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(a) Schematic representation of the 1D CRLH metamaterial waveguide with staggered gap capacitors incorporated in the top metallization and its equivalent transmission-line model. The lumped element values in the circuit diagram are chosen such that each unit cell has total values of CR , CL , LR , and LL . (b) The dispersion characteristic obtained by full-wave finite element simulations of one unit cell. Inset shows eigenmode quality factors due to radiation loss only ( ), and radiation and ohmic metallic losses ( ). A finite-conductivity Au metallization was employed in simulations using a Drude model with , fs, .
Scanning electron microscope (SEM) image of the fabricated CRLH antenna-coupled device fed by a THz QC-laser source, and close-up of the meander-type CRLH metamaterial waveguide with staggered gap capacitors in its top metallization.
Backwards beam scanning with frequency (polar representation). Data were collected in pulsed mode (400 ns pulses repeated at 10 KHz) with the QC-laser and the CRLH antenna biased synchronously. Inset shows the spectra of the two backward beams corresponding to excitation frequencies 2.484 THz (blue) and 2.594 THz (red).
(a) Pulsed L-I-V for the −60° beam at 4 K. Peak THz power was measured using a thermopile detector in the surface direction for the antenna structure with no collection optics in the cryostat but mounted at an angle (+60°) with respect to the cryostat window. A superlinear fit to the LI curve is also plotted with mA, mA, and mA. (b) 1D cuts of beam pattern in the surface direction along the longitudinal direction at various bias currents. Inset shows the spectrum of radiation.
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