We present a simple phenomenological theory of polarisation spectroscopy and apply it in an assessing fashion to measurements and detailed theoretical calculations. Onr model serves also to intorproto polarisation spectroscopy... more
We present a simple phenomenological theory of polarisation spectroscopy and apply it in an assessing fashion to measurements and detailed theoretical calculations. Onr model serves also to intorproto polarisation spectroscopy measurements of relative OH concentrations.
Research Interests: Physics and Spectroscopy
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In this document we provide an overview of use-case specific requirements for (future) IoT applications and direct the reader to the pertinent literature.
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Using a femtosecond fiber laser operating at 1560 nm, we have generated both longer and shorter wavelengths in subsequent nonlinear fiber processes. These strategies provide a versatile and rugged light source for spectroscopic sensing.
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ABSTRACT Initial measurements of water vapor temperature by use of a Fourier-domain mode-locking laser were performed in a homogenous charge compression ignition engine. We assessed the potential of this FDML laser in combustion... more
ABSTRACT Initial measurements of water vapor temperature by use of a Fourier-domain mode-locking laser were performed in a homogenous charge compression ignition engine. We assessed the potential of this FDML laser in combustion applications.
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Research Interests: Mechanical Engineering, Optics, Chemistry, Analytical Chemistry, Medical Imaging, and 15 moreFiber Optics, Telecommunications, Photonics, Medicine, Society, Lasers, Optical, Absorption spectroscopy, Light, Temperature, Absorption, Photons, Reproducibility of Results, Nonlinear Optical Spectroscopy, and Thermometers
Time-resolved spectroscopy can be compromised by optical beating, which is inherent to polychromatic light sources and signals. For incoherent light sources, the random interference can partially or completely mask the spectroscopic... more
Time-resolved spectroscopy can be compromised by optical beating, which is inherent to polychromatic light sources and signals. For incoherent light sources, the random interference can partially or completely mask the spectroscopic signature of interest if the time dynamics of the interference are similar to or faster than that of the signature. Part I of this review focused on the theory of this process with an emphasis on thermal light sources, and in this part, four methods to mitigate or circumnavigate the detrimental impact of interference on time-resolved spectroscopy are reviewed: use of light with a controlled, non-stochastic phase, use of narrow-bandwidth light, averaging, and pulse referencing.
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Optical beating of polychromatic light is reviewed and its potential impact on time-resolved spectroscopy is analyzed. In particular, the dependence of the quasi-random beating of thermal light on quantities including average power,... more
Optical beating of polychromatic light is reviewed and its potential impact on time-resolved spectroscopy is analyzed. In particular, the dependence of the quasi-random beating of thermal light on quantities including average power, spectral shape, and spectral width are reviewed.
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A dispersive grating compressor was included in a fiber ring laser to generate an unequally spaced frequency comb spanning approximately 1549-1552 nm. Beating of nearby modes in the comb naturally assigns unique amplitude modulation... more
A dispersive grating compressor was included in a fiber ring laser to generate an unequally spaced frequency comb spanning approximately 1549-1552 nm. Beating of nearby modes in the comb naturally assigns unique amplitude modulation frequencies to each spectral component emitted. The source contains no moving parts. The single-mode fiber-coupled output is directed through hydrogen cyanide gas and detected by a photodiode. A Fourier transform of a 1 ms record yields a spectrum that agrees with results from a grating spectrometer at 0.06 nm resolution. By engineering stable, broadband combs, the technique could result in a universal and simple approach for spectroscopy at almost arbitrary measurement speeds and spectral resolutions limited only by Fourier principles.
