Xinchao Lu

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We experimentally demonstrate a chiral metamaterial exhibiting negative refractive index at terahertz frequencies. The presence of strong chirality in the terahertz metamaterial lifts the degeneracy for the two circularly polarized waves and allows for the achievement of negative refractive index without requiring simultaneously negative permittivity and(More)
We demonstrate the realization of a two-dimensional chiral optical waveguide with an infinite translational symmetry that exhibits asymmetric wave propagation. The low-symmetry geometry of the cross-section that lacks any rotational and mirror symmetries shows in-principal directional asymmetric polarization rotation. We use general symmetry arguments to(More)
Both the localized resonance and excitation of spoof surface plasmon polaritons are observed in the terahertz transmission spectra of periodic subwavelength hole arrays. Analyzing with the coupled oscillator model, we find that the terahertz transmission is actually facilitated by three successive processes: the incident terahertz field first initiates the(More)
We demonstrate a metamaterials-based THz broadband polarization rotator which is able to rotate linearly polarized THz wave by 90 degree within a wide frequency range (0.44 to 0.76 THz). The device is characterized both theoretically and experimentally. Analyses show that the multiple-plasmon-resonance is the key for the broadband feature and the(More)
We have investigated the broadband terahertz (THz) optical properties of nanoporous silicon samples with different porosities and the ultrafast carrier dynamics of photogenerated charge carriers in these materials. Following photoexcitation, we observe a fast carrier recovery time consisting of two dominant recombination processes with decay constants below(More)
We present a systematic numerical study of a metal-dielectric-metal sandwich plasmonic structure for broadband resonant transmission at terahertz frequencies. The proposed structure consists of periodic slotted metallic arrays on both sides of a thin dielectric substrate and is demonstrated to exhibit a broad passband transmission response. Various design(More)
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