@article{SteglichVillringerDietzeletal.2019, author = {Steglich, Patrick and Villringer, Claus and Dietzel, Birgit and Mai, Christian and Schrader, Sigurd and Casalboni, Mauro and Mai, Andreas}, title = {On-Chip Dispersion Measurement of the Quadratic Electro-Optic Effect in Nonlinear Optical Polymers Using a Photonic Integrated Circuit Technology}, series = {IEEE Photonics Journal}, volume = {11}, journal = {IEEE Photonics Journal}, number = {3}, issn = {1943-0655}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-12307}, year = {2019}, abstract = {A novel method to determine the dispersion of the quadratic electro-optic effect in nonlinear optical materials by using a silicon-on-insulator microring resonator is presented. The microring consists of a silicon slot waveguide enabling large dc electric field strength at low applied voltages. The dispersion of third-order hyperpolarizability of a linear conjugated dye is approximated by using a two-level model for the off-resonant spectral region. As an example, the dispersion of the resonance wavelength of the resonator filled with a dye doped polymer was measured in dependence of the applied dc voltage. The polymer was poly (methylmethacrylate) doped with 5 wt\% disperse red 1 (DR1), and the measurements have been carried out at the telecommunication wavelength band around 1550 nm (optical C-band). The described measurements represent a new technique to determine the dispersion of the third-order susceptibility and molecular hyperpolarizability of the material filled into the slot of the ring-resonator.}, language = {en} } @inproceedings{BauerHeinrichFursenkoetal.2017, author = {Bauer, Joachim and Heinrich, Friedhelm and Fursenko, Oksana and Marschmeyer, Steffen and Bluemich, Adrian and Pulwer, Silvio and Steglich, Patrick and Villringer, Claus and Mai, Andreas and Schrader, Sigurd}, title = {Very high aspect ratio through silicon via reflectometry}, series = {Proceedings of SPIE}, booktitle = {Proceedings of SPIE}, issn = {1996-756X}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13758}, year = {2017}, abstract = {Through Silicon Via (TSV) technology is a key feature of new 3D integration of circuits by creation of interconnections using vias, which go through the silicon wafer. Typically, the highly-selective Bosch Si etch process, characterized by a high etch rate and high aspect ratio and forming of scallops on the sidewalls is used. As presented in this paper, we have developed an experimental setup and a respective evaluation algorithm for the control and monitoring of very high aspect ratio TSV profiles by spectroscopic reflectometry. For this purpose square via arrays with lateral dimension from 3 to 10 μm were fabricated by a Bosch etch process and analyzed by our setup. By exploiting interference and diffraction effects of waves reflected from the top and bottom surfaces as well as from the side walls of the TSV patterns, the measurements provided etch depths, CD values and scallop periods. The results were compared with data obtained by a commercial wafer metrology tool. Aspect ratios of up to 35:1 were safely evaluable by our setup.}, language = {en} } @inproceedings{BadoniBonaiutoCasalbonietal.2020, author = {Badoni, Davide and Bonaiuto, Vincenzo and Casalboni, Mauro and De Matteis, Fabio and Di Giuseppe, Giovanni and Frontini, Luca and Gunnella, Roberto and Liberali, Valentino and Mai, Andreas and Paoluzzi, Giovanni and Prosposito, Paolo and Salamon, Andrea and Salina, Gaetano and Sargeni, Fausto and Schrader, Sigurd and Stabile, Alberto and Steglich, Patrick}, title = {Characterization and Tests of Different Mach-Zehnder Silicon Photonic Modulator Configurations}, series = {Photonics and Photoactive Materials}, booktitle = {Photonics and Photoactive Materials}, editor = {Prosposito, Paolo}, publisher = {Materials Research Forum LLC}, address = {Millersville, PA}, isbn = {978-1-64490-071-0}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13731}, pages = {1 -- 5}, year = {2020}, abstract = {We designed and produced an integrated silicon photonic circuit, in a single chip with IHP SG25H4_EPIC 0.25 µm technology. A Mach-Zehnder interferometer with an alternative shape for better integration, together with a standard-shape Mach-Zehnder interferometer have been realized. In this work, preliminary results of comparative performance measurements between the two Mach-Zehnder interferometer are shown.}, language = {en} } @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} } @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{SteglichMaiVillringeretal.2018, author = {Steglich, Patrick and Mai, Christian and Villringer, Claus and Pulwer, Silvio and Casalboni, Mauro and Schrader, Sigurd and Mai, Andreas}, title = {Quadratic electro-optic effect in silicon-organic hybrid slot-waveguides}, series = {Optics Letters}, volume = {43}, journal = {Optics Letters}, number = {15}, issn = {1539-4794}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-12148}, year = {2018}, abstract = {This Letter reports on the quadratic electro-optic effect of polymers, observed in a silicon slot-waveguide at low voltages. We demonstrate that in narrow slots, the electro-optic response with respect to refractive index change is strong enough for on-chip wavelength tuning and intensity modulation using voltages as low as 1 V. A silicon slot-waveguide embedded by a nonlinear optical polymer, consisting of the dye Disperse Red 1 in poly(methyl methacrylate), serves as the phase shifter in a racetrack ring resonator. As deduced from the experimental data, the third-order susceptibility of the utilized electro-optic polymer is about 2·10-19 m2/V2. The demonstrated low-voltage operation and inherently thermal stability show the potential for silicon-organic hybrid devices using the quadratic electro-optic effect.}, language = {en} }