Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 21: Poster I
MA 21.48: Poster
Dienstag, 13. März 2018, 09:30–13:00, Poster A
Determining the spotsize of a microlense to build a THz emitter — •Nina Meyer1, Finn Lietzow1, Jakob Walowski1, Christian Denker1, Tom Seifert2, Tobias Kampfrath2, and Markus Münzenberg1 — 1Institute of Physics, Greifswald University, Greifswald, Germany — 2Fritz Haber Institut, MPG, Berlin, Germany
So far Terahertz (THz) spectroscopy has been used as a characterization method, since the intermolecular bonding energies of larger molecules (4 to 400 meV) are in the THz range (1 to 100 THz). The excitation energy for phonons or plasmons in solids lies in the same range. Therefore, THz radiation can be used for probing and driving such low-energy excitations. To lower costs and to simplify analysis smaller THz emitters and detectors are needed. Here we present our first attempts towards micrometer sized spintronic THz emitters. We start with fabricating microlenses on glass substrates using 3D 2-photon-lithography. By this we were able to focus a 1560 nm laser beam with 100 fs pulselength on a CMOS Chip. We measured a spotsize smaller than 10 µm at the focus length for a microlens with a radius of 300 µm. We also fabricated microlenses on a fiber to guide the laser beam directly onto the microlens. The next step is to use the microlens on a fiber to generate THz radiation. To accomplish this, we are going to include a thin film of a ferromagnetic layer and a non-magnetic cap layer. By focusing a femtosecond laser pulse onto the thin film THz radiation is generated. For large scales, this approach has been demonstrated by Seifert et al. [1].
[1] T. Seifert et al., Nat. Photon. 10 (2016) 483.