Microwave Photonics

Devices and Applications

Edited by

Stavros Iezekiel Department of Electrical and Computer Engineering, University of Cyprus, Cyprus

Microwave Photonics

Devices and Applications

Edited by

Stavros Iezekiel Department of Electrical and Computer Engineering, University of Cyprus, Cyprus This edition ﬁrst published 2009 # 2009 John Wiley & Sons, Ltd

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Library of Congress Cataloging-in-Publication Data

Microwave photonics : devices and applications / edited by Stavros Iezekiel. p. cm. Includes bibliographical references and index. ISBN 978-0-470-84854-8 (cloth) 1. Microwave devices. 2. Photonics. 3. Electrooptics. 4. Optoelectronics. I. Iezekiel, Stavros. TK7876.M265 2009 621.38103–dc22 2008052215

A catalogue record for this book is available from the British Library.

ISBN: 978-0-470-84854-8

Set in 10/12pt Times New Roman by Thomson Digital, Noida, India. Printed in Great Britain by CPI Antony Rowe, Chippenham, Wiltshire. Contents

List of Contributors vii Preface xi List of Acronyms xv

Part I Introduction to Microwave Photonics 1 1 Microwave Photonics – an Introductory Overview 3 Stavros Iezekiel

Part II Component Technologies 39 2 Direct Modulation for Microwave Photonics 41 Rajeev Ram and Harry Lee

3 High-power Distributed Photodetectors for RF Photonic Applications 67 Sagi Mathai and Ming C. Wu

4 Photonic Oscillators for THz Signal Generation 85 Andreas Stohr€ and Dieter Jager€

5 Terahertz Sources 111 R. E. Miles and M. Naftaly

Part III Systems Applications 131

6 Analogue Microwave Fibre-optic Link Design 133 Edward I. Ackerman and Charles H. Cox, III

7 Fibre Radio Technology 169 Dalma Novak, Ampalavanapillai Nirmalathas, Christina Lim, and Rod Waterhouse vi Contents

8 Microwave Photonic Signal Processing 191 Jose Capmany, Jose Mora, Daniel Pastor, Beatriz Ortega, and Salvador Sales

9 RF and Microwave Photonics in Biomedical Applications 239 Afshin S. Daryoush

10 Characterization of Microwave Photonic Components 291 Stavros Iezekiel

Index 333 List of Contributors

Edward I. Ackerman Photonics Systems, Inc., 900 Middlesex Turnpike, Building #5, Billerica, MA 01821, USA. Email: [email protected] Jose Capmany Optical and Quantum Communications Group, ITEAM Research Institute, Polytechnic University of Valencia, Camino de Vera, s/n 46022 Valencia, Valencia, Spain. Email: [email protected] Charles H. Cox, III Photonics Systems, Inc., 900 Middlesex Turnpike, Building #5, Billerica, MA 01821, USA. Email: [email protected] Afshin S. Daryoush Department of Electrical and Computer Engineering, Drexel University, Bossone 312, 3141 Chestnut Street, Philadelphia, PA 19104-2875, USA. Email: [email protected] Stavros Iezekiel Department of Electrical and Computer Engineering, University of Cyprus, 75 Kallipoleos Avenue, P.O. Box 20537, 1678 Nicosia, Cyprus. Email: [email protected] Dieter Jager€ Universit€at Duisburg-Essen, ZHO/Optoelektronik, Lotharstr. 55, 47057 Duisburg, Germany. Email: [email protected] Harry Lee Physical Optics and Electronics Group, Research Laboratory of Electronics, Room 26-459, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA. Email: [email protected] Christina Lim ARC Special Research Centre for Ultra-Broadband Information Networks (CUBIN), Department of Electrical and Electronic Engineering, The University of Melbourne, Victoria 3010, Australia. Email: [email protected] viii List of Contributors

