Publications - René Kirrbach

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Publications:

2023

Kirrbach, R.; Schneider, T.: Curved Light Guide Structure, Method for Producing same, and Transmission System, Patent, EP3942341B1, 03.05.2023, priority: 18.03.2020.
[BibTeX][Abstract] [LINK]
A curved light guide structure (10; 20; 30; 50; 60; 70; 80; 90) configured to guide an optical signal (22) within a spectral region, and comprising: end faces (16a, 16b) disposed at two ends of the curved light guide structure; a first main side (12a, 12b) extending between the end faces (16a, 16b), and a second main side (12b, 12a) opposite the first main side (12a,12b) and extending between the end faces (16a,16b); at least a first pass region (181, 182) on the first main side (12a, 12b), the first pass region (181, 182) being configured to receive and transmit an optical signal (22) within the spectral region,wherein the curved light guide structure (10; 20; 30; 50; 60; 70; 80; 90) is configured to guide the optical signal (22) along an axial direction (14) between the end faces (16a, 16b); and at least a second pass region (182, 181) on the second main side (12b, 12a) that is configured to let pass, to form and emit at least part of the optical signal (22) from the curved light guide structure; wherein the first pass region (181, 182) is configured to direct the optical signal (22) to be emitted onto a first end face (16a) of the end faces, wherein the second pass region (182, 181) being associated with a sub-region (44) of the end face (16a); and the part of the optical signal (22) is based on a part (48) of the optical signal (22) that is redirected at the sub-region (44); characterized in that the first pass region (181) is configured to direct the received optical signal (22) to the first end face (16a) of the end faces, thereby performing focusing of the optical signal (22) so that the optical signal (22) redirected from the first end face (16a) is collimated.@misc{Kirrbach:2023_OffAxis_OWC_Patent, title={Curved Light Guide Structure, Method for Producing same, and Transmission System}, author={Kirrbach, R. and Schneider, T.}, year={Patent, European Patent Office, EP3942341B1, 03.05.2023, priority: 18.03.2020}, }
Kirrbach, R.; Deicke, F. ; Faulwaßer, M.; Noack, A.;Schneider, T.: Vorrichtung und Netzwerk zur drahtlosen, optischen Kommunikation, Patent, DE102019208986B4, 04.05.2023, priority: 19.06.2019.
[BibTeX][Abstract] [LINK]
Vorrichtung (10) mit einer Kommunikationseinrichtung (12), die Folgendes aufweist:eine Empfangseinrichtung (14); die ausgebildet ist, um ein erstes drahtloses, optisches Kommunikationssignal (16) durch ein freies Übertragungsmedium zu empfangen, um ein elektrisches Signal (18) basierend auf dem drahtlosen optischen Kommunikationssignal (16) zu erhalten;eine Verarbeitungseinrichtung (22), die ausgebildet ist, um das elektrische Signal (18) zu verarbeiten, um ein verarbeitetes elektrisches Signal (24) zu erhalten; undeine Sendeeinrichtung (26), die ausgebildet ist, um das verarbeitete elektrische Signal (24) in ein zweites drahtloses optisches Kommunikationssignal (28) zu überführen, so dass das zweite drahtlose optische Kommunikationssignal (28) zumindest teilweise dem ersten drahtlosen optischen Kommunikationssignal (16) entspricht, und um das zweite drahtlose optische Kommunikationssignal (28) durch ein freies Übertragungsmedium zu senden;wobei die Vorrichtung (10) als Laufkatze für ein Transportsystem gebildet ist.@misc{Kirrbach:2023_DaisyChain_OWC_Patent, title={Vorrichtung und Netzwerk zur drahtlosen, optischen Kommunikation}, author={Kirrbach, R. and Deicke, Frank and Faulwaßer, Michael and Noack, Alexander and Schneider, T.}, year={Patent, German Patent Office, DE102019208986B4, 04.05.2023, priority: 19.06.2019}, }

