Fiber-optic Bragg-Grating sensors are often the only possibility to perform measurements under adverse environmental conditions, ionizing radiation among them. However, up to now no basic research has been carried out to determine the influence of ionizing radiation on the operativeness of Bragg-Grating-Sensors. Within this work gratings of type I have been written into 3 different singlemode-fibers, with different Ge-content, one of them hydrogen-loaded. Various kinds of ionizing radiation (electrons, photons, He-nuclei) of various energy have been applied to the gratings and grating-temperature-sensors with doses up to 90 MGy. Changees of grating-properties have been monitored before and after irradiation. Experiments show only slight increase of the Bragg-wavelength within the measurement-precision of 1E-03 nm. According to these changes which were also estimated by theoretical considerations, typical applications for grating-sensors with exposure to ionizing radiation have been examinded to tell whether the sensors will meet the specific demands of the respective application.

In this thesis two methods for the manufacturing of optical elements for the monolithic integration in CMOS image sensors are described. Polymeric micro colour filters and refractive micro lenses are presented. The colour filters were made of polyimid thin films with the colours Cyan, Yellow and Magenta. 9 x 9 um^2 filters were deposited on previously planarised CMOS substrates. Optical constants are measured by spectroscopic ellipsometry. The optical constants were used to calculate the colour sensor responses which are in good agreement with the experimental values. Raytracing calculations are used to evaluate the improvement of the responsivity by the use of microlenses. It is shown that the architecture of the pixel layout have to be considered to adapt the lens parameters. For the fabrication of the lenses Polymethyl-Methacrylat (PMMA) was used as a hight transparent material. By the melting of PMMA structures the lenses were obtained. A microlens array was deposited on a glass plate to determine the focal length by the following procedure. By illuminating the microlens array with laser light the focused beam was analysed with a microscope objective. It is estimated that the improvement in responsivity could be as high as 30 % with such a PMMA microlens array.

Die vorliegende Arbeit behandelt schwerpunktmäßig die Technologie und Charakterisierung von Single- und Dual-Gate- InAlAs/InGaAs/InP Heterostruktur-Feldeffekt-Transistoren für Gate-Längen im unteren Submikron Bereich (90 nm < LG < 400 nm). Auf der Basis bereits ausreichend erprobter Transistorschichten ist die vorliegende Arbeit als wissenschaftlicher Beitrag zu verstehen, der die Optimierung der o.g. Bauelemente nahezu ausschließlich mit Methoden der Strukturierungstechnik verfolgt. Die Charakterisierung der hergestellten HFET umfaßte sowohl das Gleich- als auch das Wechselspannungsverhalten. Die Hochfrequenzcharakterisierung basierte dabei auf der Kleinsignalparameteranalyse einschließlich der Kleinsignalersatzschaltbildbestimmung im Frequenzbereich 45 MHz < f < 40 GHz. Für die Herstellung der Bauelemente und hierbei insbesondere für die der Gate-Kontakte (sogenannte T-Gate oder Mushroom-Gate-Kontakte) wurde die Elektronenstrahllithographie als zentrales Strukturierungswerkzeug eingesetzt. Dabei sind eine im Fachgebiet neu beschaffte Belichtungsanlage erstmals in Betrieb genommen, und sämtliche dazu notwendigen Lithographieprozesse entwickelt worden. Als herausragendes Resultat dieses Teils der Arbeit konnte dabei ein völlig neuartiges Belichtungsverfahren erfolgreich vorgestellt werden. Auf der Basis detaillierter Untersuchungen zur Abhängigkeit der Proximity-Funktion Pf(r) von der Elektronen-Beschleunigungsspannung Uacc im Fotoresist gelang die Entwicklung eines Lithographieprozesses für Mushroom-Gate-Kontakte bei extrem niedrigen Werten von Uacc = 10 kV. Durch die gleichzeitige Optimierung des Fotoresist-Systems konnte darüber hinaus die in der Literatur für Mushroom-Gate-Kontakte bekannte aufwendige Mehrfachbelichtung erstmals erfolgreich auf einen einzelnen Belichtungsschritt zurückgeführt werden. Die Funktionstüchtigkeit des neu entwickelten Verfahrens konnte anhand von realen Bauelementdaten demonstriert werden. Die mit Hilfe dieser Technik hergestellten Single-Gate HFET (LG = 0.2 µm) zeigten Grenzfrequenzen von fT = 126 GHz bzw. fmax = 204 GHz. Auch die in der Literatur bekannten Mehrfachbelichtungsprozesse für T-Gate-Kontakte wurden im Rahmen dieser Arbeit optimiert. Auf der Basis einer HFET-Schicht mit sehr guten Transportdaten gelang dabei durch die Einführung eines Doppelbelichtungsprozesses die Herstellung von 0.2 µm-Single-Gate HFET mit Grenzfrequenzen von fT = 181 GHz und fmax = 224 GHz. In bezug auf die Transitfrequenz zählt der erzielte Wert bis zum Zeitpunkt dieser Arbeit zu den Weltbestdaten. Ein weiterer Schwerpunkt dieser Arbeit bildete die Herstellung und Charakterisierung von Dual-Gate HFET in bezug auf die Stoßionisation, deren Auftreten infolge der Steuer-spannungen für InAlAs/InGaAs/InP-HFET typisch ist. Eine ausführliche Analyse sowohl des Gleich- als auch Wechselspannungsverhaltens von Dual-Gate HFET-Kaskoden lieferte erstmals Kenntnisse darüber, die Stoßionisation im Bauelementkanal lokal mit Hilfe des zweiten Gate-Kontaktes gezielt zu beeinflussen. Hierbei konnte richtungsweisend ein neuer Transistortyp entwickelt werden, der für UG2S = 0 V erstmals eine lokale Unterdrückung der Stoßionisation im Kanalbereich unterhalb des mit dem hochfrequenten Signals beaufschlagten ersten Gate-Kontaktes ermöglichte. In einem ansonsten für Single-Gate HFET in bezug auf die Stoßionsation kritischen Arbeitspunkt (UG1S = - 0.5 V, UDS = 3 V) konnten so beim Dual-Gate HFET sehr gute Bauelementdaten erzielten werden (fT = 112 GHz, fmax = 253 GHz, Fmin = 1.01 dB @ 12 GHz, Rn = 40.5 W). Schließlich konnte die Funktionstüchtigkeit der für die Herstellung von Dual-Gate-HFET entwickelten Prozesse insgesamt durch hervorragende Bauelementdaten belegt werden. Für 0.1 µm Dual-Gate HFET sind Weltbestdaten in bezug auf die Hochfrequenzeigenschaften erzielt worden (fT = 141 GHz bzw. fmax = 350 GHz).

