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Epsilon-near-zero phase-matching for second-harmonic generation in semiconductor-based nanowire hyperbolic metamaterial
(2023-01-01)
Wicharn, Surawut
;
Buranasiri, Prathan
Hyperbolic metamaterials have been widely used for nonlinear optical applications. Their unique functionality for nonlinear optics enhancement due to the hyperbolic dispersion is induced by a strong shape anisotropy. In this work, we numerically investigated the second-harmonic generation (SHG) in two-dimensional periodic arrays of aluminium gallium arsenide (AlGaAs) nanowires embedded in ordered porous aluminum oxide (Al2O3) or the nanowire hyperbolic metamaterial (NHMM). Under local effective medium approximation, the homogenization of the NHMM was achieved due to deep sub-wavelength size of each nanowire radius. Then this medium was classified as an effective uniaxial medium with anisotropic electric permittivity. The NHMM provided the spectral position of second-harmonic (SH) wavelength, which is determined at the epsilon-near-zero (ENZ) by the optimal design of NHMM structural parameters such as AlGaAs radius or fill fraction. Consequently, a gigantic increment of SHG conversion efficiency was achieved because of dramatic phase-matching at ENZ point. This mechanism is attributed to electric field enhancement of SHG inside the metamaterial. According to numerical results, the NHMM can be applied as nonlinear frequency converters in integrated nanophotonic systems.
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Wide-Angle Dual-Band Absorber Based on Nanowire-Hyperbolic Medium
(2021-03-10)
Wicharn, Surawut
;
Plaipichit, Suwan
;
Buranasiri, Prathan
We proposed a dual-band absorber in the visible regime by using nanowire-hyperbolic medium, which is composed of an array of subwavelength-sized hybrid nanowires immersed in dielectric matrix, as a top layer, silicon dioxide as a middle layer, and gold as a bottom layer. Each nanowire is made by core-shell structure, which has silicon as a core and gold as a shell. We found that the dual-band absorption originated from impedance matching between incident medium impedance and input impedance of the proposed absorber at first-and second-order resonant modes. Furthermore, the absorbance can be controlled by adding or reducing filling factor of hyperbolic medium layer. In addition, the absorption performance of the absorber retains well in wide angles. This dual-band absorber is a good candidate for potential applications such as thermal radiation tailoring and sensitive detection.
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Quasibirefringent phase-matching technique for third-harmonic pulse generation from multilayered metamaterials
(2018-11-01)
Wicharn, Surawut
;
Buranasiri, Prathan
A phase-matched third-harmonic (TH) generation from multilayered metamaterials (MMs) with a third-order nonlinearity is numerically investigated in the ultrashort pulse regime. To overcome the phase-mismatch problem due to natural material dispersion, we propose a solution based on engineered dispersion provided by MMs with hyperbolic dispersion, i.e., with anisotropic materials possessing a positive and negative dielectric permittivity. We analyzed selected material choices and demonstrated quasibirefringent phase-matched conditions for TH conversion, which could be achieved by optimizing the fill-factor of metamaterials. We study the conversion efficiencies of transmitted and reflected TH pulses as a function of incident angles and input fundamental-frequency intensity; the maximum efficiencies are obtained for optimal incident angles.

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