Research Interests: Physics, Optics, Quantum Physics, Hyperspectral remote sensing, Medicine, and 12 moreAbsorption spectroscopy, Absorption, Optical physics, Spectrum, Fourier Transform spectroscopy, Fourier transform, Optical Frequency Comb, Single Mode Fiber, Grating, Electrical And Electronic Engineering, Spectral Resolution, and Continuous Wave
In this paper, we present experimental results on optical wireless transmission using commercially available phosphorescent white-light LEDs. To the best of our knowledge, we demonstrate for the first time visible-light links operating at... more
In this paper, we present experimental results on optical wireless transmission using commercially available phosphorescent white-light LEDs. To the best of our knowledge, we demonstrate for the first time visible-light links operating at transmission rates up to 200 Mb/s over typical room distances and at reasonable bit-error-ratios. The experiments were performed using optical filtering at the receiver and on-off-keying as
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The potential of polarization spectroscopy for the detection of trace constituents in sooting combustion was investigated. It was demonstrated that the directionality of the polarization spectroscopy signal can be exploited to efficiently... more
The potential of polarization spectroscopy for the detection of trace constituents in sooting combustion was investigated. It was demonstrated that the directionality of the polarization spectroscopy signal can be exploited to efficiently suppress incoherent interferences, e.g., Rayleigh scattering at soot particles. We also show how polarization spectroscopy compares with laser-induced fluorescence in this type of environment by applying both techniques to atmospheric-pressure, premixed propane/oxygen flames. The acquired signals were spatially resolved along the centerline of the flame, and measurements were conducted at several heights above the burner head and for medium to very high fuel-to-oxidizer ratios. Through our work we found that polarization spectroscopy can be applied even in the presence of large soot fractions. For most conditions, where laser-induced fluorescence suffered from interferences like elastic scattering, spatially filtered polarization spectroscopy signals were virtually background-free, and only for high soot loads did a noticeable background on the latter signal appear. This background likely stems from Mie scattering at very large soot particles.
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The Internet of Things (IoT) is an emerging network superstructure that will connect physical resources and actual users. It will support an ecosystem of smart applications and services bringing hyper-connectivity to our society by using... more
The Internet of Things (IoT) is an emerging network superstructure that will connect physical resources and actual users. It will support an ecosystem of smart applications and services bringing hyper-connectivity to our society by using augmented and rich interfaces. Whereas in the beginning IoT referred to the advent of barcodes and Radio Frequency Identification (RFID), which helped to automate inventory, tracking and basic identification, today IoT is characterized by a dynamic trend toward connecting smart sensors, objects, devices, data and applications. The next step will be cognitive IoT, facilitating object and data re-use across application domains and leveraging hyper-connectivity, interoperability solutions and semantically enriched information distribution. The Architectural Reference Model (ARM), presented in this book by the members of the IoT-A project team driving this harmonization effort, makes it possible to connect vertically closed systems, architectures and ap...
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In this contribution, an abstraction model for communication in distributed automation applications is proposed. This model facilitates a stringent delineation of the application and communication network, and fosters topics such as the... more
In this contribution, an abstraction model for communication in distributed automation applications is proposed. This model facilitates a stringent delineation of the application and communication network, and fosters topics such as the introduction of service-oriented communication functions into automation and the abstraction of heterogeneous communication networks. This is necessary to support the flexibility demands of future industrial applications, realizable with modern communication concepts like Software Defined Networks. The paper proposes a classification of communication requirements, and discusses implementation aspects.
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As identified in the previous chapter, IoT-A has created an “Architectural Reference Model” (IoT ARM) as the common ground for the Internet of Things. The core idea is that the IoT ARM provides a common structure and guidelines for... more
As identified in the previous chapter, IoT-A has created an “Architectural Reference Model” (IoT ARM) as the common ground for the Internet of Things. The core idea is that the IoT ARM provides a common structure and guidelines for dealing with core aspects of developing, using and analysing IoT systems. The first part of this chapter provides a non-exclusive list of the beneficial uses of the IoT ARM. In the second part we focus on the role of the IoT ARM in the architecture development process.
