Universität Stuttgart
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Item Open Access Tailored nanocomposites for 3D printed micro-optics(2020) Weber, Ksenia; Werdehausen, Daniel; König, Peter; Thiele, Simon; Schmid, Michael; Decker, Manuel; Oliveira, Peter William de; Herkommer, Alois; Giessen, HaraldItem Open Access Mass-producible micro-optical elements by injection compression molding and focused ion beam structured titanium molding tools(2020) Ristok, Simon; Roeder, Marcel; Thiele, Simon; Hentschel, Mario; Guenther, Thomas; Zimmermann, André; Herkommer, Alois; Giessen, HaraldItem Open Access Generation of terahertz radiation via the transverse thermoelectric effect(2023) Yordanov, Petar; Priessnitz, Tim; Kim, Min‐Jae; Cristiani, Georg; Logvenov, Gennady; Keimer, Bernhard; Kaiser, StefanTerahertz (THz) radiation is a powerful tool with widespread applications ranging from imaging, sensing, and broadband communications to spectroscopy and nonlinear control of materials. Future progress in THz technology depends on the development of efficient, structurally simple THz emitters that can be implemented in advanced miniaturized devices. Here, it is shown how the natural electronic anisotropy of layered conducting transition metal oxides enables the generation of intense terahertz radiation via the transverse thermoelectric effect. In thin films grown on off‐cut substrates, femtosecond laser pulses generate ultrafast out‐of‐plane temperature gradients, which in turn launch in‐plane thermoelectric currents, thus allowing efficient emission of the resulting THz field out of the film structure. This scheme is demonstrated in experiments on thin films of the layered metals PdCoO2 and La1.84Sr0.16CuO4, and model calculations that elucidate the influence of the material parameters on the intensity and spectral characteristics of the emitted THz field are presented. Due to its simplicity, the method opens up a promising avenue for the development of highly versatile THz sources and integrable emitter elements.Item Open Access Effects of high-power laser radiation on polymers for 3D printing micro-optics(2023) Klein, Sebastian; Ruchka, Pavel; Klumpp, Thomas; Bartels, Nils; Steinle, Tobias; Giessen, HaraldItem Open Access Tailored optical functionality by combining electron‐beam and focused gold‐ion beam lithography for solid and inverse coupled plasmonic nanostructures(2020) Hentschel, Mario; Karst, Julian; Giessen, HaraldPlasmonics is a field uniquely driven by advances in micro‐ and nanofabrication. Many design ideas pose significant challenges in their experimental realization and test the limits of modern fabrication techniques. Here, the combination of electron‐beam and gold ion‐beam lithography is introduced as an alternative and highly versatile route for the fabrication of complex and high fidelity plasmonic nanostructures. The capability of this strategy is demonstrated on a selection of planar as well as 3D nanostructures. Large area and extremely accurate structures are presented with little to no defects and errors. These structures exhibit exceptional quality in shape fidelity and alignment precision. The combination of the two techniques makes full use of their complementary capabilities for the realization of complex plasmonic structures with superior optical properties and functionalities as well as ultra‐distinct spectral features which will find wide application in plasmonics, nanooptics, metasurfaces, plasmonic sensing, and similar areas.Item Open Access 3D printing of colored micro-optics(2023) Aslani, Valese; Toulouse, Andrea; Schmid, Michael; Giessen, Harald; Haist, Tobias; Herkommer, AloisItem Open Access Towards fiber-coupled plasmonic perfect absorber superconducting nanowire photodetectors for the near- and mid-infrared(2023) Mennle, Sandra; Karl, Philipp; Ubl, Monika; Ruchka, Pavel; Weber, Ksenia; Hentschel, Mario; Flad, Philipp; Giessen, HaraldItem Open Access Stitching-free 3D printing of millimeter-sized highly transparent spherical and aspherical optical components(2020) Ristok, Simon; Thiele, Simon; Toulouse, Andrea; Herkommer, Alois; Giessen, HaraldItem Open Access 3D direct laser writing of highly absorptive photoresist for miniature optical apertures(2022) Schmid, Michael D.; Toulouse, Andrea; Thiele, Simon; Mangold, Simon; Herkommer, Alois; Giessen, HaraldThe importance of 3D direct laser writing as an enabling technology increased rapidly in recent years. Complex micro-optics and optical devices with various functionalities are now feasible. Different possibilities to increase the optical performance are demonstrated, for example, multi-lens objectives, a combination of different photoresists, or diffractive optical elements. It is still challenging to create fitting apertures for these micro optics. In this work, a novel and simple way to create 3D-printed opaque structures with a highly absorptive photoresist is introduced, which can be used to fabricate microscopic apertures increasing the contrast of 3D-printed micro optics and enabling new optical designs. Both hybrid printing by combining clear and opaque resists, as well as printing transparent optical elements and their surrounding opaque apertures solely from a single black resist by using different printing thicknesses are demonstrated.Item Open Access Compact harmonic cavity optical parametric oscillator for optical parametric amplifier seeding(2020) Nägele, Marco; Steinle, Tobias; Mörz, Florian; Linnenbank, Heiko; Steinmann, Andy; Giessen, HaraldWe present a broadly tunable highly efficient frequency conversion scheme, based on a low-threshold harmonic cavity optical parametric oscillator (OPO) followed by an idler-seeded power amplifier. By choosing the cavity length of the OPO equal to the 10th harmonic of its 41 MHz Yb:KGW solid-state pump laser, a very compact optical setup is achieved. A singly-resonant cavity without output coupler results in a low oscillation threshold of only 28-100 mW in the entire signal tuning range of 1.37-1.8 µm. The 2.4-4.15 µm idler radiation is coupled out at the 41 MHz pump frequency and employed to seed a post amplifier with nearly Watt-level output power. In addition, the seeder plus power amplifier concept results in clean signal and idler pulses at the fundamental repetition rate of 41 MHz with a time-bandwidth product below 0.4 and a relative intensity noise 10 dB lower compared to the solid-state pump laser.