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Über dieses Buch

The subject "optical signal processing" can and should include all aspects of optics and signal processing. However, that is too large a scope for a textbook that, like this one, is intended as an introduc­ tion to the subject at a level suitable for first year graduate students of electrical engineering, physics, and optical engineering. There­ fore, the subject matter has been restricted. The book begins with basic background material on optics, signal processing, matrix alge­ bra, ultrasound and SAWs, and CCDs. One might argue about this choice of topics. For example, there already exist very good books on matrix algebra. However, matrix algebra is so important in sig­ nal processing, especially in connection with devices such as optical matrix processors, that it was felt that a review was essential. Also, the matrix algebra needed for systolic arrays and parallel computing has made great advances in recent years. My original intention was to write a single-volume textbook cov­ ering most of the fundamental concepts and applications of optical signal processing. However, it soon became apparent that the large amount of material to be included would make publication in a single volume impracticable. Therefore this volume treats the "fundamen­ tals" and a second volume will appear dealing with devices and applications. This textbook was stimulated by a set of short courses that I have directed and lectured since 1976, as well as regular courses that I have taught at Rensselaer Polytechnic Institute since 1974.

Inhaltsverzeichnis

Frontmatter

1. Introduction

Abstract
Until recently, optics had not been considered as part of the electrical engineering curriculum, even though the fundamental laws of electromagnetic waves, which include those in optics, are governed by Maxwell’s equations. The main reason for this was the absence of coherent optical sources equivalent to klystrons or magnetrons for microwaves, or oscillators for lower frequencies. However, the invention of the laser has changed this situation and, as expected, there has been enormous activity in using the optical frequency region for conventional electrical engineering applications, such as optical communication, laser radar and optical signal processing. These applications are in addition to those traditionally belonging to optics, such as photography, spectroscopy, microscopy, and in telescopes, etc. which generally use incoherent light. The “optical revolution” in electrical engineering is not only fueled by the availability of the laser but also by other technical developments such as integrated optics, fiber optics, acousto-optics, electro- and magneto-optics, Fourier optics, a phenomenal need for parallel computation, hence optical computing, systolic arrays, photodetector arrays and charge-coupled devices (CCDs), charge-injected devices (CIDs), focal plane arrays, GaAs technology, very high speed integrated circuits, and the overall desire of society to perform real-time signal processing with faster speed and higher bandwidth.
Pankaj K. Das

2. Optics Fundamentals

Abstract
Optics deals with light waves, which are electromagnetic waves. Electromagnetic waves include not only light waves, but also ordinary alternating current at 60Hz, radio waves, microwaves, infrared, X-rays and γ-rays. Electromagnetic waves obey Maxwell’s equations, which are introduced in Sect. 2.1, which also treats the electromagnetic wave equation followed by the plane-wave solution in homogeneous, linear isotropic space. This is followed by the derivation of Snell’s law and reflection and transmission coefficients using the transmission line approach. To make the discussion self-contained, fundamentals of transmission lines are discussed in Sect. 2.5. The concepts of group and phase velocity are introduced in Sect. 2.7. The subject of Gaussian beam propagation in free space is introduced in Sect. 2.8. To consider Gaussian beam propagation through optical elements, the matrix method of geometrical optics is reviewed first and a discussion of lens aberration is included. The matrix method is then extended to introduce gradient optical fibers. The subjects of step-index fibers and integrated optics are tackled together in Sect. 2.11. Sections 2.12–16 deal with anisotropic media, including electro-optic, acousto-optic and magneto-optic effects. The subject of diffraction is considered in Sect. 2.17, which includes a review of Fresnel and Fraunhofer regions, Fourier optics, gratings, and interferometers. Fundamentals of holography and spatial filtering are also included in this review.
Pankaj K. Das

3. Signal Processing Fundamentals

Abstract
In this chapter, we shall review material relevant to the understanding, design and application of optical and other devices discussed in this book. Signals can be analog, discrete or digital. For the analog case, the time or space variable is continuous. For the discrete case, the time axis is sampled at a fixed interval or for discrete values, even though the amplitude remains analog or continuous. Of course, for a digital system, the time is discrete and the amplitude is represented by a digital number. The spatial signal can also be two- or multidimensional.
Pankaj K. Das

4. Introduction to SAW and CCD Technology

Abstract
The need for and advantages of carrying out real-time signal processing with faster speed and higher bandwidth culminated in the use of SAW and the invention of CCD devices in the 1960s. A major objective of this chapter is to introduce fundamentals of these devices to the reader. Another objective is to discuss applications of this technology in areas such as radar and sonar engineering, image processing, spread spectrum communications systems and filtering in general. Section 4.6 includes a discussion of the relative advantages and disadvantages of SAW and CCD devices and compares them with other signal processing methods, such as digital or optical signal processing. There are fundamental limitations in both of these types of device as well as some suitability to particular applications purpose. A thorough analysis is presented which provides enough information to enable the reader to choose a particular device for a particular purpose. Of course, as the technology advances, these analyses will need to be modified accordingly.
Pankaj K. Das

Backmatter

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