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We present an electrically modulated nonlinear metamaterial at terahertz frequencies. The device consists of a planar array of split-ring resonators (SRRs) fabricated on n-type GaAs. Increasing the incident THz field strength induces carriers in the GaAs substrate, shorting the SRR capacitive gap and modulating the MM resonance. The application of a 15V bias to the MM reduces the net field modulation...
We have used ultrafast THz spectroscopy to both excite and probe low energy excitations in two-dimensional electron gases, topological insulators, and multiferroics.
We describe experimental characterization of switchable terahertz metasurfaces using broadband ellipsometry. A theoretical framework based on generalized sheet transition conditions is developed to extract surface susceptibility as a function of frequency and applied DC bias. This will allow us to make a priori predictions of the performance of these switchable devices in device applications, enabling...
We experimentally and numerically investigate a switchable dielectric-slab-waveguide metasurface device. We use an active metasurface to manipulate the interaction with a propagating THz surface wave, giving us dynamic control of the wave at 0.3 THz.
We design and test a switchable diffraction grating based on active metamaterials for terahertz modulation. We observe off-axis diffraction which permits operation of the device as a high-contrast modulator, with better than 20 dB of dynamic range.
Split-ring-resonators (SRR) play a significant role in the design and realization of metamaterials over a wide range of the electromagnetic spectrum. In addition to single SRR layers, a number of demonstrations have been carried out to understand the bulk properties of multiple layer structures. Usually, the SRR layers are separated by dielectrics with a layers spacing > λres/30. We present the...
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