2022

Kirrbach, R.; Stephan, M.; Faulwaßer, M.; Schneider, T.; Noack, A.; Deicke, F.: Potentials and Limitations of Multipath Lenses for Optical Wireless Transceivers. In Optical Wireless Communication Conference 2022, 10. Nov. 2022, Jakajima B.V.
Keywords: OWC; multipath lenses; diode lasers; laser sources; optical design; ray mapping; freeform; eye safety; laser safety
[BibTeX][Abstract] [LINK] [PDF] [VIDEO]
The superior modulation bandwidth of laser diodes (LDs) makes them an ideal candidate for transmitters in optical wireless communication (OWC). One of the most important limitations in human-accessible environments is laser safety which limits the transmission power and thereby coverage and range. The average LD power can be increased by means of optical components to reduce the power density or to increase the maximum permissible exposure (MPE). The power density is reduced by increasing the beam diameter and the emission angle e to reduce the impinging optical power onto the human eye. The MPE is the limit value for the laser class defined by IEC 60825-1. Within certain limits, the MPE is influenced by the wavelength λand the size of the apparent source. A large apparent source avoids sharp focus points on the retina. Traditionally, the apparent source and thereby the MPE is increased by using conventional lenses, different kinds of diffusers, LD arrays, or multiple distributed fibers. Recently, a new approach with multipath lenses (MPLs) was demonstrated in a Gbit/s OWC Link.@INPROCEEDINGS{Faulwasser:2021_RotaryTransceiver, author={{Kirrbach}, R. and {Stephan}, M. and {Faulwaßer}, M. and {Schneider}, T. and {Noack}, A. and Deicke, F.}, booktitle={Optical Wireless Communication Conference}, title={Potentials and Limitations of Multipath Lenses for Optical Wireless Transceivers}, year={2022}, month={Nov.}, publisher = {Jakajima B.V.}, }
Kirrbach, R.: Optical Wireless Apparatus and Method for Creating Information Memories, patent disclosure, US020220271845A1, 17.02.2022, priority: 17.02.2021.
[BibTeX][Abstract] [LINK]
An optical wireless apparatus that is implemented for transmitting an optical wireless signal via an optical wireless channel includes: an electronic signal source that is configured to provide a data signal and an optical signal source that is configured to convert the data signal into the optical wireless and to emit the same. The optical wireless apparatus is configured to obtain channel information including information associated with a non-linear channel distortion of the optical wireless signal and to perform adaptation of a modulation of the optical signal source by changing an operating state of the electronic signal source for adapting the non-linear channel distortion and/or to perform adaptation of an operating point of the optical signal source for adapting the non-linear channel distortion.@misc{Kirrbach:2021_AdaptiveTransmitter_OWC, title={Optical Wireless Apparatus and Method for Creating Information Memories}, author={Kirrbach, R.}, year={patent disclosure, US Patent Office, US020220271845A1, 17. Feb. 2022, priority: 17.02.2021}, }
Kirrbach, R., Daten-Kommunikationsmodul, Patent, EP000003807690B1, priority: 06.06.2019, publication: 04.05.2022.
[BibTeX][Abstract] [LINK]
Eine Optik für ein Sende- und oder Empfangs-Element, das ausgebildet ist, in einer Hauptstrahlungsrichtung ein Signal zu emittieren und/oder zu empfangen, umfasst einen aus einem, zur Kommunikationswellenlänge optisch transparenten Material geformten, optischen Körper. Dieser weist eine Kavität, in welcher das Sende-/Empfangs-Element angeordnet ist, auf, wobei zwischen der Kavität und dem optischen Körper eine erste Grenzfläche ausgebildet ist. Weiter umfasst der optische Körper eine gegenüber zu der Kavität ausgebildete zweite Grenzfläche sowie eine seitliche Grenzfläche mit einem Totalreflexionsbereich. Die erste Grenzfläche bildet einen ersten zentralen Linsenbereich sowie einen den ersten zentralen Linsenbereich umgebenden ersten Brechungsbereich aus. Die zweite Grenzfläche bildet einen zweiten zentralen Linsenbereich sowie einen den zweiten zentralen Linsenbereich umgebenden zweiten Brechungsbereich aus. Alle beschriebenen Flächen sind als Freiformflächen definiert, sodass sie beliebig geformt sind. Darüber hinaus ist es denkbar, Fresnel-Strukturen in die Oberflächen einzubringen.@misc{Kirrbach:2022_TirLensepPatent, title={Daten-Kommunikationsmodul}, author={Kirrbach, R.}, year={European Patent Office, EP000003807690B1, 04.05.2022}, }
Kirrbach, R.; Schneider, T.; Stephan, M.; Noack, A.; Faulwaßer, M.; Deicke, F.: Total Internal Reflection Lens for Optical Wireless Receivers. In Photonics, 2022, 9, 276, MDPI, 20.04.2022.
Keywords: free-space optics; FSO; freeform; LiFi; optical concentrator; optical wireless communications; OWC; ray tracing; receiver lens; TIR lens
[BibTeX][Abstract] [DOI] [PDF]
This work considers the use of a freeform total internal reflection (TIR) lens for optical concentration and provides for the first time experimental results in the context of optical wireless communications (OWC). The lens is placed on a surface-mounted device (SMD) avalanche photodiode (APD) to minimize position tolerances and simplify assembly. The lens achieves a concentration ratio of go = 44.7 (16.5 dB) within the FOV center and exhibits an acceptance angle of ±5°. The TIR lens approach is validated by comparing eye diagrams and bit error ratios (BER) of a receiver with and without a TIR lens. For the measurements, non-return-to-zero (NRZ) on-off keying (OOK) signals are transmitted with a data rate of 1.289 Gbit/s.@Article{Kirrbach:2022_TIR_Lens_for_OWC_Receivers, AUTHOR = {Kirrbach, Ren\'{e} and Schneider, Tobias and Stephan, Mira and Noack, Alexander and Faulwa{\ss}er, Michael and Deicke, Frank}, TITLE = {Total Internal Reflection Lens for Optical Wireless Receivers}, JOURNAL = {Photonics}, VOLUME = {9}, YEAR = {2022}, NUMBER = {5}, ARTICLE-NUMBER = {276}, URL = {https://www.mdpi.com/2304-6732/9/5/276}, ISSN = {2304-6732}, ABSTRACT = {This work considers the use of a freeform total internal reflection (TIR) lens for optical concentration and provides for the first time experimental results in the context of optical wireless communications (OWC). The lens is placed on a surface-mounted device (SMD) avalanche photodiode (APD) to minimize position tolerances and simplify assembly. The lens achieves a concentration ratio of go = 44.7 (16.5 dB) within the FOV center and exhibits an acceptance angle of ±5°. The TIR lens approach is validated by comparing eye diagrams and bit error ratios (BER) of a receiver with and without a TIR lens. For the measurements, non-return-to-zero (NRZ) on-off keying (OOK) signals are transmitted with a data rate of 1.289 Gbit/s.}, DOI = {10.3390/photonics9050276}
Kirrbach, R.; Faulwaßer, M.; Stephan, M.; Schneider, T.; Deicke, F.: High Power Eye-Safe Optical Wireless Gigabit Link Employing a Freeform Multipath Lens. In IEEE Communications Letters, 26 (6), IEEE, June. 2022.
Keywords: bit error ratio; eye safety; freeform optics; laser diodes; LiFi; multipath lens; optical diffusers; optical wireless communications; on-off keying
[BibTeX][Abstract] [DOI]
This work experimentally demonstrates for the first time the practical feasibility of a freeform multipath lens (MPL) for optical wireless communications (OWC). The MPL is able to increase the eye safety laser power limit. Our transmitter is laser class 1M and features 190 mW optical output. We transmit 1.289 Gbit/s on-off keying (OOK) data and achieve a bit error ratio (BER) of 10-10 for an optical receiver power of -31.2 dBm. The link range is more than 5 m, depending on the targeted BER. We discuss the pros and cons of MPLs and compare them with diffusers.@Article{Kirrbach:2022_HighPower_EyeSafe_Gigabit_Link, author = {Kirrbach, Ren\'{e} and Faulwa{\ss}er, Michael and Stephan, Mira and Schneider, Tobias and Deicke, Frank}, journal = {IEEE Communications Letters}, keywords = {bit error ratio; eye safety; freeform optics; laser diodes; LiFi; multipath lens; optical diffusers; optical wireless communications; on-off keying}, publisher = {IEEE}, title = {Multipath lens for eye-safe optical wireless communications}, volue = {26}, number = {6}, month = {March}, year = {2022}, url = {https://ieeexplore.ieee.org/document/9743382}, doi = {https://doi.org/10.1109/LCOMM.2022.3162642}, }

