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We demonstrate THz pulse propagation on a 25-cm-long semi-cylindrical aluminum plate with low loss and negligible dispersion via whispering-gallery modes. This represents the first demonstration of these modes on a curved metallic surface in the THz regime, and is important for implementing curved waveguides based on parallel metal plates.
We demonstrate a 2D artificial dielectric medium, fabricated using a parallel-plate waveguide configuration, whose refractive index varies from close to unity down to zero in the THz region.
We report on dynamic properties of supported phospholipid membranes, using a spectroscopy technique based on terahertz surface guided waves. The transmitted spectra clearly show not only signal decrease of about 10% due to water absorption, but also transmission dips caused by the vibrational motions of membrane molecules.
We investigate the temperature dependent absorption characteristics of polyamides (PA) in the terahertz frequency range. The absorption spectra can be explained by inter-molecular bonding mechanisms. Experimental data is obtained by terahertz time-domain spectroscopy (THzTDS) on injection-molded specimens as well as on molten polyamides at different temperatures. The THzTDS data is compared to FTIR...
Using a recently developed scattering-probe-imaging technique, we observe strong confinement of the THz electric field at the end of a tapered metal-wire waveguide compared to an un-tapered wire. This confinement agrees well with FEM simulations.
We characterize the operation of a 4times4 electrically-driven terahertz metamaterial spatial modulator, and demonstrate high modulation uniformly at each pixel with minimal cross-talk. This modulator will enable high-speed terahertz imaging in a single-pixel imaging system.
We demonstrate the spectral properties of resonant transmission induced by perpendicularly polarized light through an individual hole in a thin metallic film, using time-domain terahertz spectroscopy. Our measurements and intuitive understanding show that the resonance is activated by a coupling between the perpendicular component of incident light and existing antibonding film plasmon modes.
We present results from our investigation into the liquid-lattice structures of n-pentane (C5H12) through n-hexadecane (C16H34). We observe alternating absorption values, at single frequencies, which are surprising and provide information about long-range correlations in liquids.
We investigate the TEM-mode energy confinement in finite-width parallel-plate waveguides using THz pulses, and observe a narrowing of the mode profile due to the finite width, although this does not result in better energy confinement.
We demonstrate THz-pulse propagation on a 25-cm-long semi-circular aluminum plate with low loss and negligible dispersion via whispering-gallery-modes. This represents the first demonstration of these modes on a curved metallic surface in the THz regime.
We describe an experimental and theoretical study of the lowest-order transverse-electric (TE1) mode of the parallel-plate waveguide for the propagation of broadband THz pulses, and demonstrate undistorted THz pulse propagation via the TE1 mode. This demonstration overcomes two fundamental problems associated with the low-frequency cutoff of this mode, the group velocity dispersion and the spectral...
We observe dramatic changes in the spectrum of radiation scattered from a near-field tip with decreasing tip-sample distance. This arises from a balance between direct tip scattering and signals associated with the near-field image dipole.
We observe terahertz vibrational modes in crystals of n-octadecane, a non-hydrogen-bonding, non-polar molecule. These modes are not present in amorphous samples.
We describe a single-pixel, pulsed terahertz camera which uses random patterns to enable high-speed image acquisition. Our method requires no raster scanning of objects, nor detection using a focal-plane array.
We demonstrate fully flexible, high performance terahertz Bragg reflectors and filters based on TiO2-loaded polymers. Broadband terahertz reflection measurements with corresponding transfer matrix simulations are shown and the effect of curvature is analyzed.
We present terahertz transmission time-domain spectroscopy measurements on a variety of additive-polymer combinations with differing additive contents. At lower terahertz frequencies, standard polymers are transparent. When processed into compounds, their terahertz properties are distinctively affected by additives in most cases. The materials under investigation are magnesium hydroxide in linear...
Using terahertz apertureless near-field microscopy, we observe an electromagnetic field enhancement produced by a broadband plasmon resonance localized in the junction between a metal probe tip and a sub-micron-thick metallic substrate.
We describe a new terahertz imaging method for high-speed image acquisition using a compressed sensing phase retrieval algorithm. This technique permits image reconstruction using a limited and randomly chosen subset of a Fourier image.
We investigate the photoconductivity of regioregular poly(3-hexylthiophene) using 400 and 800 nm light. We observe a linear dependence of the photocurrent on optical power at both wavelengths.
We report temperature and magnetic field dependent terahertz time domain spectroscopy measurements on InMnAs. The temperature dependent transmission is shown to vary with Mn content and applied magnetic field strength.
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