TY - JOUR A1 - Steglich, Patrick A1 - Mai, Christian A1 - Villringer, Claus A1 - Mai, Andreas T1 - Direct observation and simultaneous use of linear and quadratic electro-optical effects JF - Journal of Physics D: Applied Physics N2 - We report on the direct observation and simultaneous use of the linear and quadratic electro-optical effect and propose a method by which higher-order susceptibilities of electro-optical materials can be determined. The evaluation is based on the separation of the second- and third-order susceptibilities and the experimental technique uses a slot waveguide ring resonator fabricated in integrated photonic circuit technology, which is embedded by a guest-host polymer system consisting of the azobenzene dye Disperse Red 1 in a poly(methyl methacrylate) matrix as an active electro-optical material. The contribution of both effects on the electro-optical response under the influence of static and time-varying electrical fields is investigated. We show that the quadratic electro-optical effect has a significant influence on the overall electro-optical response even with acentric molecular orientated molecules. Our findings have important implications for developing electro-optical devices based on polymer-filled slot waveguides and give rise to advanced photonic circuits. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13032 SN - 1361-6463 VL - 53 IS - 12 ER - TY - JOUR A1 - Steglich, Patrick A1 - Villringer, Claus A1 - Dietzel, Birgit A1 - Mai, Christian A1 - Schrader, Sigurd A1 - Casalboni, Mauro A1 - Mai, Andreas T1 - On-Chip Dispersion Measurement of the Quadratic Electro-Optic Effect in Nonlinear Optical Polymers Using a Photonic Integrated Circuit Technology JF - IEEE Photonics Journal N2 - 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. KW - electro-optical device KW - nonlinear optics KW - integrated optics KW - integrated optics material KW - optical material KW - integrated optics device KW - polymer active device Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-12307 SN - 1943-0655 VL - 11 IS - 3 ER - TY - JOUR A1 - Mai, Andreas A1 - Mai, Christian A1 - Steglich, Patrick T1 - From Lab-on-chip to Lab-in-App: Challenges towards silicon photonic biosensors product developments JF - Results in Optics N2 - This work presents and evaluates different approaches of integrated optical sensors based on photonic integrated circuit (PIC) technologies for refractive index sensing. Bottlenecks in the fabrication flow towards an applicable system are discussed that hinder a cost-effective mass-production for disposable sensor chips. As sensor device, a waveguide coupled micro-ring based approach is chosen which is manufactured in an 8” wafer level process. We will show that the co-integration with a reproducible, scalable and low-cost microfluidic interface is the main challenge which needs to be overcome for future application of silicon technology based PIC sensor chips. KW - silicon photonic sensor KW - integrated optical sensor KW - photonic integrated circuit KW - optical ring resonator KW - photonic biosensor KW - refractive index sensing KW - interchangeable sensor chip Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16687 SN - 2666-9501 VL - 9 PB - Elsevier ER - TY - JOUR A1 - Anand, Ketan A1 - Steglich, Patrick A1 - Kreissl, Jochen A1 - Chavarin, Carlos Alvarado A1 - Spirito, Davide A1 - Franck, Max A1 - Lecci, Giulia A1 - Costina, Ioan A1 - Herfurth, Norbert A1 - Katzer, Jens A1 - Mai, Christian A1 - Becker, Annette A1 - Reithmaier, Johann Peter A1 - Zimmermann, Lars A1 - Mai, Andreas T1 - Adhesive-free bonding for hetero-integration of InP based coupons micro-transfer printed on SiO2 into Complementary Metal-Oxide-Semiconductor backend for Si photonics application on 8” wafer platform JF - Thin Solid Films N2 - Micro-Transfer printing (µTP) is a promising technique for hetero-integration of III-V materials into Si-based photonic platforms. To enhance the print yield by increasing the adhesion between the III-V material and Si or SiO2 surface, an adhesion promoter like Benzocyclobutene is typically used as interlayer. In this work, we demonstrate µTP of InP based coupons on SiO2 interlayer without any adhesive interlayer and investigate the mechanism of adhesive free bonding. Source coupons are InP-based coupon stacks on a sacrificial layer that is removed by a chemical wet etch with FeCl3. For the target we fabricated amorphous-Si