2021

Kirrbach, R.; Schneider, T.: Eye-Safe Optical Wireless Communication, patent disclosure, WO002021228697A1, 18.11.2021.
[BibTeX][Abstract] [LINK]
A communication node for optical wireless communication in an optical wireless communication network has the following: an input interface designed to receive a data signal, an optical transmitter designed to convert the data signal into an optical signal having an optical power, separating optics designed to spatially divide the optical signal into a plurality of optical component signals having an associated spectral range, in order to split the optical power over the plurality of optical component signals, at least some of the plurality of spectral ranges being concordant. The communication node is designed to transmit the plurality of optical component signals for the optical wireless communication.@misc{Kirrbach:2021_EyeSafe_OWC_Patent, title={Eye-Safe Optical Wireless Communication}, author={Kirrbach, R. and Schneider, T.}, year={patent disclosure, European Patent Office, WO002021228697A1, 18 Nov. 2021}, }
Kirrbach, R.: Untersuchungen zu linearen optisch-drahtlosen Frontends und applikationsspezifischen Freiformlinsen für die optisch-drahtlose Kommunikation. Dissertation, TU Dresden, Vogt Verlag, 01. Nov. 2021, ISBN: 9783959470513
Keywords: OWC; LiFi; transceiver; LED; OFDM; circuit design; laser diodes; photodiodes; freeform; optical concentrators, multipath lenses
[BibTeX][Abstract][LINK]
This thesis investigates the analog optical wireless frontend (AFE) and application-specific freeform lenses for optical wireless communications (OWC). Besides theoretical considerations, design examples are described, implemented at printed circuit board (PCB) level, and investigated metrologically. The design examples include a linear driver that interfaces multiple light-emitting diodes using a transistor precision current source. The receiver design examples compromise an unbalanced differential transimpedance amplifier (TIA) and a single-ended TIA with post-amplifier. The circuits are characterized with respect to their power consumption, transfer function, and linearity. Additionally, the receiver circuit noise is investigated and measured. Signals modulated by orthogonal frequency division multiplexing (OFDM) are transmitted to evaluate the data transmission characteristics of the AFE. This work reports OFDM data rates of up to 1554 Mbit/s. The transmission is studied as a function of received signal strength, transmitter signal level, emitter operating point, bandwidth, and temperature. Thereby, the work quantifies how future transceivers can benefit from features, such as adaptive operating point adjustment, adaptive bandwidth adjustment, and a special type of adaptive power loading. The design examples are integrated into an Ethernet network using a commercial digital signal processor. Data rate measurements in point-to-point, point-to-multipoint, and multipoint-to-multipoint configurations underline the versatility of the transceiver. In addition, a network-based localization algorithm is applied to deliver location-specific content to mobile users within the network. The key feature of this work is the detailed investigation of freeform optics in the context of OWC. The work presents a design framework for freeform lenses, which is so far unique in terms of Li-Fi. By investigating several design examples, this work explores the potential of freeform optics for OWC. The framework uses ray-mapping algorithms to design transmitter lenses. Methods based on the edge ray principle are used to calculate receiver lenses. Using total internal reflection lenses, the optical efficiency and homogeneity within the field of view can be improved. Another design example is a multi-path lens that transforms an elliptical emission profile into a FOV with a rectangular cross section. With respect to eye safety, the lens allows an increase of the optical transmitter power by 13 dB compared to a transmitter without a lens. This result corresponds to a range improvement by a factor of 4.5. Another design example demonstrates how transmitter and receiver lens are combined into a new single hybrid lens to realize contactless data transmission in rotary applications. Finally, a simulative feasibility study investigates the combination of freeform Fresnel lenses with the considered AFE. The lenses extend the communication range to several tens of meters depending on the AFE configuration. In summary, this work demonstrates that discussed design examples can address various applications very well and thus represent a reasonable alternative to commercial radio frequency technologies. Freeform lenses are the key for an efficient solution with high performance..@phdthesis{Kirrbach:2021_Disseration, author={{Kirrbach}, R.}, title={Untersuchungen zu linearen optisch-drahtlosen Frontends und applikationsspezifischen Freiformlinsen für die optisch-drahtlose Kommunikation}, year={2021}, type={Dissertation}, month={Nov.}, publisher = {Vogt Verlag}, school = {TU Dresden}, isbn={9783959470513}, url={https://www.vogtverlag.de/buecher/9783959470513.html}, }
Faulwaßer, M.; Kirrbach, R.; Schneider, T.; Noack, A.; Deicke, F.: Solderable Multi-Gigabit Optical Wireless Transceiver for Rotary Communication Setups. In Optical Wireless Communication Conference 2021, 28. Sep. 2021, Jakajima B.V.
Keywords: OWC; diode lasers; laser sources; optical design; ray mapping; freeform; eye safety
[BibTeX][Abstract] [LINK] [PDF]
This work presents an optical wireless short-range transceiver for on-axis communication over rotary setups or docking applications. The transceiver is solderable and designed for device integration with a small footprint. Bit error ratio (BER) and signal power measurements show the performance for a rotation setup.@INPROCEEDINGS{Faulwasser:2021_RotaryTransceiver, author={{Faulwaßer}, M. and {Kirrbach}, R. and {Schneider}, T. and {Noack}, A. and Deicke, F.}, booktitle={Optical Wireless Communication Conference}, title={Solderable Multi-Gigabit Optical Wireless Transceiver for Rotary Communication Setups}, year={2021}, month={Sep.}, publisher = {Jakajima B.V.}, }
