Abstract-Characteristic analysis of a photoexcited tunable metamaterial absorber for terahertz waves

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  • Pibin Bing, 
   
  • Xinyue Guo, Hua
   
  •  Wang, 
   
  • Zhongyang Li, J
   
  • ianquan Yao,
   https://link.springer.com/article/10.1007%2Fs12596-019-00533-1

The absorption characteristics of a photoexcited tunable perfect metamaterial absorber (PMA) at terahertz (THz) frequencies are analyzed based on the split-ring resonators (SRRs)-dielectrics-metallic structure, which are caused by different thicknesses and dielectric constants of polyimide, cell sizes and widths of SRRs, and lengths and conductivities of the photosensitive silicon. The results manifest that the resonance frequency and absorption strength of the designed PMA can be tuned by adjusting the shape, size, thickness, and properties of the metallic structure and dielectric spacer. The simple design and wide frequency tuning range of the PMA can find potential applications in terahertz detectors, filters, switchers, and absorbers.

Abstract-Highly efficient terahertz generation from periodically poled lithium niobate

Zhongyang Li, Silei Wang, Mengtao Wang, Weishu Wang

https://link.springer.com/article/10.1007/s12596-019-00531-3

Terahertz (THz) generation from periodically poled lithium niobate with a quasi-phase-matching scheme based on cascaded difference frequency generation (DFG) processes is theoretically analyzed. The cascaded Stokes interaction processes and the cascaded anti-Stokes interaction processes are investigated from coupled wave equations. THz intensities and quantum conversion efficiencies are calculated. Compared with non-cascading DFG processes, THz intensities from 15-order cascading DFG processes are increased to 7.7. The quantum conversion efficiency of 390.85% in cascaded processes can be realized, which exceeds the Manley–Rowe limit.

Abstract-Simultaneous Generation of Two Pairs of Stokes and Terahertz Waves from Coupled Optical Parametric Oscillations with Quasi-Phase-Matching

Bin Yuan, Lian Tan, Mengtao Wang, Pibin Bing,  Sheng Yuan, Silei Wang, Yongjun Li, Zhongyang Li,

http://www.mdpi.com/2073-4352/8/8/323

We present a theoretical investigation on simultaneous generation of two pairs of Stokes and terahertz (THz) waves from coupled optical parametric oscillations (OPOs) with a quasi-phase-matching (QPM) scheme. The two pairs of Stokes and THz waves are generated by stimulated polariton scattering (SPS) from periodically-inverted GaP. By analyzing the QPM conditions of coupled OPOs we find that the two THz waves with any frequency below the transverse optical (TO) mode frequency of GaP can be simultaneously generated with a suitable pump wavelength. We calculate the photon flux densities of the two THz waves by solving the coupled wave equations. The calculation results indicate that the two THz waves can be efficiently generated with high pump intensities, particularly in lower THz frequency band. 

Abstract-Simultaneous Generation of Two Orthogonally Polarized Terahertz Waves by Stimulated Polariton Scattering with a Periodically Poled LiNbO3 Crystal

Zhongyang Li, Silei Wang, Mengtao Wang, Bin Yuan, Pibin Bing,

http://www.mdpi.com/2073-4352/8/8/304

We present a theoretical investigation of the simultaneous generation of two orthogonally polarized terahertz (THz) waves by stimulated polariton scattering (SPS) with a periodically poled LiNbO₃ (PPLN) crystal. The two orthogonally polarized THz waves are generated from SPS with A₁ and E symmetric transverse optical (TO) modes in a LiNbO₃ crystal, respectively. The parallel polarized THz wave is generated from A₁ symmetric TO modes with type-0 phase-matching of e = e + e, and the perpendicular polarized THz wave is generated from E symmetric TO modes with type-I phase-matching of e = o + o. The two types of phase-matching of e = e + eand e = o + o can be almost satisfied simultaneously by accurately selecting the poling period of the PPLN crystal. We calculate the photon flux density of the two orthogonally polarized THz waves by solving the coupled wave equations. The calculation results indicate that the two orthogonally polarized THz waves can be efficiently generated, and the relative intensities between the two orthogonally polarized THz waves can be modulated.

Abstract-Investigation of Stimulated Polariton Scattering from the B1-symmetry Modes of the KNbO3 Crystal

Zhongyang Li, Mengtao Wang, Silei Wang, Bin Yuan, Pibin Bing, Degang Xu, and Jianquan Yao

https://www.osapublishing.org/copp/abstract.cfm?uri=copp-2-1-90&origin=search

Stimulated polariton scattering from the B1-symmetry modes of a KNbO3 crystal to generate a terahertz wave (THz-wave) with a noncollinear phase-matching scheme is investigated. The frequency-tuning characteristics of the THz-wave by varying the phase-matching angle and pump wavelength are analyzed. The expression for the effective parametric gain length under the noncollinear phase-matching condition is deduced. Parametric gain and absorption characteristics of the THz-wave in KNbO3 are theoretically simulated. The characteristics of KNbO3 for a terahertz parametric oscillator (TPO) are compared to those of MgO:LiNbO3. The analysis indicates that KNbO3 is an excellent optical crystal for a TPO, to enhance the THz-wave output.