waveguides on 8” wafer encapsulated by a High Density Plasma SiO2 which was planarized by a chemical mechanical polishing procedure. We used O2 plasma to activate both source and target to increase adhesion between coupon and substrate. To get a better understanding of the bonding mechanism we applied several surface characterization methods. Root mean square roughness of InP and SiO2 was measured by atomic force microscopy before and after plasma activation. The step height of the micro-transfer printed source coupon on the target wafer is estimated by optical step profiler. We used Raman peak position mappings of InP to analyze possible strain and contact angle measurements on SiO2, before and after plasma activation to observe a change in the hydrophilicity of the surface. X-ray Photoelectron Spectroscopy analysis was used to characterize the surface energy states of P2p, In3d, O1s for InP source and Si2p, O1s for SiO2 target. Our results demonstrate direct bonding of InP coupons by means of µTP without the need of a strain-compensation layer. In this way, a promising route towards Complementary Metal-Oxide-Semiconductor compatible use of µTP for the hetero-integration of InP is provided. KW - hetero-integration KW - micro-transfer printing KW - indium Phosphide KW - silicon oxide KW - sacrificial layer KW - oxygen plasma activation Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-19240 SN - 0040-6090 IS - 140399 PB - Elsevier ER - TY - INPR A1 - Steglich, Patrick A1 - Rabus, Dominik G. A1 - Sada, Cinzia A1 - Paul, Martin A1 - Weller, Michael G. A1 - Mai, Christian A1 - Mai, Andreas T1 - Silicon Photonic Micro-Ring Resonators for Chemical and Biological Sensing: A Tutorial T2 - TechRxiv N2 - Silicon photonic micro-ring resonators (MRR) developed on the silicon-on-insulator (SOI) platform, owing to their high sensitivity and small footprint, show great potential for many chemical and biological sensing applications such as label-free detection in environmental monitoring, biomedical engineering, and food analysis. In this tutorial, we provide the theoretical background and give design guidelines for SOI-based MRR as well as examples of surface functionalization procedures for label-free detection of molecules. After introducing the advantages and perspectives of MRR, fundamentals of MRR are described in detail, followed by an introduction to the fabrication methods, which are based on a complementary metal-oxide semiconductor (CMOS) technology. Optimization of MRR for chemical and biological sensing is provided, with special emphasis on the optimization of waveguide geometry. At this point, the difference between chemical bulk sensing and label-free surface sensing is explained, and definitions like waveguide sensitivity, ring sensitivity, overall sensitivity as well as the limit of detection (LoD) of MRR are introduced. Further, we show and explain chemical bulk sensing of sodium chloride (NaCl) in water and provide a recipe for label-free surface sensing. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16840 ER - TY - JOUR A1 - Steglich, Patrick A1 - Bondarenko, Siegfried A1 - Mai, Christian A1 - Paul, Martin A1 - Weller, Michael G. A1 - Mai, Andreas T1 - CMOS-Compatible Silicon Photonic Sensor for Refractive Index Sensing Using Local Back-Side Release JF - IEEE Photonics Technology Letters N2 - Silicon photonic sensors are promising candidates for lab-on-a-chip solutions with versatile applications and scalable production prospects using complementary metal-oxide semiconductor (CMOS) fabrication methods. However, the widespread use has been hindered because the sensing area adjoins optical and electrical components making packaging and sensor handling challenging. In this work, a local back-side release of the photonic sensor is employed, enabling a separation of the sensing area from the rest of the chip. This approach allows preserving the compatibility of photonic integrated circuits in the front-end of line and metal interconnects in the back-end of line. The sensor is based on a micro-ring resonator and is fabricated on wafer-level using a CMOS technology. We revealed a ring resonator sensitivity for homogeneous sensing of 106 nm/RIU. