Regensburg 2022 – scientific programme
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MA: Fachverband Magnetismus
MA 21: Terahertz Spintronics
MA 21.3: Talk
Wednesday, September 7, 2022, 10:00–10:15, H43
Coupling of a local broadband THz emitter to a 2D micro-resonator — •Christopher Rathje1, Rieke von Seggern1, Leon Gräper1, Jana Kredl2, Jakob Walowski2, Markus Münzenberg2, and Sascha Schäfer1 — 1Institut für Physik, Universität Oldenburg — 2Institut für Physik, Universität Greifswald
Recently, the advent of spintronic terahertz emitters (STE) has introduced a simple approach to generate broadband radiation in the terahertz (THz) spectral domain [1].
In this contribution, we utilize a resonator-grafted STE bilayer illuminated by a focused optical excitation pulse for the generation of a micrometer-scaled broadband THz emitter with a source size far below the THz diffraction limit [2]. The near-field of this localized transient electric dipole is coupled to a bow-tie antenna structure in direct proximity to the emitter. Depending on the position of the excitation focus, we detect the emitted THz time-domain signal in the far-field.
Our results show pronounced changes of the emission characteristics of the excited STE layer for a dipole positioned in the bow-tie gap, demonstrating the capability to tailor the emission spectrum including resonant enhancement of certain frequency components and increase of the overall bandwidth. We discuss the influence of different resonator designs and provide a model of the coupling process supported by numerical simulations. Further results for different isolated resonators and periodically structured metasurfaces are presented.
[1] Seifert et al., Nat. Photonics, 10, 483 (2016)
[2] Rathje et al., manuscript in preparation