© 2018 Optical Society of Korea

Abstract-Wideband zero-index metacrystal with high transmission at visible frequencies [Invited]

Zhongyang Li, Zizhuo Liu, and Koray Aydin

https://www.osapublishing.org/josab/abstract.cfm?uri=josab-34-7-D13&origin=search

Materials with zero refractive index exhibit unprecedented optical properties including no spatial phase change and infinitely large phase velocity. Several zero-index material designs including artificial layered metallic/dielectric medium were proposed and demonstrated at microwave, terahertz, and IR wavelengths. However, realizing a zero-index material with low-losses, none-dispersion, and relatively wide bandwidth operation at visible frequencies is quite challenging due to optical losses in metals. Here, we propose and numerically demonstrate a three-dimensional zero-index metacrystal (ZIM) with low loss, low dispersion, and wide bandwidth at visible frequencies. The ZIM simply consists of periodic Ag nanocube arrays embedded inside a dielectric medium with same lattice constant in all directions. The calculated effective refractive index using a parameter retrieval method reveals a relatively wide band (∼40  nm$\sim 40\mathrm{nm}$) of near-zero index (<0.02$<0.02$) and achromatic behavior for designed metacrystal in the visible frequency. Using full-field electromagnetic (EM) simulations, we have theoretically demonstrated that the EM wave always propagates normal to the ZIM–air interface in spite of oblique incidence cases or any arbitrary wavefront of illumination. Our proposed zero-index metacrystal for visible frequencies could find use in many practical applications of wide-bandwidth and low-loss achromatic photonic devices for steering light propagation, arbitrary wavefront conversion, directional emission, and obstacle-free light guiding.

© 2017 Optical Society of America

Abstract-Characteristic analysis of a photoexcited metamaterial perfect absorber at terahertz frequencies

Pibin Bing, Shichao Huang, Zhongyang Li, Zhou Yu, Ying Lu, Jianquan Yao

http://www.worldscientific.com/doi/abs/10.1142/S0217984917502074

The absorption characteristics of a photoexcited metamaterial absorber at terahertz frequencies were analyzed in this study. Filling photosensitive semiconductor silicon into the gap between the resonator arms leads to modulation of its electromagnetic response through a pump beam which changes conductivity of silicon. Comparisons of terahertz absorbing properties which were caused by different thicknesses and dielectric constants of polyimide, cell sizes and widths of SRRs, and lengths and conductivities of the photosensitive silicon, were studied by using Finite Difference Time Domain (FDTD) from 0.4 THz to 1.6 THz. The results of this study will facilitate the design and preparation of terahertz modulator, filters and absorbers.

Abstract-Terahertz generation based on difference frequency generation by rotating fan-out poled LiNbO3

Zhongyang Li, Degang Xu, and Jianquan Yao
https://www.osapublishing.org/ao/abstract.cfm?uri=ao-55-35-10073

Theoretical analysis of terahertz (THz) generation based on difference frequency generation (DFG) by rotating fan-out poled LiNbO3 is presented. The uncertainty of poling vectors during clockwise and counterclockwise rotation of the fan-out poled LiNbO3 at the center of the crystal input face is investigated. The poling period along the propagation direction of the input pump and signal waves during clockwise and counterclockwise rotation is calculated. The dependence of THz vectors on rotation angles is numerically simulated. The relative intensities of a THz wave during clockwise rotation of the fan-out poled LiNbO3LiNbO 3 are calculated.

© 2016 Optical Society of AmericaFull Article  |  PDF Article

Abstract-Investigation of Terahertz Generation from Bulk and Periodically Poled LiTaO3 Crystal with a Cherenkov Phase Matching Scheme

Zhongyang Li, Pibin Bing, Sheng Yuan, Degang Xu, and Jianquan Yao
https://www.osapublishing.org/josk/abstract.cfm?uri=josk-19-3-297

Terahertz (THz) wave generation from bulk and periodically poled <TEX>$LiTaO_3$</TEX> (PPLT) with a Cherenkov phase matching scheme is numerically investigated. It is shown that by using the crystal birefringence of bulk <TEX>$LiTaO_3$</TEX> and a grating vector of PPLT, THz waves can be efficiently generated by difference frequency generation (DFG) with a Cherenkov phase matching scheme. The frequency tuning characteristics of the THz wave via varying wavelength of difference frequency waves, phase matching angle, poling period of PPLT and working temperature are theoretically analyzed. The parametric gain coefficient in the low-loss limit and the absorption coefficient of the THz wave during the DFG process in the vicinity of polariton resonances are numerically analyzed. A THz wave can be efficiently generated by utilizing the giant second order nonlinearities of <TEX>$LiTaO_3$</TEX> in the vicinity of polariton resonances.

© 2015 Optical Society of Korea

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Abstract-Terahertz wave parametric oscillations at polariton resonance using a MgO:LiNbO3 crystal

Zhongyang Li, Pibin Bing, Sheng Yuan, Degang Xu, and Jianquan Yao
https://www.osapublishing.org/ao/abstract.cfm?uri=ao-54-18-5645

Terahertz wave (THz-wave) parametric oscillations with a noncollinear phase-matching scheme at polariton resonance using a MgO:LiNbO3 crystal with a surface-emitted configuration are investigated. We investigate frequency tuning characteristics of a THz-wave via varying the wavelength of the pump wave and phase-matching angle. The effective parametric gain length under the noncollinear phase-matching condition is calculated. Parametric gain and absorption characteristics of a THz-wave in the vicinity of polariton resonances are analyzed.

© 2015 Optical Society of America

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