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13649 SN - 1941-0174 VL - 32 IS - 19 SP - 1241 EP - 1244 ER - TY - CHAP A1 - Steglich, Patrick A1 - Paul, Martin A1 - Mai, Christian A1 - Böhme, Andrea A1 - Bondarenko, Siegfried A1 - Weller, Michael G. A1 - Mai, Andreas T1 - A monolithically integrated micro fluidic channel in a silicon-based photonic-integrated-circuit technology for biochemical sensing T2 - Proc. SPIE 11772, Optical Sensors 2021 N2 - In this work, a cost-effective optofluidic system is propossed and preliminary experimental results are presented. A microfluidic channel monolithically integrated into a photonic integrated circuit technology is used in conjunc- tion with a cyclo-olefin copolymer (COC) substrate to provide fluidic in- and output ports. We report on initial experimental results as well as on the simple and cost-effective fabrication of this optofluidic system by means of micro-milling. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13925 ER - TY - CHAP A1 - Fünning, Tabea A1 - Peczek, Anna A1 - Kroh, Aleksandra A1 - Mai, Christian A1 - Paul, Martin A1 - Thomsen, Florian A1 - Tannenberg, Robert A1 - Schumann, Christoph A1 - Weller, Michael G. A1 - Mai, Andreas A1 - Steglich, Patrick ED - Baldini, Francesco ED - Homola, Jiri ED - Lieberman, Robert A. T1 - Optimization of local backside released micro-ring resonators for sensing applications using silicon photonic integrated circuits in a SOI technology T2 - Proceedings of SPIE : Optical Sensors 2025 N2 - Photonic micro-ring resonators (MRR) are widely studied for their high sensitivity across applications like environmental monitoring, healthcare, and chemical analysis. Their evanescent field sensing requires partially unembedded waveguides compatible with CMOS processing. Our approach uses local backside etching with an additional buried oxide (BOX) etch to release waveguides while preserving the back-end of line (BEOL) structure, enabling spatial separation of the sensing area and electronics. The BOX etch critically affects sensor performance, as waveguide surface roughness can alter MRR properties and coupling. We analyzed MRR design variations, comparing wet and dry etching techniques for their effects on optical performance across rib and strip waveguides in quasi-TE and quasi-TM modes. Wafer-level measurements show that backside-released MRR achieve high extinction ratios with slightly reduced quality factors, advancing high-sensitivity photonic sensors. KW - photonic sensor KW - micro-ring resonator (MRR) KW - silicon-on-insulator (SOI) KW - local backside etching (LBE) Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-20449 VL - 13527 PB - SPIE ER - TY - JOUR A1 - Steglich, Patrick A1 - Mai, Christian A1 - Villringer, Claus A1 - Dietzel, Birgit A1 - Bondarenko, Siegfried A1 - Ksianzou, Viachaslau A1 - Villasmunta, Francesco A1 - Zesch, Christoph A1 - Pulwer, Silvio A1 - Burger, Martin A1 - Bauer, Joachim A1 - Heinrich, Friedhelm A1 - Schrader, Sigurd A1 - Vitale, Francesco A1 - De Matteis, Fabio A1 - Prosposito, Paolo A1 - Casalboni, Mauro A1 - Mai, Andreas T1 - Silicon-organic hybrid photonics: an overview of recent advances, electro-optical effects and CMOS integration concepts JF - Journal of Physics: Photonics N2 - 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. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13882 SN - 2515-7647 VL - 3 IS - 2 ER - TY - JOUR A1 - Steglich, Patrick A1 - Mai, Christian A1 - Villringer, Claus A1 - Pulwer, Silvio A1 - Casalboni, Mauro A1 - Schrader, Sigurd A1 - Mai, Andreas T1 - Quadratic electro-optic effect in silicon-organic hybrid slot-waveguides JF - Optics Letters N2 - 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. Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-12148 SN - 1539-4794 VL - 43 IS - 15 ER - TY - JOUR A1 - Anand, Ketan A1 - Schubert, Markus Andreas A1 - Corley-Wiciak, Agnieszka Anna A1 - Spirito, Davide A1 - Corley-Wiciak, Cedric A1 - Klesse, Wolfgang M. A1 - Mai, Andreas A1 - Tillack, Bernd A1 - Yamamoto, Yuji T1 - Lateral Selective SiGe Growth for Local Dislocation-Free SiGe-on-Insulator Virtual Substrate Fabrication JF - ECS Journal of Solid State Science and Technology N2 - Dislocation free local SiGe-on-insulator (SGOI) virtual substrate is fabricated using lateral selective SiGe growth by reduced pressure chemical vapor deposition. The lateral selective SiGe growth is performed around a ∼1.25 μm square Si (001) pillar in a cavity formed by HCl vapor phase etching of Si at 850 °C from side of SiO2/Si mesa structure on buried oxide. Smooth root mean square roughness of SiGe surface of 0.14 nm, which is determined by interface roughness between the