Stephan Pachnicke – författare

The open access book with the title “Electronic-Photonic Integrated Systems for Ultrafast Signal Processing” is a final report of the same-titled DFG Priority Programme in the emerging field of integrated electronic-photonic systems using novel nanophotonic/nanoelectronic semiconductor technologies. The programme is funded by the Deutsche Forschungsgemeinschaft (DFG) and coordinated by Prof. Christoph Scheytt from Heinz Nixdorf Institute, Paderborn. Over the course of six years and two project phases overall 19 principal investigators and their respective research groups conducted their research in a total of 20 funded projects.The overall objective of the Priority Programme is to address nanophotonic/nanoelectronic technology from a system perspective by investigating fundamental electronic-photonic signal processing concepts, algorithms, and novel integrated system architectures using predominantly photonic processing. By photonic-electronic integration in advanced photonic-electronic semiconductor technologies, such as silicon-on-insulator (SOI), silicon nitride (SiN), and indium phosphide (InP), the limits of electronic signal processing can be disrupted. Ultra-fast and energy-efficient information processing is required in many applications, such as communication systems, cloud computing, artificial intelligence, smart factory, instrumentation, and medical technology. Besides speed and energy efficiency, these systems have unique properties like low-cost, miniaturization, robustness, programmability.The research and the results of the programme can be categorized in three core areas which pertain to:Ultra-broadband electronic-photonic signal processing with bandwidth far beyond electronic bandwidthFrequency synthesis as well as high-speed data converters enabled by ultralow-jitter femto-second-pulse-lasersOptical/THz sensing

Diploma Thesis from the year 2002 in the subject Electrotechnology, grade: 1,0, University of Dortmund (Lehrstuhl fur Hochfrequenztechnik), language: English, abstract: Next generation optical communication systems will be characterized by increasing data rates, high signal powers and dense wavelength division multiplexing (DWDM). In future-optical networks channels will be routed through complex, meshed networks (ASTN, Automatically Switched Transport Networks, ITU-T Recommendation G.808 0/Y.1304). These networks will be able to setup transparent optical paths without converting the optical signals to electrical signals. In all-optical networks the physical impairments and degradation effects play an important role. There is a multitude of degradation effects like dispersion, noise, crosstalk, fiber nonlinearities, polarization dependent loss, etc. To enable a fast setup and the best choice of one of the available paths, the signal quality along the whole transmission distance has to be evaluated very fast. Ideally, only a single figure of merit (FOM), e.g. the bit error rate (BER), will be computed, which incorporates all degradation effects. Therefore it is important to characterize the different physical impairments analytically. Signal distortions can be measured by an eye opening penalty (EOP) and degradation effects due to noise by the optical signal-to-noise ratio (OSNR). The goal is to find and calculate these impairments from the signal parameters (modulation format, data rate, duty cycle, channel spacing, etc.) as well as the route parameters (fiber lengths and parameters, EDFA powers, etc.). Due to the need of fast routing algorithms, time-consuming numerical methods or a complete system simulation are not practical. In addition, it is not possible to linearly accumulate the different degradation effects. The focus of this work is to find analytical or heuristic formulas for each degradation effect. These approximation formulas are compared to the results obtained from a complete simulation of a reference system with the help of the simulation tool PHOTOSS.

Master's Thesis from the year 2001 in the subject Electrotechnology, grade: with distinction, City University London, language: English, abstract: Bragg gratings are important devices for both optical communications andsensing. These devices are used to design very narrow band optical filters, which canbe used in wavelength division multiplexing (WDM). It is also perceived that Bragggratings will be used to compensate the dispersion in modern fibre optictelecommunication networks. Semiconductor gratings are usually integrated intolasers to control the operating wavelength. City University Photonic Modelling Group is a world leading research group onthe use of rigorous numerical techniques to design and optimise advanced photonicdevices for optical communications. The research group has already achieved resultson hypothetical one-dimensional (1-D) and realistic two-dimensional (2-D)structures. In this project a combination of three numerical methods has been used,all of which are rigorous, to simulate realistic three-dimensional (3-D) structures insemiconductor waveguides. The combination of these three accurate methods, thefinite element method (FEM), the least squares boundary residual (LSBR) methodand the transfer matrix method (TMM) turned out to be superior to the widely usedcoupled mode theory (CMT). The numerical study of different Bragg gratings shows interesting dependenciesof the characteristics of the gratings on the different design parameters. The workwas carried out for different mesh distributions, different numbers of mesh divisionsand different computational parameters. Another focus of the work was on thestability of the transmission and reflection coefficients obtained from the LSBRprogram. Furthermore the effect of inaccuracy occurring during the fabricationprocess has been studied. The results of this work have been compared to results found by other groups andfellows. We can say that this project is quite new in the field of reflection spectrumcomputation of realistic 3-D semiconductor Bragg gratings. Up to now only a fewpapers have been published on such 3-D semiconductor gratings.

Next generation optical communication systems will have to transport a significantly increased data volume at a reduced cost per transmitted bit. To achieve these ambitious goals optimum design is crucial in combination with dynamic adaptation to actual traffic demands and improved energy efficiency. In the first part of the book the author elaborates on the design of optical transmission systems. Several methods for efficient numerical simulation are presented ranging from meta-model based optimization to parallelization techniques for solving the nonlinear Schrödinger equation. Furthermore, fast analytical and semi-analytical models are described to estimate the various degradation effects occurring on the transmission line.In the second part of the book operational aspects of optical networks are investigated. Physical layer impairment-aware routing and regenerator placement are studied. Finally, it is analyzed how the energy efficiency of a multi-layer optical core network can be increased by dynamic adaptation to traffic patterns changing in the course of the day.