@article{VillasmuntaHeiseBreiteretal.2026, author = {Villasmunta, Francesco and Heise, Patrick and Breiter, Manuela and Schrader, Sigurd and Schenk, Harald and Regehly, Martin and Mai, Andreas}, title = {Monolithically Integrated Optical Through-Silicon Waveguides for 3D Chip-to-Chip Photonic Interconnects}, series = {IEEE Journal of Selected Topics in Quantum Electronics}, volume = {32}, journal = {IEEE Journal of Selected Topics in Quantum Electronics}, number = {2}, publisher = {IEEE}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-20828}, year = {2026}, abstract = {The scaling limitations of electrical interconnects are driving the demand for efficient optical chip-to-chip links. We report the first monolithic integration of air-clad optical through-silicon waveguides in silicon, fabricated via Bosch and cryogenic deep reactive-ion etching. Rib, single-bridge, and double-bridge designs with 50 μm cores and up to 150 μm propagation lengths have been evaluated. Cryogenic-etched rib waveguides achieve the highest median transmission (66\%, -1.80 dB), compared to Bosch-etched ribs (62\%, -2.08 dB). Across all geometries, 3 dB alignment windows range from 9.3 μm to 49.2 μm, with Bosch-etched double-bridge waveguides providing the broadest tolerance. We show that geometric fidelity outweighs sidewall roughness for transmission and alignment in these large-core, multimode optical through-silicon waveguides. This technology provides a scalable, complementary metal-oxide semiconductor-compatible pathway toward 3D photonic interconnects.}, language = {en} } @article{SteglichMaiVillringeretal.2021, author = {Steglich, Patrick and Mai, Christian and Villringer, Claus and Dietzel, Birgit and Bondarenko, Siegfried and Ksianzou, Viachaslau and Villasmunta, Francesco and Zesch, Christoph and Pulwer, Silvio and Burger, Martin and Bauer, Joachim and Heinrich, Friedhelm and Schrader, Sigurd and Vitale, Francesco and De Matteis, Fabio and Prosposito, Paolo and Casalboni, Mauro and Mai, Andreas}, title = {Silicon-organic hybrid photonics: an overview of recent advances, electro-optical effects and CMOS integration concepts}, series = {Journal of Physics: Photonics}, volume = {3}, journal = {Journal of Physics: Photonics}, number = {2}, issn = {2515-7647}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13882}, year = {2021}, abstract = {In recent decades, much research effort has been invested in the development of photonic integrated circuits, and silicon-on-insulator technology has been established as a reliable platform for highly scalable silicon-based electro-optical modulators. However, the performance of such devices is restricted by the inherent material properties of silicon. An approach to overcoming these deficiencies is to integrate organic materials with exceptionally high optical nonlinearities into a silicon-on-insulator photonic platform. Silicon-organic hybrid photonics has been shown to overcome the drawbacks of silicon-based modulators in terms of operating speed, bandwidth, and energy consumption. This work reviews recent advances in silicon-organic hybrid photonics and covers the latest improvements to single components and device concepts. Special emphasis is given to the in-device performance of novel electro-optical polymers and the use of different electro-optical effects, such as the linear and quadratic electro-optical effect, as well as the electric-field-induced linear electro-optical effect. Finally, the inherent challenges of implementing non-linear optical polymers on a silicon photonic platform are discussed and a perspective for future directions is given.}, language = {en} } @article{RegehlyHecht2025, author = {Regehly, Martin and Hecht, Stefan}, title = {Split-Aperture Xolography - Linear Volumetric Photoactivation with Short Axial Dimension and Low out of Focus Excitation}, series = {Advanced Science}, volume = {12}, journal = {Advanced Science}, number = {31}, publisher = {Wiley}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-20749}, year = {2025}, abstract = {Spatially confined photo-excitation with the lowest possible activation of the remaining volume is of central importance for high-resolution high-density optical data storage, fluorescence microscopy, 3D-lithography, and 3D-printing. Two-photon absorption (2PA) enables such applications yet leads to slow processing speed due to the underlying non-linear absorption process. Here, Split-Aperture Xolography (SAX), is introduced which uses stepwise excitation of dual-color responsive