Kirrbach, R.; Noack, A.; Schneider, T.: Optically Cabled In-Home and Locating Network, patent disclosure, WO002021175638A1, 10.9.2021.
[BibTeX][Abstract] [LINK]
A distributor node which is designed for wireless optical communication in a wireless optical communication network has the following: a first interface for actuating a first wireless optical transceiver for wireless optical communication with a first network subscriber; and a second interface for actuating a second wireless optical transceiver for wireless optical communication with a second network subscriber. The first network subscriber and/or the second network subscriber is an infrastructure device of the wireless optical communication network.@misc{Kirrbach:2021_OpticalInhousNetwork_OWC_Patent, title={Optically Cabled In-Home and Locating Network}, author={Kirrbach, R. and Noack, A. and Schneider, T.}, year={patent disclosure, European Patent Office, WO002021175638A1, 10 Sep. 2021}, }
Kirrbach, R.; Schneider, T.; Faulwaßer, M.; Zielant, K.: Multipath lens for eye-safe optical wireless communications. In Optics Express, Vol. 29, Nr. 19, S. 30208-30222, OSA, Sep. 2021.
Keywords: OWC; diode lasers; laser sources; optical design; ray mapping; freeform; eye safety
[BibTeX][Abstract] [DOI] [PDF]
This article considers the design and use of multipath lenses (MPLs) for optical wireless communications (OWC). The MPL increases the maximum permissible exposure (MPE) for eye safety and allows for an increase of transmission power of small-sized emitters like laser diodes (LDs). A prototype of a freeform MPL has been fabricated and characterized. The MPL allows an increase of the optical transmission power by 13 dB, which corresponds to an improvement in the maximum range by a factor of 4.5. The lens transforms the elliptical emission pattern of an edge-emitting LD into a rectangular field-of-view (FOV) with homogenous power distribution. The transmission efficiency through the MPL is 0.905.@article{Kirrbach:2021_OSA_Multipathlens, author = {Kirrbach, Ren\'{e} and Schneider, Tobias and Faulwa{\ss}er, Michael and Zielant, Krzysztof}, journal = {Opt. Express}, keywords = {Diode lasers; Laser sources; Optical design; Optical wireless communication; Spontaneous emission; Total internal reflection}, number = {19}, pages = {30208--30222}, publisher = {OSA}, title = {Multipath lens for eye-safe optical wireless communications}, volume = {29}, month = {Sep}, year = {2021}, url = {http://www.osapublishing.org/oe/abstract.cfm?URI=oe-29-19-30208}, doi = {10.1364/OE.435890}, }
Faulwaßer, M.; Deicke, F.; Kirrbach, R.; Noack, A.: Drahtloser Datenswitch für isochrone Echtzeitkommunikation, Offenlegungsschrift, DE102019217608A8, 08.07.2021.
Kirrbach, R.; Jakob, B.: Drive Circuit For One or More Optical Transmitter Components, Receiver Circuit for One or More Optical Receiving Components For Optical Wireless Communication, And Method, patent disclosure, WO002021028571A1, 18.02.2021.
[BibTeX][Abstract] [LINK]
The invention relates to a drive circuit for one or more optical transmitter components, which circuit has a controlled current source having a control loop. The control loop is designed in such a way that a transmission characteristic of the drive circuit is at a maximum at a predefined frequency. The invention also relates to a receiver circuit for one or more optical receiving components for optical wireless communication. The receiver circuit has, for example, a compensation circuit which is designed to at least partially compensate for an effect of a capacitance of the one or more optical receiving components, wherein the compensation circuit is coupled to two terminals at least at one of the one or more optical receiving components. The receiver circuit has an amplifier circuit which is designed to obtain an amplified output signal on the basis of a current delivered by the one or more optical receiving components. The compensation circuit is designed, for example, to generate a maximum in a frequency response, in order to at least partially compensate for a low-pass response of the amplifier circuit..@misc{Kirrbach:2021_OWCTransceiverCircuit_Patent, title={Drive Circuit For One or More Optical Transmitter Components, Receiver Circuit for One or More Optical Receiving Components For Optical Wireless Communication, And Method}, author={Kirrbach, R. and Jakob, B.}, year={patent disclosure, European Patent Office, WO002021028571A1, 18 Feb. 2021}, }
Schneider, T.; Kirrbach, R.; Faulwaßer, M.; Noack, A.: Drahtloser Datenbus, Offenlegungsschrift, DE102019214377A1, 25.03.2021.
Kirrbach, R.; Noack, A.; Deicke, F.: Wireless Optical Communication Network and Apparatus for Wireless Optical Communication, patent disclosure, WO002020245049A3, 28.01.2021.
[BibTeX][Abstract] [LINK]
A wireless optical communication network comprises a base station, which is designed for wireless optical communication using a wireless optical signal, and a subscriber apparatus, which is arranged so as to be movable relative to the base station and has a communication device which is designed for the wireless optical communication. The subscriber apparatus further comprises a redirecting device which is designed to redirect at least part of the wireless optical signal between a first direction, between the redirecting device and the communication device, and a second direction between the redirecting device and the base station.@misc{Kirrbach:2020_beamsplitter_patent, title={Wireless Optical Communication Network and Apparatus for Wireless Optical Communication}, author={Kirrbach, R. and Deicke, F. and Noack, A.}, year={patent disclosure, European Patent Office, WO002020245049A3, 28. Jan. 2020}, }

