Diese Arbeit beschäftigt sich mit der Entwicklung und Verbesserung von Rastersondenmikroskopen durch den Anschluß eines Signalpfades für hochfrequente Wechselfelder (ca. 1 GHz). Dabei entstanden sowohl ein Hochfrequenzrastertunnelmikroskop (HF-STM), als auch ein Hochfrequenzkapazitätsmikroskop (HF-SCM). Das gemeinsame Funktionsprinzip dieser Mikroskope besteht in der Nutzung der Nahfeldwechselwirkungszone als Mischer für die hochfrequenten Signale. Dabei entstehen aus den Eingangssignalen neue Signale anderer Frequenz, die verstärkt und detektiert werden. Beim HF-STM werden diese Signale durch die Nichtlinearität der statischen Strom-Spannungskennlinie des Tunnelsüberganges hervorgerufen. Hieraus ergeben sich zwei neue Nutzungsmöglichkeiten im Vergleich zum herkömmlichen STM: Erstens lassen sich durch Vergleich mit den gleichzeitig aufgenommenen topographischen Bildern elektronische von topographischen Gegebenheiten unterscheiden. Zweitens ist ein Betrieb des HF-STM's auf leitenden Oberflächen möglich, zu denen jedoch keine leitende Verbindung besteht, wie beispielsweise Metallinseln auf einem Nichtleiter-geträgerten Katalysator. Im Falle des HF-SCMs konnte gezeigt werden, daß die detektierten Signale durch die Nichtlinearität der Kapazitäts-Spannungskennlinie des von Spitze und Substrat gebildeten MOS-Kondensators entstehen. Das Mikroskop läßt sich verwenden, um Schwankungen der Oxidschichtdicke oder laterale Dotierprofile in Halbleiterstrukturen abzubilden. Gegenüber dem herkömmlichen SCM bietet die Methode den Vorteil der freien Wahl der Arbeitsfrequenz, wodurch zusätzlich frequenzabhängige Messungen möglich werden. / This work concerns the developement and improvement of scanning probe microscopes by connecting a high frequency signal path (approx. 1 GHz) to the tip of the microscope. This allowed the construction of both, a high frequency scanning tunneling microscope (HF-STM) as well as a high frequency scanning capacity microscope (HF-SCM). The common priciple of the microscopes is the use of the nearfield zone as a mixing device for the high frequency signals. From the input signals new signals at other frequencies are generated, amplified and detected. In case of the HF-STM these signals are caused by the nonlinear current-voltage characteristics of the tunneling junction. The principle permits two new applications: First the comparison between conventional STM-pictures with the newly generated pictures of the same area allows to differantiate between topographic and electronic features of the surface. Second, the new method allows the imaging of conducting surfaces, even if there is no direct conducting conection. An example would be the imaging of metal clusters embedded in a nonconducting surface. In case of the HF-SCM it could be demonstrated that the detected signals are caused by the the nonlinear capacity-voltage dependence of the MOS-capacitor, formed by the substrate and the conducting tip. The microscope can be used to image changes of the oxide layer thicknes or lateral doping profiles in semicoductor devices. In comparison with the conventional SCM the new device is not restricted to one frequency and can therefore be used to carry out frequency-dependent measurements.

This thesis deals with optical synthesis of unmodulated and modulated microwave signals. Generation of microwave signals based on optical heterodyning is discussed in detail. The effect of phase noise of laser on heterodyned output has been studied for different phase noise profiles. Towards this, we propose a generic algorithm to numerically model the linewidth broadening of a laser due to phase noise. Generation of microwave signals is demonstrated practically by conducting an optical heterodyning experiment. Signals ranging in frequency from 12.5 MHz to 27 GHz have been generated. Limitations of optical heterodyning based approach in terms of phase noise performance and frequency stability are discussed and practically demonstrated. A hardware-efficient Optical Phase Locked Loop (OPLL) is proposed to overcome these issues. Phase noise tracking performance of the proposed OPLL has been experimentally demonstrated. Phase noise values as low as -105 dBc/Hz at 10 KHz offset have been achieved. Optical modulators, owing to their extremely low electro-optic response time, can support high frequency modulating signals. This makes them highly attractive in comparison to their microwave counterparts. In this thesis, we propose techniques to generate microwave signals modulated at very high bit rates by down-converting the corresponding modulated optical signals to microwave domain. Down-conversion required for this process is achieved by optical heterodyning. The proposed concept has been theoretically analyzed, simulated and experimentally validated. Amplitude Modulated and ASK modulated microwave signals have been generated as Proof-of-Concept. Limitations posed by OPLL in generation of angle modulated microwave signals by optical heterodyning have been brought out. Schemes overcoming these limitations have been proposed towards generation of BPSK and QPSK modulated microwave signals. Integrated Optics (IO) technology has been studied as a means of implementation of the proposed concepts. IO components like Sinusoidal bends, Y-branch splitters and Electro-Optic-Modulators (EOMs) have been designed towards optical synthesis of modulated microwave signals. Propagation of modulated optical signal through these IO components has also been studied. An all-optic scheme based on Optical Beam Forming is proposed for transmission of QPSK modulated signal. Limitation of phase-shifting based approach, in terms of beam-squint, has been brought out. True-Time-Delay based approach has been proposed for applications demanding wide instantaneous bandwidth to avoid beam-squint. Algorithms / numerical methods required for analyses and simulations associated with the above-mentioned tasks have been evolved. This study is envisaged to provide useful insight into the realization of high-speed, compact, light-weight data transmitting systems based on Integrated Optics for future onboard spacecraft applications. This work, we believe, is a step towards realization of an Integrated Optic System-on-Chip solution for specific microwave data transmission applications.