This work describes the development and the realisation of travelling-wave photodetectors for the millimeterwave regime. The used travelling-wave concept for the realised optoelectronic devices omits RC-time limitation, which is valid for traditional high-speed photodetectors. To overcome this limitation, the travelling-wave photodetector uses wave propagation effects for the optical input, the optoelectronic conversion, and for the electrical output. The travelling-wave photodetector is fabricated in the InGaAlAs material system lattice-matched to InP using a molecular beam epitaxy. This material system is suited for operation at 1.3 µm to 1.55 µm optical wavelength. The realised devices consist of a coplanar Schottky-contact electrical transmission line. The optical waveguide is located underneath the centre conductor inside the mesa. The interaction between optical waves and electrical waves is realised using an optical absorbing layer. A reverse-biased Schottky-diode between centre conductor and outer conductor separates electrons and holes which are generated in the optical absorbing layer generating a current on the electrical transmission line. This work describes several tools, which are developed for the simulation of travelling-wave photodetectors. The simulation tools allow the calculation of the local optical intensity inside the optical waveguide with BPM and analytical methods. The optical intensity is used to calculate the distributed photo current, which is generated in the distributed photo current source due to carrier generation. The current of this distributed current source is finally used to calculate the currents and voltages of the distributed equivalent circuit of the coplanar electrical waveguide. The realised simulation tools allow a complete description of the optoelectronic conversion of the travelling-wave photodetector including optical input, electrical output, and optoelectronic conversion including wave propagation effects. The simulation tools are used to optimise the travelling -wave photodetector. The simulations are validated using results from different characterisation methods. Two optoelectronic measurement setups for generation of optical heterodyne signals with beating frequencies of up to 60 GHz are realized and used for this work. Several new material systems are developed for the fabrication of travelling-wave photodetectors. The realised devices are the first InP travelling-wave photodetectors with an absorption length of approx. 900 µm for operation at 60 GHz with 1.3 µm to 1.55 µm optical wavelength. Saturation effects are not visible at 60 GHz for optical input powers of up to 12.5 dBm due to the distributed absorbing layer. The realised travelling-wave photodetectors have a efficiency of 0.23 A/W at 1.55 µm optical wavelength and operation at 60 GHz. A comparison with other high-speed photodetectors shows, that the travelling-wave photodetector belongs to the most powerful optoelectronic converters in the millimeterwave regime.