2020

Kirrbach, R.; Faulwaßer, M.; Schneider, T.; Noack, A.; Deicke, F.: Vorrichtung und Netzwerk zur drahtlosen, optischen Kommunikation, Offenlegungsschrift, DE102019208986A1, 24.12.2020.
Kirrbach, R.; Schneider, T.: Curved Light Guide Structure, Method for Producing Same, And Optical Transmission System, patent disclosure, WO002020193312A1, 01.10.2020.
[BibTeX][Abstract] [LINK]
A curved light guide structure, which is configured to guide a spectral range, includes the following: end surfaces arranged at two ends of the ring segment structure; a first main side extending between the end surfaces and a second main side, opposite to the first main side, also extending between the end surfaces; at least one first pass region on the first main side, the first pass region being embodied to receive and pass an optical signal in the spectral range, wherein the curved light guide structure is embodied to guide the optical signal along an axial direction between the end surfaces; and at least one second pass region on the second main side, said second pass region being embodied to pass and emit at least a part of the optical signal from the curved light guide structure.@misc{Kirrbach:2020_OffAxis_v2, title={Curved Light Guide Structure, Method for Producing Same, And Optical Transmission System}, author={Kirrbach, R. and Schneider, T.}, year={patent disclosure, European Patent Office, WO002020193312A1, 1. Oct. 2020}, }
Faulwaßer, M.; Kirrbach, R.; Zimmerling, M.; Seipt, P.; Pietzsch, M.; Noack, A.; Deicke, F.: Li‑Fi TSN Node for Industrial Real-time Communications. Embedded World Conference, Elektronik, Nürnberg, Deutschland, ISBN: 978-3-645-50186-6, 25.-27 Feb. 2020.
Keywords: Li-Fi; TSN; optical wireless communications; real-time; light communication; Ethernet; Industry 4.0; M2M; infrared
[BibTeX][Abstract]
The new Time-Sensitive Network (TSN) standard will create new opportunities to combine critical real-time (RT) traffic with uncritical user data from conventional Ethernet networks. The main strings of these networks will operate at 1 Gbit/s. TSN is still cable-based, which makes it inflexible for mobile applications. For wireless TSN-connectivity, radio-frequency (RF) based technologies like Wi-Fi are no option due to their insufficient latency and bandwidth. However, it was shown that Li-Fi is able to meet RT requirements with high bandwidth. This work introduces a two-port Li-Fi TSN node for 1 Gbit/s full-duplex wireless RT communications. The node includes a processing unit, which makes it possible to connect to external controllers, run higher level protocols like OPC UA or attach non-TSN devices. The work shows how to program embedded designs that make use of Li-Fi and TSN. Bandwidth and latency measurements within a TSN network prove the functionality with mobile devices.@INPROCEEDINGS{Kirrbach:2020_embw_LiFi_TSN, author={Faulwaßer, M. and Kirrbach, R. and Zimmerling, M. and Seipt, P. and Pietzsch, M. and Noack, A. and Deicke, F.}, booktitle={Proc. of Embedded World Conference}, title={Li‑Fi TSN Node for Industrial Real-time Communications}, year={2020}, address={Nueremberg, Germany.}, isbn={978-3-645-50186-6} }
Kirrbach, R.; Faulwaßer, M.; Schneider, T.; Meißner, P.; Noack, A.; Deicke, F.: Monolithic Hybrid Transmitter-Receiver Lens for Rotary On-Axis Communications. In Applied Sciences, Nr. 10, S.1540, MDPI, Feb. 2020.
Keywords: hybrid lens; OWC; Li-Fi; freeform lens; optic design; rotary joint; wireless rotary electrical interface; Gigabit-Ethernet;
[BibTeX][Abstract] [DOI] [PDF]
High-speed rotary communication links exhibit high complexity and require challenging assembly tolerances. This article investigates the use of optical wireless communications (OWC) for on-axis rotary communication scenarios. First, OWC is compared with other state-of-the-art technologies. Different realization approaches for bidirectional, full-duplex links are discussed. For the most promising approach, a monolithic hybrid transmitter-receiver lens is designed by ray mapping methodology. Ray tracing simulations are used to study the alignment-depended receiver power level and to determine the effect of optical crosstalk. Over a distance of 12.5 mm, the lens achieves an optical power level at the receiver of −16.2 dBm to −8.7 dBm even for misalignments up to 3 mm .@Article{Kirrbach:2020_MDPI_hybridlens, author = {Kirrbach, R. and Faulwaßer, M. and Schneider, T. and Meißner, P. and Noack, A. and Deicke, F.}, title = {Monolithic Hybrid Transmitter-Receiver Lens for Rotary On-Axis Communications}, journal = {Applied Sciences}, volume = {10}, year = {2020}, number = {4}, article-number = {1540}, URL = {https://www.mdpi.com/2076-3417/10/4/1540}, ISSN = {2076-3417}, DOI = {10.3390/app10041540} }
Kirrbach, R., Optik für Sende- und/oder Empfangs-Element, Kommunikationsmodul, Arrays aus Kommunikationsmodulen, System aus mehreren Kommunikationsmodulen und Verfahren zur Herstellung einer Optik, Patent, DE102018209368B4 , 02.01.2020.
[BibTeX][Abstract] [LINK]
Eine Optik für ein Sende- und oder Empfangs-Element, das ausgebildet ist, in einer Hauptstrahlungsrichtung ein Signal zu emittieren und/oder zu empfangen, umfasst einen aus einem, zur Kommunikationswellenlänge optisch transparenten Material geformten, optischen Körper. Dieser weist eine Kavität, in welcher das Sende-/Empfangs-Element angeordnet ist, auf, wobei zwischen der Kavität und dem optischen Körper eine erste Grenzfläche ausgebildet ist. Weiter umfasst der optische Körper eine gegenüber zu der Kavität ausgebildete zweite Grenzfläche sowie eine seitliche Grenzfläche mit einem Totalreflexionsbereich. Die erste Grenzfläche bildet einen ersten zentralen Linsenbereich sowie einen den ersten zentralen Linsenbereich umgebenden ersten Brechungsbereich aus. Die zweite Grenzfläche bildet einen zweiten zentralen Linsenbereich sowie einen den zweiten zentralen Linsenbereich umgebenden zweiten Brechungsbereich aus. Alle beschriebenen Flächen sind als Freiformflächen definiert, sodass sie beliebig geformt sind. Darüber hinaus ist es denkbar, Fresnel-Strukturen in die Oberflächen einzubringen.@misc{Kirrbach:2020_TirLensPatent, title={Optik für Sende- und/oder Empfangs-Element, Kommunikationsmodul, Arrays aus Kommunikationsmodulen, System aus mehreren Kommunikationsmodulen und Verfahren zur Herstellung einer Optik}, author={Kirrbach, R.}, year={Deutsches Patent- und Markenamt, DE102018209368B4, Jan. 2020}, }