molecules to initiate a linear volumetric photo-reaction process that is up to several orders of magnitude more efficient than 2PA. The capabilities of SAX are investigated in a scenario study for focusing systems with high numerical aperture (NA) using a Python implementation of vectorial diffraction theory. The intersecting half-cones generated by the split illuminated entrance aperture of the objective reduce the axial focal spot size of the activation distribution by up to a factor of two compared to 2PA targeting the same electronic transition. A steep average decline of the activation probability with the fifth power away from focus is found for a wide range of directions. This is significantly better in comparison to 2PA and prevents that undesired out-of-focus excitation events sum-up with subsequent irradiations. This approach is expected to be advantageous for volumetric methods at the nanoscale.}, language = {en} } @inproceedings{VillasmuntaSteglichVillringeretal.2024, author = {Villasmunta, Francesco and Steglich, Patrick and Villringer, Claus and Schrader, Sigurd and Schenk, Harald and Mai, Andreas and Regehly, Martin}, title = {Design, fabrication, and characterization of integrated optical through-silicon waveguides for 3D photonic interconnections}, series = {Optical Interconnects XXIV}, volume = {12892}, booktitle = {Optical Interconnects XXIV}, editor = {Chen, Ray T. and Schr{\"o}der, Henning}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-19759}, year = {2024}, abstract = {In the context of an ever-growing volume of data generated by established and emerging technologies, such as 5G, the Internet of Things, artificial intelligence, machine learning, blockchain, and virtual reality, faster communication speed is demanded by data centers and high-performance computing. Transceiver requirements surged from 100 to 400 Gb/s and beyond. In this scenario, photonics aims to enable Tb/s optical communication at energies below 1 pJ/bit. Targeting higher communication rates while maintaining a low power budget can significantly benefit from 3D photonic chip architectures. This paper presents the simulation-based design, fabrication, and characterization of a monolithically integrated optical through-silicon waveguide that facilitates the connection between different surfaces of a silicon chip. Deep reactive ion etching was employed in both the Bosch and Cryogenic variants to evaluate the effect of sidewall roughness on propagation losses. The mechanical stability of the waveguide was ensured by interrupting the annular trench with a bridging structure. The high-refractive-index contrast to air provides tight light confinement for a core size of up to 50 μm and multimode operation at 1550 nm. The morphology was characterized using scanning electron microscopy (SEM), and optical transmission characterization was performed using relative power loss measurements. A tunable laser source was buttcoupled to a waveguide to analyze light transmission efficiency. Preliminary measurements using single-mode fiber show that the transmitted values exceeded 99\% for all structures.}, language = {en} } @article{BauerHeinrichVillasmuntaetal.2025, author = {Bauer, Joachim and Heinrich, Friedhelm and Villasmunta, Francesco and Villringer, Claus and Reck, Johanna and Peters, Sven and Treffer, Alexander and Kuhnt, Christian and Marschmeyer, Steffen and Fursenko, Oksana and Stolarek, David and Mai, Andreas and Regehly, Martin}, title = {Reflectometric method for measuring residual oxides in through-silicon vias for 3D chip integration}, series = {Optics Express}, volume = {33}, journal = {Optics Express}, number = {15}, publisher = {Optica}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-20633}, pages = {32175 -- 32189}, year = {2025}, abstract = {A significant aspect of fabricating 3D chip architectures is ensuring proper contact between the different layers of the chip, which often requires removing the underside of isolation layers before filling vias with conductive material. Currently, scanning electron microscopy is the established method for investigating such structures. In this paper, we propose a rapid, non-destructive optical analysis technique for the simultaneous measurement of through-silicon vias (TSV) depths, silicon wafer thickness, and residual oxide thickness. The proposed method utilizes Fourier peak shift analysis (FPSA) of reflectance measurements in the near-infrared (1200 nm—2200 nm) spectral regions. The application of FPSA to representative samples taken from a commercial TSV integration process for MEMS and CMOS fabrication demonstrated good agreement with reference scanning electron microscopy measurements, confirming the feasibility of the method for in-line and in-situ metrology. The results indicate that FPSA has great potential for real-time process monitoring and control during 3D chip manufacturing.