadband Mid‐Infrared Flat Lens

Safaei

Vázquez‐Guardado

Franklin

et al. 2018

Advanced Optical Materials

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wavelength of incoming light to accumulate 0 to π phase shifts. That means subwavelength compact planar geometry is not possible in conventional lenses making optical systems bulky. Furthermore, conventional lenses are limited by optical aberrations (e.g., spherical and chromatic) and diffraction limit. [1] The Abbe-Rayleigh diffraction limit is a natural obstacle in conventional optical lenses due to the far-field interference and absence of near-field. [2] Various planar lenses have been demonstrated following the diffractive optics concept of phase control based on dielectric scatterers on a 2D plane. [3][4][5][6][7][8][9] However, in the mid-infrared wavelength range (3-16 µm), such engineered dielectric surfaces are elusive due to the low spectral bandwidth [8,9] and high thermal noise in long wavelengths. [10,11] In contrast, plasmonic nanoantennas [12][13][14][15][16][17] enable abrupt change in phase, amplitude, and polarization of the incident light using subwavelength optical scatterers on a planar surface. Such control of phase according to the Huygens principle [18] allows the formation of arbitrary wavefront shapes enabling subwavelength focusing. [3][4][5] Spatially distributed plasmonic nanoantennas suppress higher diffraction orders and concentrate the incident light beam beyond the Abbe-Rayleigh diffraction limited focal point. [19][20][21][22] In addition, possibility of the optical impedance matching with the free space by the patterned plasmonic interface reduces back scattering, leading to higher transmission efficiency. [5,23] Going beyond the Abbe-Rayleigh diffraction limit requires the involvement of evanescent fields with large spatial frequency components which is possible by plasmonic nanoantennas, enabling subwavelength resolution capability going beyond the current imaging technologies. [2,14,22,24,25] Here, we propose and experimentally demonstrate an ultrathin flat lens working in the mid-IR spectral range with geometrically tunable focal length and subwavelength focusing ability. The transmission efficiency of this flat lens is substantially higher compared with other reported plasmonic lenses due to the low metallic fill-fraction and the geometry. [14][15][16]26,27] The biggest limitation of dielectric as well as metallic flat lenses is the bandwidth of operation due to the inherent narrowband resonance. [8,9] Previously, reported plasmonic flat lenses were limited to λ ≈ 1.0-1.9 µm, [15] ≈5.2-9.9 µm, [16] and λ ≈ 5-10 µm, [14] operation bandwidths in the infrared spectral range. None of these works reported the most critical lens Integrated photonic circuits and infrared imaging systems demand compact optical components. Dielectric diffractive optics enables miniaturization of the curved refractive optics into planar structure by encoding phase over a 2D plane. However, in the mid-infrared wavelength range, such engineered dielectric surfaces are not efficient, because optically transparent dielectric scatterers with high index contrast in the mid-infrared spectral range suffer f...

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“…Surface plasmon is collective oscillation of electrons on metal-insulator interface excited by an electromagnetic wave; the surface plasmons can be either in the propagating (surface plasmon polariton SPP) or localized surface plasmon (LSP) mode [1,2]. The fundamental order of LSP, the dipolar excitation, has the highest strength and its properties, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…This dependence gives a way to control and tailor the surface plasmon resonances to desired frequencies. Surface plasmons have the potential to be used in integrated photonic circuits [1,7], SERS measurements [4], flat optics [8], hot-electron injected sensors [1,7] and metamaterials with properties such as near-zero [9], negative [10] and hyperbolic [11] index of refraction. The prime difficulty in bringing these concepts to full-fledged applications is the large plasmon decay rate mainly due to the finite metal conductivity that decreases the lifetime of the excited surface plasmon and induce losses in the form of heat dissipation [12,13].…”

Section: Introductionmentioning

confidence: 99%

Multi-spectral frequency selective mid-infrared microbolometers

Safaei¹,

Modak²,

Lee³

et al. 2018

Opt. Express

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Frequency selective detection of low energy photons is a scientific challenge using natural materials. A hypothetical surface which functions like a light funnel with very low thermal mass in order to enhance photon collection and suppress background thermal noise is the ideal solution to address both low temperature and frequency selective detection limitations of present detection systems. Here, we present a cavity-coupled quasi-three dimensional plasmonic crystal which induces impedance matching to the free space giving rise to extraordinary transmission through the sub-wavelength aperture array like a "light funnel" in coupling low energy incident photons resulting in frequency selective perfect (~100%) absorption of the incident radiation and zero back reflection. The peak wavelength of absorption of the incident light is almost independent of the angle of incidence and remains within 20% of its maximum (100%) up to i θ 45 ≤ . This perfect absorption results from the incident light-driven localized edge "micro-plasma" currents on the lossy metallic surfaces. The wide-angle light funneling is validated with experimental measurements. Further, a super-lattice based electronic biasing circuit converts the absorbed narrow linewidth (0 / Δ < λ λ 0.075) photon energy inside the sub-wavelength thick film (< λ/100) to voltage output with high signal to noise ratio close to the theoretical limit. Such artificial plasmonic surfaces enable flexible scaling of light funneling response to any wavelength range by simple dimensional changes paving the path towards room temperature frequency selective low energy photon detection.

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Nanoplasmonics in Metallic Nanostructures and Dirac Systems

Cited by 11 publications

References 153 publications

Plasmonically enhanced mid-IR light source based on tunable spectrally and directionally selective thermal emission from nanopatterned graphene

Plasmonically enhanced mid-IR light source based on tunable spectrally and directionally selective thermal emission from nanopatterned graphene

High‐Efficiency Broadband Mid‐Infrared Flat Lens

Multi-spectral frequency selective mid-infrared microbolometers

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