2019

Kirrbach, R.; Faulwaßer, M.; Jakob, B.; Schneider, T.; Noack, A.: Li-Fi for Augmented Reality Glasses: A Proof of Concept, 2019 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct), Peking, China, pp. 263-268, 2019.
Keywords: OWC; Li-Fi; augmented reality; computer network management; free-space optical communication; optical transceivers
[BibTeX][Abstract] [DOI]
Reliable connectivity is a mandatory requirement for modern augmented reality (AR) glasses. For some applications, current radio frequency-based wireless communication technologies fail to meet sophisticated data rate, latency and interference requirements. This paper presents a proof of concept of using Light-Fidelity (Li-Fi) technology for AR glasses to address these issues. In particular, the paper discusses basic Li-Fi architectures and derives a concept for highspeed, bi-directional Li-Fi connectivity. In order to provide spatially aware content, a network-based localization method is introduced. This approach employs the simple network management protocol (SNMP) and is independent from the Li-Fi transceiver, as long as it has a media access control (MAC) address. The practicability of the developed Li-Fi transceiver is verified by data rate and latency measurements. Data rates of up to 536MBit/s are demonstrated over short distances and 216MBit/s over 5m with a sufficient field of view. The complete setup including our localization algorithm is verified by spatial tracking of the AR glasses. Thereby, we report a login time into the Li-Fi domain of 2.04s on average. @INPROCEEDINGS{Kirrbach:2019_LiFiAR, author={Kirrbach, René and Faulwaßer, Michael and Jakob, Benjamin and Schneider, Tobias and Noack, Alexander}, booktitle={2019 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct)}, title={Li-Fi for Augmented Reality Glasses: A Proof of Concept}, publisher={IEEE}, year={2019}, pages={263-268}, doi={10.1109/ISMAR-Adjunct.2019.00-32} }
Kirrbach, R.; Faulwaßer, M.; Jakob, B.: Non-rotationally Symmetric Freeform Fresnel-Lenses for Arbitrary Shaped Li-Fi Communication Channels. Global LiFi Congress 2019, pp. 103–108. IEEE, Paris, June 2019.
Keywords: OWC; Li-Fi; freeform optics; Fresnel lenses; nonimaging; ray mapping; receiver lens; transmitter lens; optical concentrator
[BibTeX][Abstract] [DOI]
This paper considers the use of non-rotationally symmetric freeform Fresnel lenses for arbitrary shaped optical wireless communication channels. Transmitter and receiver lens design is discussed and design examples for rectangular channels are presented. The optical design procedure includes ray mapping methodology and the edge-ray principle. Optical raytracing simulations with realistic models are used for model validation. @INPROCEEDINGS{Kirrbach:2019_LiFi19, author={Kirrbach, René and Faulwaßer, Michael and Jakob, Benjamin}, booktitle={2019 Global LIFI Congress (GLC)}, title={Non-rotationally Symmetric Freeform Fresnel-Lenses for Arbitrary Shaped Li-Fi Communication Channels}, publisher={IEEE} year={2019}, pages={1-6}, doi={10.1109/GLC.2019.8864138} }
Kirrbach, R.; Jakob, B.; Noack, A.: Introducing Advanced Freeform Optic Design to Li-Fi Technology. In Proc. Photoptics 2019, pp. 248–254. SCITEPRESS, Prague, Feb. 2019.
Keywords: OWC, LiFi, Li-Fi, ray mapping, freeform optics, fresnel Lenses, TIR Lens.
[BibTeX][Abstract] [DOI]
The paper considers the potential of freeform optics for Li-Fi technology and presents design approaches for transmitter and receiver optics using ray mapping methodology and freeform Fresnel lens, respectively. Simulation results are then presented for models validation. @INPROCEEDINGS{Kirrbach:2019_photoptics19, author={Kirrbach, René and Jakob, Benjamin and Noack, Alexander}, title={Introducing Advanced Freeform Optic Design to Li-Fi Technology}, booktitle={Proceedings of the 7th International Conference on Photonics, Optics and Laser Technology - PHOTOPTICS}, year={2019}, pages={248-254}, publisher={SciTePress}, organization={INSTICC}, doi={10.5220/0007471802480254}, isbn={978-989-758-364-3}, issn={2184-4364}, }