The optical monitoring of the automobile passenger interior compartment is concerned with applications based on optical coverage and image processing in order to provide various functionalities. The emphases of this thesis are optical occupant state recognition and optical interior protection. The interior protection is an integral part of the car alarm system and must be able to detect unauthorized entry. A significant judgement criterion apart from the high detection rate of penetrating objects is a low false alarm rate, which should be achieved using a high spatial resolution of an optical system. Additionally the power dissipation of car alarm systems must be extremely low. This can be obtained when employing modern CMOS image sensors. The task of occupant state recognition arose from the unresolved problem of rear facing infant seat detection and Out-of-Position detection. Tragic accidents involving rear facing infant seats placed in the passenger seat have exemplified the necessity for the detection of infant seats and other critical situations. Optical occupant state recognition encompasses seat occupancy, infant seat detection, and Out-of-Position detection, which up until now have been realized separately - if at all. The critical requirements of this application are adaptability to strongly varying environmental conditions and fast response time. Optical systems for use in passenger compartment monitoring have not yet been the subject of ex tensive research. By employing cameras based on CMOS image sensors the optical stimuli within the vehicle are measured. In order to enable several applications with one system, the position of the camera(s) and the optical influences at this position are examined. In the case of the optical interior protection, algorithms have to be developed enabling the detection of the penetration of objects. Due to the restriction of low power dissipation, these algorithms should not be too complex. The integration of on-chip preprocessing and other electronic features can be combined to make CMOS image sensors power efficient. For optical occupant state recognition concepts with a low cost of computation have to be developed, which are also capable of working in conjunction with the interior monitoring. Thus a high frame rate has to be obtained with these systems. In addition algorithms are necessary that can determine the status of each respective seat. Since the optical occupancy state recognition is a security-sensitive application, additional algorithms are examined that detect very accurately (up to object recognition) the occupation state of the vehicle.

A novel electrostatically driven silicon Micro Scanning Mirror for one and two dimensional deflection of light is presented. A special configuration of the driving electrodes allows the use of small electrode gaps without restricting the deflection of the plate geometrically. Two dimensional deflection is obtained by a gimbal mounting of the mirror plate. The modelling of the actuator is done by analytical and numerical calculations. For the fabrication of the actuators a CMOS compatible process has been developed. The mechanical elements are patterned in a 30 um thick layer of single crystal silicon. Using the ASE process 4 - 5 um wide trenches are etched into this layer with almost perpendicular sidewalls. In the case of the 2D-Scanner filled isolation trenches are used which allow to excite the two oscillations independently. 36 1D-variants have been designed and characterized. The scanning frequencies cover the range from 0.14 kHz up to 32 kHz. The mirror plates are quadratic with a side length between 0.5 mm and 3.0 mm. Synchronizing the driving voltage with the mechanical oscillation it is possible to achieve a stable oscillation. For large deflection angles a linear dependence of the deflection angle on the driving voltage has been observed. A mechanical deflection angle of up to +/-15° is achieved at a driving voltage of 20 V only, proving the high effectiveness of the driving principle. The performance of the 2D-scanner is demonstrated by three variants. Various Lissajous patterns with a frequency ratio between 1:1 and 13:1 have been generated. Investigations regarding the mechanical performance of the actuators have been carried out. The actuators have a shock resistance of more than 1000 g. Long run tests at a deflection angle of +/-15° mechanical with a duration of more than 10^9 have been performed. The characteristics of the devices did not change. Because of its performance the novel actuator is suitable to replace conventional scanners in a large variety of applications.