Sagi Mathai Electrical Engineering and Computer Sciences and Berkeley Sensors and Actuators Center, 261M Cory Hall, 3-0808, University of California, Berkeley, CA 94720-1770, USA. Email: [email protected] Bob Miles Professor of Semiconductor Electronics, Institute of Microwaves and Photonics, School of Electronic Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. Email: [email protected] Jose Mora Optical and Quantum Communications Group, ITEAM Research Institute, Polytechnic University of Valencia, Camino de Vera, s/n 46022 Valencia, Valencia, Spain. Email: [email protected] Mira Naftaly National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK. Email: [email protected] Ampalavanapillai Nirmalathas ARC Special Research Centre for Ultra-Broadband Information Networks (CUBIN), Department of Electrical and Electronic Engineering, The University of Melbourne, Victoria 3010, Australia; and National ICT Australia, Victoria Research Laboratory. Email: [email protected] Dalma Novak Pharad, LLC, 797 Cromwell Park Drive, Suite V, Glen Burnie, MD 21061, USA; and ARC Special Research Centre for Ultra-Broadband Information Networks (CUBIN), Department of Electrical and Electronic Engineering, The University of Melbourne, Victoria 3010, Australia. E-mail: [email protected] Beatriz Ortega Optical and Quantum Communications Group, ITEAM Research Institute, Polytechnic University of Valencia, Camino de Vera, s/n 46022 Valencia, Valencia, Spain. Email: [email protected] Daniel Pastor Optical and Quantum Communications Group, ITEAM Research Institute, Polytechnic University of Valencia, Camino de Vera, s/n 46022 Valencia, Valencia, Spain. Email: [email protected] Rajeev Ram Research Laboratory of Electronics and Professor of Electrical Engineering, Department of Electrical Engineering and Computer Science, Room 36-491, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. Email: [email protected] List of Contributors ix

Salvador Sales Optical and Quantum Communications Group, ITEAM Research Institute, Polytechnic University of Valencia, Camino de Vera, s/n 46022 Valencia, Valencia, Spain. Email: [email protected] Andreas Stohr€ Universit€at Duisburg-Essen, ZHO/Optoelektronik, Lotharstr. 55, 47057 Duisburg, Germany. Email: [email protected] Rod Waterhouse Pharad, LLC, 797 Cromwell Park Drive, Suite V, Glen Burnie, MD 21061, USA; and ARC Special Research Centre for Ultra-Broadband Information Networks (CUBIN), Department of Electrical and Electronic Engineering, The University of Melbourne, Victoria 3010, Australia. Email: [email protected] Ming C. Wu Electrical Engineering and Computer Sciences and Berkeley Sensors and Actuators Center, 261M Cory Hall, 3-0808, University of California, Berkeley, CA 94720-1770, USA. Email: [email protected]; [email protected]