2018

Kirrbach, R.; Faulwaßer, M.; Noack, A.: High-Speed Cellular Li-Fi HotSpot for Realtime Applications. In Proc. Wireless Congress 2018: Systems and Applications. Elektronik, München, Nov. 2018.
Keywords: OWC, Li-Fi, HotSpot, MP2MP, P2MP, real-time; low-latency; V2V, V2X, ProfiNET; EtherCAT; Industry 4.0; OFDM, HotSpot
[BibTeX][Abstract]
The proceeding digitalization of our environment leads to continuously increasing data traffic. In addition, future 5G networks must provide low-latency data transfer in the range of Milliseconds to enable future real-time applications like fully autonomous traffic. This requirement is challenging for wireless communications. Moreover, the capacity provided by current radio frequency (RF) based wireless technologies will not be sufficient in the future, because of their limited frequency bands.
The so-called “spectrum crunch” can be faced by introducing new technologies that rely on different carrier wavelengths. Besides intensive research in the field of millimeter-wave based communication, Li-Fi technology becomes more and more popular. Li-Fi utilizes optical wireless communication links that offer both high speed and low latency data transfer trough spatially well-defined communication channels. This allows to design cellular communication networks with minimal inter-channel and inter-cell interference.
This paper discusses different real-time applications to give an understanding about different meanings of “real-time” and shows how Li-Fi can fulfill the requirements. Therefore we introduce a classification of Li-Fi transceivers. In order to prove the practical feasibility for real world applications we present our new Fraunhofer IPMS Li-Fi HotSpot. The system provides high-speed, bi-directional communication with latencies of about 800 μs. By using a DC-OFDM modulation scheme the transceiver is able to provide a continuous net data rate of more than 500 Mbps through its 1 Gbps Ethernet adapter. Data rate and latency measurements in an MP2MP scenario prove the compatibility of our Li-Fi HotSpot for real-time applications like ProfiNET I/O conformity class A.@INPROCEEDINGS{Kirrbach:2018_WC_HotSpot, author={Kirrbach, R, and Faulwaßer, M. and Noack, A.}, booktitle={Proc. of Wireless Congress: Systems And Applications}, title={10 Gbit/s bidirectional transceiver with monolithic optic for rotary connector replacements}, year={2017}, address={Munich, Germany.}, }
Kirrbach, R.; Faulwaßer, M.; Ostermann, R.; Schneider, T.; Noack, A.; Deicke, F.: Automatic Tracking of Li-Fi Links for Wireless Industrial Ethernet, Embedded World Conference, Nürnberg, ISBN:978-3-645-50173-6, Feb. 2018.
Keywords: OWC, Li-Fi, infrared; real-time; 1 Gbps; IrDA; beam steering; IoT; Industry 4.0; M2M
[BibTeX][Abstract]
The ongoing digitalization of our environment leads to continuously increasing data traffic. Especially in industrial environments, automation is an omnipresent trend. Autonomous systems incorporate a rising amount of sensors as well as continuous machine-to-machine (M2M) communication. Wireless communications can simplify the data transmission and enable connectivity to dynamic parts like moving, vibrating or rotating components. Due to the open nature of the communication channel, engineers have to face a number of challenges, e.g. security issues, interferences and regulation of irradiated power. Radio frequency (RF) technologies are used in manifold applications, but in certain scenarios they are still cumbersome, because of signal interference and hard real-time requirements. The so-called Li-Fi technology is ideal for autonomous systems in Industry 4.0 since optical communications offer reliable and high data rate communication links with low-latency characteristics. However, the engineer typically has to face a trade-off between the link’s range, coverage and data rate. This contradiction can be overcome by forming a small, steerable spot. In this paper we present a compact Li-Fi tracking system based on a steerable optical wireless link, which enables real-time full-duplex bi-directional data communication with a data rate of 1.289 Gbit/s. This approach shows the feasibility and handling of an energy efficient wireless link, thanks to its 12-bit-precise beam alignment by using micro mirrors. We describe the optical setup and introduce a tracking algorithm which enables fully autonomous link establishment and thus simple installation. Data rate measurements underline the high performance of the wireless link whereas the system’s mobility is characterized by measurements of the settle time of the steered beam.@INPROCEEDINGS{Kirrbach:2018_embw_AutomatedTracking, author={Kirrbach, R, and Faulwaßer, M. and Osterman, R. and Schneider, T. and Noack, A. and Deicke, F.}, booktitle={Proc. of Embedded World Conference}, title={Automatic Tracking of Li-Fi Links for Wireless Industrial Ethernet}, year={2018}, address={Nueremberg, Germany.}, isbn={978-3-645-50173-6} }
Faulwaßer, M.; Kirrbach, R.; Schneider, T.; Noack, A.: 10 Gbit/s bidirectional transceiver with monolithic optic for rotary connector replacements, 2018 Global LIFI Congress (GLC), Paris, Feb. 2018.
[BibTeX][Abstract] [DOI]
In an effort to evolve connectorless links with optical wireless technology, we present a bidirectional full-duplex optical wireless transceiver with a monolithic optic for rotating links. A small-scale design with a link up to 10 Gbit/s is demonstrated and bit error rate analyzed regarding crosstalk and alignment during rotation. @INPROCEEDINGS{Faulwasser:2021_LiFi19 author={Faulwaßer, Michael and Kirrbach, René and Schneider, Tobias and Noack, Alexander}, booktitle={2018 Global LIFI Congress (GLC)}, title={10 Gbit/s bidirectional transceiver with monolithic optic for rotary connector replacements}, year={2018}, pages={1-4}, doi={10.23919/GLC.2018.8319112} }