sacrificially etched Si and the SiO2 cap, is obtained. Uniform Ge content of ∼40% in the laterally grown SiGe is observed. In the Si pillar, tensile strain of ∼0.65% is found which could be due to thermal expansion difference between SiO2 and Si. In the SiGe, tensile strain of ∼1.4% along 〈010〉 direction, which is higher compared to that along 〈110〉 direction, is observed. The tensile strain is induced from both [110] and [−110] directions. Threading dislocations in the SiGe are located only ∼400 nm from Si pillar and stacking faults are running towards 〈110〉 directions, resulting in the formation of a wide dislocation-free area in SiGe along 〈010〉 due to horizontal aspect ratio trapping. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-17013 VL - 12 PB - Electrochemical Society (ECS); IOP ER - TY - JOUR A1 - Kalishettyhalli Mahadevaiah, Mamathamba A1 - Pérez, Eduardo A1 - Lisker, Marco A1 - Schubert, Markus Andreas A1 - Perez-Bosch Quesada, Emilio A1 - Wenger, Christian A1 - Mai, Andreas T1 - Modulating the Filamentary-Based Resistive Switching Properties of HfO₂ Memristive Devices by Adding Al₂O₃ Layers JF - Electronics N2 - The resistive switching properties of HfO₂ based 1T-1R memristive devices are electrically modified by adding ultra-thin layers of Al₂O₃ into the memristive device. Three different types of memristive stacks are fabricated in the 130 nm CMOS technology of IHP. The switching properties of the memristive devices are discussed with respect to forming voltages, low resistance state and high resistance state characteristics and their variabilities. The experimental I–V characteristics of set and reset operations are evaluated by using the quantum point contact model. The properties of the conduction filament in the on and off states of the memristive devices are discussed with respect to the model parameters obtained from the QPC fit. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16172 SN - 2079-9292 VL - 11 IS - 10 CY - MDPI ER - TY - JOUR A1 - Steglich, Patrick A1 - Hülsemann, Marcel A1 - Dietzel, Birgit A1 - Mai, Andreas T1 - Optical Biosensors Based on Silicon-On-Insulator Ring Resonators: A Review JF - Molecules N2 - Recent developments in optical biosensors based on integrated photonic devices are reviewed with a special emphasis on silicon-on-insulator ring resonators. The review is mainly devoted to the following aspects: (1) Principles of sensing mechanism, (2) sensor design, (3) biofunctionalization procedures for specific molecule detection and (4) system integration and measurement set-ups. The inherent challenges of implementing photonics-based biosensors to meet specific requirements of applications in medicine, food analysis, and environmental monitoring are discussed. KW - biosensor KW - biophotonics KW - integrated optical sensor KW - aptamer KW - biomaterial KW - optical sensor KW - silicon photonics KW - ring resonator KW - lab-on-a-chip Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-10822 SN - 1420-3049 VL - 24 IS - 3 ER - TY - JOUR A1 - Steglich, Patrick A1 - Lecci, Giulia A1 - Mai, Andreas T1 - Surface Plasmon Resonance (SPR) Spectroscopy and Photonic Integrated Circuit (PIC) Biosensors: A Comparative Review JF - Sensors N2 - Label-free direct-optical biosensors such as surface-plasmon resonance (SPR) spectroscopy has become a gold standard in biochemical analytics in centralized laboratories. Biosensors based on photonic integrated circuits (PIC) are based on the same physical sensing mechanism: evanescent field sensing. PIC-based biosensors can play an important role in healthcare, especially for point-of-care diagnostics, if challenges for a transfer from research laboratory to industrial applications can be overcome. Research is at this threshold, which presents a great opportunity for innovative on-site analyses in the health and environmental sectors. A deeper understanding of the innovative PIC technology is possible by comparing it with the well-established SPR spectroscopy. In this work, we shortly introduce both technologies and reveal similarities and differences. Further, we review some latest advances and compare both technologies in terms of surface functionalization and sensor performance. KW - surface plasmon resonance KW - photonic integrated circuit KW - biosensor KW - surface functionalization KW - label-free detection Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16018 SN - 1424-8220 VL - 22 IS - 8 PB - MDPI