Im Rahmen der seit ca. 1980 platzgreifenden Miniaturisierung wird es immer interessanter, kostengünstige miniaturisierte Funkgeräte für verschiedene Kommunikationszwecke auch in Gebäuden einzusetzen. Zu erwähnen sind hier vor allem moderne Funktelefone, zunehmend werden aber auch auch Funkstrecken zur Datenübertragung in der Industrie wie auch in privaten Haushalten eingesetzt. Funkübertragung in Gebäuden ist keineswegs unkritisch. Neben gewollten und unbeabsichtigten elektromagnetischen Emissionen stört vor allem die Streuung des elektromagnetischen Feldes an verschiedenartigen Objekten, die in Gebäuden in hoher Dichte vorhanden sind. Der Funkkanal im Gebäude wird in der Arbeit definiert und seine Berechnung in Antennen- und Ausbreitungsproblem aufgeteilt. Rotationssymmetrische Sende- und Empfangsantennen können so unabhängig vom Ausbreitungsproblem simuliert werden. Für die Antennen- und Ausbreitungssimulation wird je ein hybrides Zeitbereichsverfahren vorgestellt. Homogene Gebiete werden dabei mit der schnellen Diskreten Wellengleichung behandelt, Diskontinuitäten mit dem Yee-Schema diskretisiert. Die Verfahren werden unter Verwendung diskreter Feldoperatoren hergeleitet und in bezug auf Dispersion und Genauigkeit untersucht. Absorbierende Randbedingungen werden eingeführt und analysiert. Zur Verifikation der Antennensimulationsverfahren wurden Simulationen für Dipolantennen, eine Disconeantenne und eine koaxial gespeiste Monopolantenne durchgeführt und mit Meßdaten bzw. im Fall der Dipolantenne mit Ergebnissen eines anderen Simulationsverfahrens verglichen. In zwei Testszenarien wurden Transmissionsfaktoren von Funkkanälen in Gebäuden berechnet und Meßergebnissen gegenübergestellt. Die Übereinstimmung ist im Rahmen der für diese kritischen Simulationen zu erwartenden Genauigkeit gut. Die vorgestellten Zeitbereichsverfahren gestatten die Berechnung von Funkkanalimpulsantworten mit sehr hoher Zeitauflösung, wie sie in Forschung und Entwicklung benötigt werden. In Zukunft werden Zeitbereichssimulationen für Funkkanäle immer attraktiver werden, besonders dann, wenn die in der Vergangenheit beobachtete Leistungssteigerung bei Kleincomputern anhält. Doch auch mit heutigen Computern werden angemessen kurze Rechenzeiten bei sehr guten Ergebnissen erreicht.

Ultrasonic imaging uses higher ultrasound frequencies and power levels to achieve better spacial resolution and image quality. Potential hazard for patients have to be evaluated on the basis of relevant acoustic parameters. Measurements of the acoustic pressure with piezoelectric hydrophones is only reliable up to 40 MHz because of minimum sensor size. This work improves a pizooptical measurement method for acoustic pressure. Acoustic pressure changes the refractive index of water. This is determined by measuring laser power, reflected at a fiber/water interface. To improve calibration uncertainty for that kind of measurement to the level of piezoelectric hydrophones (11% - 14%) was the primary goal. Therefore a piezooptic fiber hydrophone with single mode fiber and single mode light source (laser diode) is developed. The active area of the used single mode fiber type has a diameter of 5 µm. Since the fiber influences sound field propagation due to reflection and diffraction, sensitivity of the device is frequency dependent. These effects are compensated by mathmatic modelling. By calculaing the exact curve progression of the factor of reflection depending on the refractive index gradient at the fiber/water interface, calibration uncertainty is improved from 18% to below 11%. Results are validated by intercomparison with several calibarted piezoelectric hydrophones. Measurements are carried out on different ultrasound imagaing systems.

The PhD thesis deals with the topic of thermal radiation in the microwave region of the electromagnetic spectrum in the field of automatic fire detection. The thesis shows that it is possible to detect fires by their thermal radiation in the microwave region and that the thermal radiation of different fire materials depend on the observed frequency, so that it is possible to distinguish the fire materials. The thesis contains the physical basics of thermal radiation, especially in the microwave region. It further describes the developed measuring device that is able to measure the power of the thermal radiation in the frequency range between 2 GHz and 40 GHz, the setup for the standardized test fires according to EN54 and the measuring results.

Knowledge acquisition is the most important part in the development of expert system. It deals with extracting knowledge from sources of expertise and transferring it to a knowledge base. Knowledge acquisition is major research field in knowledge engineering and still the most difficult and error-prone task for knowledge engineer while building an expert system. This situation influences the performance of the knowledge due to the quality of information and the reduction of error possibility. It is not an easy task to acquire knowledge from human expert not trained in knowledge engineering. The performance of the knowledge is performed by interaction between experts and knowledge engineer or machine during acquisition process. In most rule-based expert system, building of rules can easily be done. Knowledge Engineer or expert does not have to do any work specifying rules and how they are linked to each other. Sometime the knowledge engineer or expert can reference rules or facts that have not yet been created. It seems to be a simple and an instant work. The problem due to the performance of the knowledge will not occur until the number of rules is getting higher. Some problem may appear in the form of inconsistent rules, unreachable rules, redundant rule and rotating chain of rules. In order to solve that problem and to achieve that mentioned performance, a rule-based knowledge acquisition system using Ternary Grid is developed. This system acquires knowledge from human expert using grid or matrix system. Ternary Grid represents a model of rule-based knowledge in a grid or matrix format.