2017

Kirrbach, R.; Faulwaßer, M.; Ostermann, R.; Pietzsch, M.; Schneider, T.; Noack, A.: Secure Full Capacity Multi-Cell Communication with Li-Fi Systems, Wireless Congress: Systems And Applications, München, ISBN:978-3-645-50171-2, Nov. 2017.
Keywords: Li-Fi; OWC; P2M; P2MP; P2P; secure; 1 Gbit/s; 1000Base-T; Ethernet; EtherCat; mobile; M2M; IoT; Industry 4.0
[BibTeX][Abstract]
Steady multiplication of data traffic over years forces to seek for new technologies. Image processing in production lines and extended logging of sensor clouds are key drivers of high bandwidth processes and quality control. Besides machine-to-machine (M2M) communication, human-machine-interfaces (HMI) are another emerging topic. In the case of augmented and virtual reality environments a guaranteed bandwidth is mandatory. To achieve the required mobility, using wireless links is the inevitable result.
Radio frequency technologies within 2.4 GHz and 5 GHz bands have already reached their limits and struggle in environments with multiple devices caused by interferences. On the first glance raising frequency would be the straightforward option, but this leads to even increased physical interaction and absorption by objects. The alternative is using light with new technology to setup Li-Fi instead of Wi-Fi links. From a physical view light provides a potential bandwidth of more than 300 THz. Moreover, light remains in rooms which adds physical security and in parallel the information for atto cell localization. However, in contrast to RF the optical wireless communication links requires new strategies to roll out spatial aware connectivity.
This paper presents a Li-Fi system which creates communication hotspots up to 1 Gbit/s over nearly 20 meters. Setups with multiple cells for bi-directional point-to-multipoint (P2M) communication are shown. Network architectures for light communication are discussed by highlighting differences in M2M and HMI link design. Especially, this paper underlines the design of optical elements and how to optimize a link depending on the application scenario. The measurements of a setup with P2M cells and point-to-point (P2P) links show the usage of Li-Fi and the feasibility to provide full area coverage. @INPROCEEDINGS{Kirrbach:2017_WC_HotSpot author={Kirrbach, R. and Faulwaßer, M. and Ostermann, R. and Pietzsch, M. and Schneider, T. and Noack, A.}, booktitle={Proc. of Wireless Congress: Systems And Applications}, title={10 Gbit/s bidirectional transceiver with monolithic optic for rotary connector replacements}, year={2017}, isbn={978-3-645-50171-2}, }

University work:

Master’s Thesis: Kirrbach, R.: Entwicklung und Simulation einer Kollimator- und Fokusoptik für die optische drahtlose Datenübertragung, Master’s thesis, TU Dresden, 2017.
Keywords: Li-Fi; OWC; transmitter lens; receiver lens; optical concentrator; CPC; DTIRC
[BibTeX][Abstract]
Steady multiplication of data traffic over years forces to seek for new technologies. Image processing in production lines and extended logging of sensor clouds are key drivers of high bandwidth processes and quality control. Besides machine-to-machine (M2M) communication, human-machine-interfaces (HMI) are another emerging topic. In the case of augmented and virtual reality environments a guaranteed bandwidth is mandatory. To achieve the required mobility, using wireless links is the inevitable result.
Radio frequency technologies within 2.4 GHz and 5 GHz bands have already reached their limits and struggle in environments with multiple devices caused by interferences. On the first glance raising frequency would be the straightforward option, but this leads to even increased physical interaction and absorption by objects. The alternative is using light with new technology to setup Li-Fi instead of Wi-Fi links. From a physical view light provides a potential bandwidth of more than 300 THz. Moreover, light remains in rooms which adds physical security and in parallel the information for atto cell localization. However, in contrast to RF the optical wireless communication links requires new strategies to roll out spatial aware connectivity.
This paper presents a Li-Fi system which creates communication hotspots up to 1 Gbit/s over nearly 20 meters. Setups with multiple cells for bi-directional point-to-multipoint (P2M) communication are shown. Network architectures for light communication are discussed by highlighting differences in M2M and HMI link design. Especially, this paper underlines the design of optical elements and how to optimize a link depending on the application scenario. The measurements of a setup with P2M cells and point-to-point (P2P) links show the usage of Li-Fi and the feasibility to provide full area coverage. @MastersThesis{Kirrbach:2016_Diplom, author = {{Kirrbach}, R.}, title = {Entwicklung und Simulation einer Kollimator- und Fokusoptik für die optische drahtlose Datenübertragung}, school = {TU Dresden}, address = {Dresden, Deutschland}, month = {April}, year = {2016}, type = {Master's Thesis}, }
Studienarbeit: Kirrbach, R.: Entwicklung einer Methode zur dynamischen Auslenkung eines optisch drahtlosen Kommunikationslinks, Studienarbeit, TU Dresden, March 2016.

Advised Thesis:

Dix, M.: Untersuchung eines Silizium-Photomultipliers für die optisch-drahtlose Kommunikation., Diplomarbeit (FH), HTW Dresden, 2022.
Examiner: Prof. Dr.-Ing. Tim Baldauf
Advisors: Dr.-Ing. René Kirrbach
Jakob, B.: Entwicklung eines analogen 100Mbit/s-Transceiver-Frontends für die LI-FI-Kommunikation mit harten Echtzeitanforderungen, Diplomarbeit, TU Dresden, 2020.
Examiner: Prof. Dr.-Ing. habil. Wolf-Joachim Fischer
Advisors: Dipl.-Ing. René Kirrbach
Rödel, J.: Modellierung eines Li-Fi Transceivers zur optischen Freiraumdatenübertragung, Bachelor Thesis, TU Nürnberg, 2020.
Examiner: Prof. Dr.-Ing. habil. R. Engelbrecht
Advisors: Dipl.-Ing. René Kirrbach
Spundflasche, M.: Entwurf eines analogen Hochgeschwindigkeits-Frontends für die optische drahtlose Kommunikation, Bachelor Thesis, Hochschule Koblenz, 2019.
Examiner: Prof. Dr. Uwe Gärtner
Advisors: Dr.-Ing. Alexander Noack; Dipl.-Ing. René Kirrbach
Jakob, B.: Entwicklung eines analogen 100Mbit/s-Transceiver-Frontends für die LI-FI-Kommunikation mit harten Echtzeitanforderungen, Studeinarbeit, TU Dresden, 2017.
Examiner: Prof. Dr.-Ing. habil. Wolf-Joachim Fischer
Advisors: Dipl.-Ing. René Kirrbach