The high-speed modulation capabilities of white light-emitting diodes (LEDs) offer a unique combination of illumination and simultaneous free-room data transmission, and therewith enable a range of novel and promising applications.... more
The high-speed modulation capabilities of white light-emitting diodes (LEDs) offer a unique combination of illumination and simultaneous free-room data transmission, and therewith enable a range of novel and promising applications. However, the optical radiation safety requirements for this dual use of LEDs are currently provided by two standards: free-space optical communication with LEDs is still covered by the application-related part of the laser-safety series, IEC 60825-12, whereas almost all other applications of LEDs, including lighting, are since 2006 covered by the lamp safety standard IEC 62471. Primarily, due to big differences in the underlying safety philosophies, the application by both standards to the same source results in noticeably different assessments and usage regulations. Hereby, the laser-related requirements are most restrictive. However, there is no added hazard for a lamp due to high-speed modulation that happens to convey data. A simple exclusion of LEDs ...
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We provide a systematic analysis of system-of-systems architecture models such as the Smart-Grid Architecture Model and the Reference Architecture Model for Industrie 4.0. This analysis is carried out by utilizing concepts defined in the... more
We provide a systematic analysis of system-of-systems architecture models such as the Smart-Grid Architecture Model and the Reference Architecture Model for Industrie 4.0. This analysis is carried out by utilizing concepts defined in the view model of ISO/IEC/IEEE 42010. Our view-based analysis is then used to derive generalized rules for the generation of new system-of-systems architecture models. We also discuss the relationship of these models with architecture frameworks and how the generalized rules identified can be exploited for the derivation of system-of-systems model kinds.
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We are assessing the potential of multi-color heterodyne spectroscopy for applications to turbulent combustion.
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Using a femtosecond fiber laser operating at 1560 nm, we have generated both longer and shorter wavelengths in subsequent nonlinear fiber processes. These strategies provide a versatile and rugged light source for spectroscopic sensing.
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During the European collaborative project OMEGA, two optical-wireless prototypes have been developed. The first prototype operates in the near-infrared spectral region and features Giga Ethernet connectivity, a simple transceiver... more
During the European collaborative project OMEGA, two optical-wireless prototypes have been developed. The first prototype operates in the near-infrared spectral region and features Giga Ethernet connectivity, a simple transceiver architecture due to the use of on-off keying, a multi-sector transceiver, and an ultra-fast switch for sector-to-sector hand over. This full-duplex system, composed by one base station and one module, transmits data on three meters. The second prototype is a visible-light-communications system based on DMT signal processing and an adapted MAC sublayer. Data rates around to 100 Mb/s at the physical layer are achieved. This broadcast system, composed also by one base station and one module, transmits data up to two meters. In this paper we present the adapted optical wireless media-access-control sublayer protocol for visible-light communications. This protocol accommodates link adaptation from 128 Mb/s to 1024 Mb/s with multi-sector coverage, and half-duplex or full-duplex transmission.
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Transmission of 1 Gbit/s over 100 m of SI-POF is demonstrated. To the authors’ knowledge this sets a new record. The bandwidth limitation of the SI-POF is compensated by spectrally efficient adaptive multiple subcarrier modulation.... more
Transmission of 1 Gbit/s over 100 m of SI-POF is demonstrated. To the authors’ knowledge this sets a new record. The bandwidth limitation of the SI-POF is compensated by spectrally efficient adaptive multiple subcarrier modulation. Introduction With its widespread adoption in mass-markets like automotive and industrial Ethernet the 1 mm PMMA step-index plastic optical fibre (SI-POF) as defined in the IEC 60793-2 norm has been proven to be a robust, low-cost, and easy-to-install transmission medium. These unique features make the SI-POF a highly attractive candidate for in-building networks requiring data rates in the range of 1 Gbit/s (IEEE 1394b, Gigabit-Ethernet) to about 3 Gbit/s (uncompressed HDTV). Due to its large diameter, modal dispersion limits the bandwidth-length product of the SI-POF to approximately 100 MHz × 100 m, a relatively poor value compared to copper cable as well as multimode glass fibre. Recently, several new methods have been proposed to counter this bandwidt...