Giant Photoresponsivity of Midinfrared Hyperbolic Metamaterials in the Photon-Assisted-Tunneling Regime

Chen, Pai Yen; Hajizadegan, Mehdi; Sakhdari, Maryam; Alù, Andrea

doi:10.1103/physrevapplied.5.041001

Cited by 19 publications

(26 citation statements)

References 49 publications

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“…Figures 7(a, b) prove that the period and width of the graphene sheets and air slots, respectively, have distinct effects on the amplification of the THz waves. The gain is presented in dB scale and computed by 10 ( ) 10log (| |)…”

Section: Simulation Resultsmentioning

confidence: 99%

Tunable terahertz amplification based on photoexcited active graphene hyperbolic metamaterials [Invited]

Guo¹,

Zhu²,

Chen³

et al. 2018

Opt. Mater. Express

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The efficient amplification and lasing of electromagnetic radiation at terahertz (THz) frequencies is a nontrivial task achieved mainly by quantum cascade laser configurations with limited tunability and narrowband functionality. There is a strong need of compact and efficient THz electromagnetic sources with reconfigurable operation in a broad frequency range. Photoexcited graphene can act as the gain medium to produce coherent radiation at low THz frequencies but its response is very weak due to its ultrathin thickness. In this work, we demonstrate an alternative design to achieve efficient tunable and compact THz amplifiers and lasers with broadband operation based on active THz hyperbolic metamaterials (HMM) designed by multiple stacked photoexcited graphene layers separated by thin dielectric sheets. The hyperbolic THz response of the proposed ultrathin active HMM is analytically and numerically studied and characterized. When the graphene-based HMM structure is periodically patterned, a broadband slow-wave propagation regime is identified, thanks to the hyperbolic dispersion. In this scenario, reconfigurable amplification of THz waves in a broad frequency range is obtained, which can be made tunable by varying the quasi-Fermi level of graphene. We demonstrate that the THz response of the presented tunable THz amplifiers or lasers is controlled by the incident optical pumping (photodoping) and the loaded dielectric materials in the HMM waveguide array, an interesting property that can have great potential for THz amplification, emission, and sensing applications.

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Section: Simulation Resultsmentioning

confidence: 99%

Tunable terahertz amplification based on photoexcited active graphene hyperbolic metamaterials [Invited]

Guo¹,

Zhu²,

Chen³

et al. 2018

Opt. Mater. Express

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“…Hyperbolic metamaterials (HMM) have recently attracted intense scientific interest in controlling the propagation, scattering, and radiation of light. To date, HMMs have found numerous applications in negative refraction [1,2], superlensing [3], biosensing [4], perfect absorbers [5], energy harvesting [5,6], and enhancement of spontaneous emission [7] or Purcell effect [8]. HMM are anisotropic and uniaxial artificial materials which are usually constructed by either metal-dielectric multilayers or metallic nanorod arrays [3].…”

Section: Introductionmentioning

confidence: 99%

Tunable THz generation and enhanced nonlinear effects with active and passive graphene hyperbolic metamaterials

Jin

Guo

Zhu

et al. 2020

Smart Photonic and Optoelectronic Integrated Circuits XXII

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The active and nonlinear graphene properties are limited due to weak light-matter interaction between the ultrathin graphene and the incident light. In this work, we present enhanced nonlinear effects at the low terahertz (THz) range by designing a new patterned graphene hyperbolic metamaterial (GHMM). More specifically, it is demonstrated that the third harmonic generation (THG) can be significantly enhanced by the proposed GHMM due to the field enhancement at the resonance as well as the supported slow-light response that fosters strong light-matter interaction.

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“…In this way, superresolution pictures are formed in the far field. The hyperlens can be constructed by periodic arrangement of plasmonics materials and common dielectrics [11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…A remarkable device, termed hyperlens, is capable of converting the evanescent harmonics into propagating waves through curved geometry [13][14][15][16] or gratings [17,18].In this way, superresolution pictures are formed in the far field. The hyperlens can be constructed by periodic arrangement of plasmonics materials and common dielectrics [11][12][13][14][15][16][17][18][19][20].When it comes to the longer wavelength, for example, the terahertz domain, which has great potential in non-destructive testing and manufacturing quality control, the metal behaves as perfect electric conductor [21,22]. To mimic the intriguing properties of natural plasmonic effect, by texturing the geometrical features of high-conductivity metal, the concept of spoof surface plasmons (SSP) [23] is developed with low loss and high flexibility.…”

mentioning

confidence: 99%

Far-Field Subwavelength Resolution Imaging by Spatial Spectrum Sampling

et al. 2019

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Imaging below the diffraction limit is always a public interest because of the restricted resolution of conventional imaging systems. To beat the limit, evanescent harmonics decaying in space must participate in the imaging process. Here, we introduce the method of spatial spectrum sampling, a novel far-field superresolution imaging method for microwave and terahertz regime. Strong dispersion and momentum conservation allow the spoof surface plasmon polaritons (SSP) structure to become a sensitive probe for spatial harmonics. This enables that the spatial information of the targets including both propagating and evanescent components, can be extracted by tuning and recording SSP in the far field. Then, the subwavelength resolution is constructed by the inversed Fourier transform of the sampled spatial spectrum. Using the modified subwavelength metallic grating as the probe, a far-field resolution of 0.17 is numerically and experimentally verified, and two-dimensional imaging ability is also fully discussed. The imaging ability and flexibility can be further optimizing the SSP structures.We are confident that our working mechanism will have great potentials in the superresolution imaging applications in the microwave and terahertz frequency range. IntroductionAchieving spatial resolution without limited by the working wavelength always attracts tremendous attention, due to the pervasive applications of imaging. However, the diffraction limit indicates the fine features smaller than half a wavelength are carried by the evanescent harmonics [1], whose amplitude exponentially decays with distance. The contribution of these harmonics is negligible when the imaging distance larger than a wavelength. To circumvent the inherent limitation, the optical elements should own ability of capturing the evanescent part of spatial information. By mechanically canning a sensitive probe, the near-field microscope (NFSM) [2-4] can well surpass the diffraction limit for thousand times, but the imaging operation is very time-wasting. To obtain superresolution images in a single shot, the concept of perfect lens is theoretically exploited by Pendry [1], utilizing the plasmonic effect in materials to enhance the evanescent waves [5,6]. Soon after this imaging method is experimentally verified at optical wavelength by plasmonic slabs, such as the noble metal [7,8] and dielectrics [9]. Although the imaging ability of such lenses can be further enhanced by other methods [10], the working distance is still subject to the near field [11,12]. A remarkable device, termed hyperlens, is capable of converting the evanescent harmonics into propagating waves through curved geometry [13][14][15][16] or gratings [17,18].In this way, superresolution pictures are formed in the far field. The hyperlens can be constructed by periodic arrangement of plasmonics materials and common dielectrics [11][12][13][14][15][16][17][18][19][20].When it comes to the longer wavelength, for example, the terahertz domain, which has great potential in non-destructive test...

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Giant Photoresponsivity of Midinfrared Hyperbolic Metamaterials in the Photon-Assisted-Tunneling Regime

Cited by 19 publications

References 49 publications

Tunable terahertz amplification based on photoexcited active graphene hyperbolic metamaterials [Invited]

Tunable terahertz amplification based on photoexcited active graphene hyperbolic metamaterials [Invited]

Tunable THz generation and enhanced nonlinear effects with active and passive graphene hyperbolic metamaterials

Far-Field Subwavelength Resolution Imaging by Spatial Spectrum Sampling

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