ER - TY - CHAP A1 - Fursenko, Oksana A1 - Lukosius, Mindaugas A1 - Lupina, G. A1 - Bauer, Joachim A1 - Villringer, Claus A1 - Mai, Andreas T1 - Development of graphene process control by industrial optical spectroscopy setup N2 - The successful integration of graphene into microelectronic devices depends strongly on the availability of fast and nondestructive characterization methods of graphene grown by CVD on large diameter production wafers [1-3] which are in the interest of the semiconductor industry. Here, a high-throughput optical metrology method for measuring the thickness and uniformity of large-area graphene sheets is demonstrated. The method is based on the combination of spectroscopic ellipsometry and normal incidence reflectometry in UV-Vis wavelength range (200-800 nm) with small light spots (~ 30 μm2) realized in wafer optical metrology tool. In the first step graphene layers were transferred on a SiO2/Si substrate in order to determine the optical constants of graphene by the combination of multi-angle ellipsometry and reflectometry. Then these data were used for the development of a process control recipe of CVD graphene on 200 mm Ge(100)/Si(100) wafers. The graphene layer quality was additionally monitored by Raman spectroscopy. Atomic force microscopy measurements were performed for micro topography evaluation. In consequence, a robust recipe for unambiguous thickness monitoring of all components of a multilayer film stack, including graphene, surface residuals or interface layer underneath graphene and surface roughness is developed. Optical monitoring of graphene thickness uniformity over a wafer has shown an excellent long term stability (s=0.004 nm) regardless of the growth of interfacial GeO2 and surface roughness. The sensitivity of the optical identification of graphene during microelectronic processing was evaluated. This optical metrology technique with combined data collection exhibit a fast and highly precise method allowing one an unambiguous detection of graphene after transferring as well as after the CVD deposition process on a Ge(100)/Si(100) wafer. This approach is well suited for industrial applications due to its repeatability and flexibility. KW - graphene KW - spectroscopic ellipsometry KW - optical constant KW - reflectometry KW - optical metrology KW - AFM KW - Raman spectroscopy Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-15319 SP - 250 EP - 259 PB - SPIE ER - TY - JOUR A1 - Fursenko, Oksana A1 - Lukosius, Mindaugas A1 - Bauer, Joachim A1 - Villringer, Claus A1 - Lux, Helge A1 - Bärwolf, Florian A1 - Lisker, Marco A1 - Mai, Andreas T1 - Diagnostic of graphene on Ge(100)/Si(100) in a 200 mm wafer Si technology environment by spectroscopic ellipsometry/reflectometry JF - Journal of Vacuum Science & Technology B N2 - Comprehensive diagnostics is a prerequisite for the application of graphene in semiconductor technologies. Here, the authors present long-term investigations of graphene on 200-mm Ge(100)/Si(100) wafers under clean room environmental conditions. Diagnostic of graphene was performed by a fast and nondestructive metrology method based on the combination of spectroscopic ellipsometry and reflectometry (SE/R), realized within a wafer optical metrology tool. A robust procedure for unambiguous thickness monitoring of a multilayer film stack, including graphene, interface layer GeOx underneath graphene, and surface roughness is developed and applied for process control. The authors found a relationship between the quality of graphene and the growth of GeOx beneath graphene. Enhanced oxidation of Ge beneath graphene was registered as a long-term process. SE/R measurements were validated and complemented using atomic force microscopy, scanning electron microscopy, Raman spectroscopy, and secondary ion mass spectrometry. This comparative study shows a high potential for optical metrology of graphene deposited on Ge/Si structures, due to its great sensitivity, repeatability, and flexibility, realized in a nondestructive way. Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16083 VL - 37 IS - 6 PB - American Vacuum Society (AVS) ER - TY - CHAP A1 - Steglich, Patrick A1 - Mai, Andreas T1 - Analysis of BTO-on-Si-waveguides for energy-efficient electro-optical modulators T2 - Proc. SPIE 11775, Integrated Optics: Design, Devices, Systems and Applications VI N2 - In this work, we analyze a horizontal slot waveguide configuration, which evaluates the potential for an integration of barium titanate (BTO) based modulators into a photonic integrated circuit (PIC) technology based on siliconon- insulator (SOI) wafer. The waveguide configuration consists of a doped crystal silicon layer, a Ba0:7Sr0:3TiO3 (BST) template layer, a barium titanate (BTO) layer and a doped poly-silicon layer on top. In contrast to current approaches, we analyze the performance of this waveguide-structure by using a vertical electrode configuration that is formed by the doped silicon layer. In this way, the electric field strength is dramatically increased compared to current horizontal electrode configuration. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13934 ER - TY - JOUR A1 - Bondarenko, Siegfried A1 - Hülsemann, Marcel A1 - Mai, Andreas A1 - Steglich, Patrick T1 - Fiber-to-chip light coupling using a graded-index lensed fiber collimator JF - Optical Engineering N2 - Fiber-to-chip light coupling using a graded-index (GRIN) fiber collimator is investigated. Our experiments with grating couplers and strip waveguides fabricated in a photonic integrated circuit technology reveal that the peak coupling efficiency of a GRIN fiber collimator is 7.8 dB lower than that of a single-mode fiber. However, the 3-dB alignment tolerance is improved by a factor of about 5.7 giving rise to pluggable sensor solutions. This work opens a path toward a cost-effective and portable sensor platform based on pluggable photonic biosensors using GRIN fiber collimators. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13749 SN - 1560-2303 VL - 60 IS - 1 PB - SPIE ER - TY - JOUR A1 - Fünning, Tabea A1 - Paul, Martin A1 - Manganelli, Costanza Lucia A1 - Wenger, Christian A1 - Mai, Andreas A1 - Steglich, Patrick T1 - Comparative simulation analysis of photonic ultrasound sensors based on silicon waveguides JF - Scientific Reports N2 - Pressure sensors based on photonic integrated circuits (PIC) offer the prospect of outstanding sensitivities, extreme miniaturization and have the potential for highly scalable production using CMOS compatible processing. PIC-based pressure sensors detect the change in optical properties, i.e. the intensity or phase of the optical carrier wave inside miniaturized waveguide structures. The detection of ultrasound is achieved by engineering the waveguide architecture such that a pressure causes a high change in the effective refractive index of the waveguide. A range of PIC-based pressure sensors have been reported, but a comparison of the sensitivity of the different approaches is not straightforward, since different pressure sensitive waveguide architectures as well as photonic layouts and measurement setups impact the performance. Additionally, the used sensitivity unit is not uniform throughout the different studies, further complicating a comparison. In this work, a detailed simulation study is carried out by finite element modeling of different pressure sensitive waveguide architectures for a consistent comparison. We analyze three different sensor architectures: (A) a free standing membrane located within a tiny air gap above the waveguide, (B) a waveguide located on top of a deflectable membrane as well as (C) a waveguide embedded inside a pressure-sensitive polymer cladding. The mechanical response of the structures and the resulting changes in mode propagation, i.e. the change of the effective refractive index, are analyzed. The waveguide sensitivities in RIU/MPa for different waveguide types (strip, slot) and polarization states (TE, TM) are compared. The results reveal inherent limitations of the different waveguide designs and create a basis for the selection of suitable designs for further ultrasound sensor development. Possibilities for enhancing waveguide sensitivity are identified and discussed. Additionally, we have shown that the studied approaches are extensible to SiN waveguides. Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-20560 VL - 15 PB - Springer Nature ER - TY - CHAP A1 - Bauer, Joachim A1 - Heinrich, Friedhelm A1 - Fursenko, Oksana A1 - Marschmeyer, Steffen A1 - Bluemich, Adrian A1 - Pulwer, Silvio A1 - Steglich, Patrick A1 - Villringer, Claus A1 - Mai, Andreas A1 - Schrader, Sigurd T1 - Very high aspect ratio through silicon via reflectometry T2 - Proceedings of SPIE N2 - 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. Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13758 SN - 1996-756X ER -