Preface

Microwave engineering and photonics technology are two areas of electrical engineering that have had a dramatic impact on everyday life, in particular in the fields of communication and sensing. The last few decades have seen optical techniques dominating long haul communications, and optical-fibre-to-the-home deployment is being actively pursued in some regions. The huge bandwidth of optical fibres has acted as the spur to develop techniques such as wavelength division multiplexing and to design optoelectronic components, driver electronics and receiver electronics operating at ever higher speeds. This means that the designers of optical-fibre systems have to now consider microwave design issues when dealing with optoelectronic components and their associated electronics. We have also witnessed phenom- enal growth in wireless communications in order to support an increasingly mobile and nomadic lifestyle, and this has been driven by advances not only in signal processing but also microwave components and systems. Whilst early generations of wireless systems have operated at a few GHz, there is substantial research and development activity in mm-wave wireless technology and this has been supported by the development of radio-over-fibre in which optical networks are used for signal distribution and also mm-wave signal generation. Whatever form future generations of communications networks take, it is clear that the physical layer will continue to be dominated by photonics technology (for wired) and microwave technology (for wireless). The ‘interface’ between microwave and photonics technologies will therefore also be of major importance and this ‘interface’ has created a new interdisciplinary field known as microwave photonics. In order to gain a clearer definition of microwave photonics, it is perhaps best to refer to applications and examples. Whenever one has to consider bit rates of several Gb/s in an optical fibre communication system, then microwave design techniques must be applied to components such as modulators and photodiodes. Thus the application of microwave engineering to the design of high-speed optoelectronic components and optical fibre systems is an example of microwave photonics. However, it is the availability of high-speed optoelectronics and optical fibres that has also opened up the possibility of using optical fibre links to transport microwave signals in applications such as phased array antennas, radio astronomy arrays and distributed antenna arrays for in-building wireless communications. Hence the application of photonics technology and techniques to microwave systems is another example of microwave photonics. As microwave photonics has matured, however, we have seen the emergence of more advanced applications of photonics to microwave engineering, leading to enhanced ‘functionality’. Light modulated at microwave frequencies is now being investigated for medical imaging, and we are also seeing the emergence of ‘microwave photonic signal generation and processing’. The xii Preface primary motivation here is to take advantage of the large time-bandwidth product available from optical fibres. A good example of this is the use of optical fibres (in the form of recirculating loops, and more recently through the use of Bragg grating structures and optical amplifiers) to perform filtering of microwave signals. This area of microwave photonics has since expanded to include the development of microwave oscillators using fibre loops (so- called optoelectronic oscillators) and the implementation of analogue-to-digital converters, photonic ‘time stretch’ and arbitrary waveform generation. In addition, we have seen the use of photonics techniques to generate microwave and mm-wave signals through the realization of optical comb generators and optical phase-locked loops in addition to optical heterodyning. This last technique also forms the basis of THz signal generation, where the primary interest is in using the THz spectrum to explore sensing and imaging applications. (The advantage here is that the wavelengths in the THz part of the spectrum enable spectroscopy of molecules.) In fact the THz spectrum has now begun to enter the domain of microwave photonics, since it occupies the ‘gap’ between microwaves and optics. As such, techniques for THz signal generation from both microwave engineering (e.g. Gunn diodes) and from photonics (e.g. heterodyning) are being explored, and the field uses concepts and component designs originating from both microwaves and optics. From an educational perspective, the fields of microwave engineering and photonics are often taught in separate courses (this being yet another symptom of the modularization of many modern degree courses). It is quite rare to find textbooks let alone courses which treat both in a unified way, and as a consequence the field of microwave photonics tends to be populated by practitioners with a mix of backgrounds – physicists and electrical engineers mostly. Some have come to the topic as microwave engineers, optical engineers or semiconductor optoelectronics specialists, each having to learn something of the others fields. This is challenging, since microwave photonics encompasses physical concepts, devices and systems in two different parts of the spectrum. A microwave photonics engineer needs to be well-versed in electromagnetism, semiconductor electronics and optoelectronics, circuit and optics design and communications theory and systems to name but a few topics. Over time a small community of microwave photonics engineers has developed, as evidenced for example by special joint issues of the IEEE Transactions on Microwave Theory and Techniques/OSA Journal of Lightwave Technology and the development of conferences such as the IEEE Topical Meeting on Microwave Photonics. The time is now appropriate for the publication of books in this field, and some texts have already been published on the topics of analogue links and component technology. The aim of this book is to provide some flavour of the work being carried out in this field, and as such it is more an ‘anthology’ rather than an exhaustive compendium of knowledge. To do full justice to the breadth of work being done under the umbrella of microwave photonics would result in an unwieldy tome and the fast pace of innovation and the generation of new applications would soon require the inclusion of new topics in a future edition. Instead I have sought to provide a snapshot of selected work at both the device level and the application level that gives an indication of how microwave photonics can be applied to the design of high- speed optoelectronics and how such high-speed optoelectronics can be exploited for applications in areas such as wireless communications, medical imaging and measurements. Each of the chapters has been written by experts in these particular areas, and it is hoped that both existing practitioners and researchers new to the field will find something that whets their appetite for future work in this exciting area. Preface xiii

My sincere thanks and appreciation go to the contributing authors who took time out of their busy schedules to write and revise their chapters. In addition, I thank all my students and colleagues (past and present) who have indirectly contributed to the book via discussions on various parts of microwave photonics technology. On the publishing side, I am particularly indebted to Juliet Booker for helping me through the ﬁnal stages of production. Finally, I must thank my family (and especially Kalina) for their constant support and understanding.

Stavros Iezekiel Nicosia, Cyprus October 2008