Erlangen 2022 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 41: Nano-Optics
Q 41.15: Poster
Wednesday, March 16, 2022, 16:30–18:30, P
Direct writing of chiral and nonlinear plasmonic devices — •Aleksei Tsarapkin1, Thorsten Feichtner2, and Katja Hoeflich1 — 1Ferdinand-Braun-Institut gGmbH, 12489 Berlin, Germany — 2Politecnico di Milano, 20133 Milano, Italy
The miniaturization of electrical and optical components allowed many technological and economic advancements over the last decades. Devices that permit control over the polarization of light are crucial in telecommunication and quantum optics but are usually realized as bulky optical systems and thus require further miniaturization. Here we aim at designing a uniquely compact converter and detector based on plasmonics. The structure consists of a vertically oriented gold double helix coupled to a planar two-wire transmission line. The helix acts as a sensitive antenna for circularly polarized light, while the plasmonic transmission line exhibits two different modes depending on the incident polarization state and guides them on-chip. FEM and FDTD analysis show that antisymmetric modes can be excited in both double helix and two-wire waveguide. Furthermore, one can adjust the geometry of these structures to optimize coupling strength and finely tune their optical response to the desired wavelength range. Finally, we developed fabrication protocols: while the helices can be directly written with an electron-induced deposition, the plasmonic waveguides can be cut from single-crystalline gold flakes utilizing focused gallium-ion beam milling. We achieved high structuring resolution with both methods, allowing for efficient coupling to transform linear to circular polarization while retaining a device size of just a few microns.