}, language = {en} } @article{BauerFursenkoMarschmeyeretal.2019, author = {Bauer, Joachim and Fursenko, Oksana and Marschmeyer, Steffen and Heinrich, Friedhelm and Villasmunta, Francesco and Villringer, Claus and Zesch, Christoph and Schrader, Sigurd}, title = {Spectroscopic reflectometry for characterization of Through Silicon Via profile of Bosch etching process}, series = {Journal of Vacuum Science \& Technology B}, volume = {37}, journal = {Journal of Vacuum Science \& Technology B}, number = {6}, publisher = {American Vacuum Society (AVS)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-16093}, year = {2019}, abstract = {Through Silicon Via (TSV) technology is a key in 3D integration of circuits by the creation of interconnects using vias, which go through the full silicon wafer. Typically, a highly-selective Bosch Si etch process is used. It is characterized by a high etch rate at a high aspect ratio, whereby scallops on the sidewalls are generated. In this work, square via arrays with dimensions from 3 to 50 μm and up to 300 μm depth were fabricated and analyzed by spectroscopic reflectometry. The reflectometric data are compared to simulations by a novel theoretical approach. In order to simulate the reflectance spectra of TSV arrays, a combination of 2D and 3D rigorous coupled wave analysis was applied. Besides the via depth, the sidewall angle and the corner radius of the bottom profile were considered in the model. The general requirements on spectral resolution in TSV metrology are discussed.}, language = {en} } @misc{vandeSandReiffStephan2021, author = {van de Sand, Ron and Reiff-Stephan, J{\"o}rg}, title = {FrostByte Dataset}, doi = {10.15771/1894}, year = {2021}, abstract = {It is with great pleasure that we announce the release of the "Frost Byte" dataset. The dataset was collected during research on fault detection and diagnosis (FDD) approaches and their transferability to heterogeneous systems of industrial refrigeration systems at the Technical University of Applied Sciences Wildau. The data collection took place between 2018 and 2019 and is intended to supplement the ASHRAE 1043-RP dataset (Comstock \& Braun, 1999), which has been the only publicly available data source in this area to date. For comparison purposes, the method of data collection was chosen similarly, whereby this dataset collection was carried out using a ~ 100 kW refrigeration capacity ammonia system with plate heat exchangers. The dataset contains steady-state data equally sampled from five classes: 1. Normal (fault-free operating condition) 2. Reduced Condenser Water Flow 3. Reduced Evaporator Water Flow 4. Non-Condensable Gases 5. Refrigeration Leak Each class was investigated under changing operational conditions and varying fault severity levels (SL).}, language = {en} } @misc{HartmannTataiKaiseretal.2019, author = {Hartmann, Lutz and Tatai, Tiberiu-Mihai and Kaiser, Mario and Dreyer, Christian}, title = {Erw{\"a}rmung von Materialien und Werkstoffen durch Anwendung von Mikrowellentechnologien}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_6}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10812}, pages = {39 -- 48}, year = {2019}, abstract = {Die Erw{\"a}rmung unterschiedlicher Materialien im ­Kontext verschiedener Anwendungen kann anhand der Bestrahlung mit Mikrowellen in geeignet konstruierten {\"O}fen erfolgen. Der vorliegende Beitrag beginnt mit einer Vorstellung der mikroskopischen Mechanismen der Erw{\"a}rmung von Materie mittels Mikrowellen sowie einem Abriss ihrer theoretischen Beschreibung. Im Folgenden werden die breitbandige dielektrische Spektroskopie und die Simulation elektromagnetischer Felder als Hilfsmittel eingef{\"u}hrt, die Effizienz des mikrowellenbasierten Heizens f{\"u}r bestimmte Materialien vorab einsch{\"a}tzen zu k{\"o}nnen. Nach der Vorstellung zweier unterschiedlicher Mikrowellenanlagen, namentlich eines Kammer- und eines Durchlaufmikrowellenofens, wird die thermische Behandlung unterschiedlicher Materialien mittels Mikrowellen an drei Beispielen illustriert.