Imaging of terahertz surface plasmon waves excited on a gold surface by a focused beam

Abstract

Surface plasmon polariton (SPP) waves formed near a tightly focused THz beam on a metallic surface are detected by an integrated sub-wavelength aperture THz near-field probe. The probe allows mapping the electric field pattern of the SPP wave and tracking the SPP propagation from the center of the focal spot. The SPP nature of the observed wave is confirmed by time-resolved measurements. Analysis of the detected patterns leads to an explanation of how THz SPP waves can be detected by the integrated sub-wavelength aperture probe.

Near-Field Analysis of Terahertz Pulse Generation From Photo-Excited Charge Density Gradients

“…Radiation from a dipole oriented within the surface plane is expected to couple into the probe most efficiently if it is aligned with the aperture center. Radiation from a dipole oriented perpendicular to the surface on the other hand couples into the probe only if the dipole is positioned to the left or to the right of the aperture center [21]. Therefore we expect different near-field signatures for the two orthogonal current directions.…”

“…For each position, the simulated voltage across the gap of the antenna is recorded in time, providing a spacetime map of the radiated field, as in the experiment. The simulation of the probe geometry ensures that the numerical results can be compared directly to the experiment despite the fact that these maps display a signal, which combines two electric field components, E x and E z [21,22].…”

“…The waveform however displays the typical response of the 50 µm aperture with a spectral peak near the aperture cut-off frequency [Figs. 7(c) and 7(d)] [21].…”

Numerical analysis of terahertz surface plasmon polaritons propagating in a parallel plate configuration

“…By optimizing the width and separation, THz waves have been confined down to a size of 10 µm (≈λ/260). Mueckstein and Mitrofanov [11] have studied THz surface plasmon waves excited on a gold surface by a focused beam. Jeon and Grischkowsky [12] have experimentally studied the propagation of THz Zenneck surface wave on an aluminium sheet, which are basically THz surface plasmons.…”

Surface Plasmon Wave Manipulated by Quantum Coherence of Multilevel Quantum Dots

“…Since surface plasmon excitation and SPR (surface plasmon resonance) polaritons can exhibit a strong interaction with nanoscopic objects, and would have many intriguing applications for designing new micro-and nano-scale photonic devices [1][2][3], recently the SPR optics have captured much interest in photonics, electronics and related technologies [4][5][6][7][8][9]. In the literature, an effect called ATR (attenuated total reflection), where surface plasmon resonance is involved, has been observed in Otto and Kretschmann's configurations (prism couplers) [10][11][12].…”