}, language = {de} } @misc{HotesSchwahnFabienke2019, author = {Hotes, Andreas G. and Schwahn, Klaus-J{\"u}rgen and Fabienke, Henrike}, title = {Betrachtung von neuartigen Antriebs- und Kraftstoffkonzepten mit dem Ziel der Konzeption ­einer Hybridtankstelle f{\"u}r den Flugplatz Sch{\"o}nhagen f{\"u}r die Versorgung von Luftfahrzeugen mit nachhaltigen Kraftstoffen}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_7}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-11939}, pages = {49 -- 55}, year = {2019}, abstract = {Dieser wissenschaftliche Beitrag befasst sich zun{\"a}chst mit der Betrachtung von neuartigen und nachhaltigen Antriebs- und Kraftstoffkonzepten f{\"u}r den Einsatz in der Luftfahrt, die zum Erreichen der hochgesteckten Klimaschutzziele auf nationaler, europ{\"a}ischer und internationaler Ebene beitragen sollen. Um die Energieversorgung dieser Luftfahrzeuge gew{\"a}hrleisten zu k{\"o}nnen, wurde ein Tankstellensystem beispielhaft f{\"u}r den Flugplatz Sch{\"o}nhagen konzipiert, welches Strom, Wasserstoff und Power-to-Liquid-Kraftstoff f{\"u}r Elektro-, Wasserstoff- und Luftfahrzeuge mit konventionellem Verbrennungsmotor sowie f{\"u}r Hybridflugzeuge zur Verf{\"u}gung stellen soll. Ziel dieses Konzeptes ist die komplette Eigenproduktion der Kraftstoffe auf dem Flugplatz. Hierzu wurden rechtliche, wirtschaftliche und vor allem technische Voraussetzungen untersucht und ausgewertet sowie Berechnungen bez{\"u}glich der ben{\"o}tigten Kraftstoff- und Stromkapazit{\"a}ten durchgef{\"u}hrt.}, language = {de} } @misc{GerhardLetienCressentetal.2019, author = {Gerhard, Christoph and Letien, Emilie and Cressent, Thomas and Hofmann, Mandy}, title = {Impact of the plasma power on plasma-induced increase in absorption of fused silica}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_5}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10802}, pages = {33 -- 37}, year = {2019}, abstract = {In the last decades, laser machining of fused silica has gained in importance where the main challenge is to overcome the high transmission of this medium in order to achieve surface absorption. One approach is plasma treatment using hydrogenous process gases. In doing so, a near-surface glass layer is chemically modified by a removal of oxygen and an implantation of hydrogen, resulting in the formation of optically active defects and an increase in absorption. Against this background, the impact of the plasma power on plasma-induced increase in absorption of fused silica was investigated in the present work. Here, the highest efficiency of the plasma treatment process was found at the lowest applied plasma power whereas for higher plasma powers, a notably lower increase in absorption was observed. This effect is attributed to the decomposition of plasma species required for initiating the formation of optically active defects within the glass. Such decomposition increases with rising power due to the corresponding increase in electric field strength within the plasma. This finding is of substantial interest for an extensive understanding of plasma-glass interactions.}, language = {en} } @misc{HandrichVandenhouten2019, author = {Handrich, Jan and Vandenhouten, Ralf}, title = {Erweiterung eines landmarkenbasierten Innenraumortungsverfahrens f{\"u}r Mobilger{\"a}te mit ARCore}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_4}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10790}, pages = {27 -- 32}, year = {2019}, abstract = {Die Lokalisierung in Innenr{\"a}umen, die sich nicht auf Satellitennavigation wie GPS verlassen kann, ist nach wie vor eine Herausforderung. Viele Methoden zur Lokalisierung in Innenr{\"a}umen beruhen auf Funksignalen oder anderen Sendern (z.B. Infrarot), die eine kostenintensive Infrastruktur erfordern, die in einem Geb{\"a}ude installiert werden muss. Außerdem sind diese Techniken ungenau, wenn Reflexionen der Signale in einem Geb{\"a}ude auftreten. Die Forschungsgruppe Telematik der TH Wildau hat f{\"u}r diese Problemstellung ein optisches Verfahren zur Innenraumlokalisierung entwickelt, das die Kamera eines mobilen Ger{\"a}ts verwendet. Dieser Ansatz erfordert nur die Verf{\"u}gbarkeit von mehreren identifizierbaren Landmarken, die kosteng{\"u}nstig in einem Geb{\"a}ude installiert werden k{\"o}nnen. In diesem Beitrag soll eine M{\"o}glichkeit vorgestellt werden, dieses landmarkenbasierte Verfahren mit der Augmented Reality-Bibliothek ARCore von Google zu erweitern, um eine kontinuierliche Positionsermittlung zu erm{\"o}glichen, auch wenn vor{\"u}bergehend keine Landmarken durch die Ger{\"a}tekamera erfasst ­werden k{\"o}nnen.}, language = {de} }