NANOPHOTONICS WITH SURFACE PLASMONS Advances in NANO-OPTICS AND NANO-PHOTONICS Series Editors Satoshi Kawata Department of Applied Physics Osaka University, Japan Vladimir M. Shalaev Purdue University School of Electrical and Computer Engineering West Lafayette, IN, USA NANOPHOTONICS WITH SURFACE PLASMONS Edited by V.M. SHALAEV Purdue University School of Electrical & Computer Engineering Indiana, USA S. KAWATA Department of Applied Physics Osaka University, Japan AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK OXFORD PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO Elsevier Radarweg 29, PO Box 211, 1000 AE Amsterdam, The Netherlands The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, UK First edition 2007 Copyright r 2007 Elsevier B.V. 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Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made. Library of Congress Cataloging in Publication Data A catalogue record for this book is available from the Library of Congress. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library. ISBN-13: 978-0-444-52838-4 ISBN-10: 0-444-52838-5 ISSN: 1871-0018 For information on all Elsevier publications visit our website at books.elsevier.com Printed and bound in The Netherlands 07 08 09 10 11 10 9 8 7 6 5 4 3 2 1 Preface There is an undeniable and ever-increasing need for faster information processing and transport. Many believe that the current electronic tech- niques are running out of steam due to issues with RC-delay times, meaning that fundamentally new approaches are needed to increase data processing operating speeds to THz and higher frequencies. The photon is the ultimate unit of information because it packages data in a signal of zero mass and has unmatched speed. The power of light is driving the photonic revolution, and information technologies, which were formerly entirely electronic, are increasingly enlisting light to communicate and provide intelligent control. Today we are at a crossroads in this technol- ogy. Recent advances in this emerging area now enable us to mount a systematic approach toward the goal of full system-level integration. The mission that researchers are currently trying to accomplish is to fully integrate photonics with nanotechnology and to develop novel photonic devices for manipulating light on the nanoscale, including mol- ecule sensing, biomedical imaging, and processing information with unparalleled operating speeds. To enable the mission one can use the unique property of metal nanostructures to ‘‘focus’’ light on the nano- scale. Metal nanostructures supporting collective electron oscillations – plasmons – are referred to as plasmonic nanostructures, which act as optical nanoantennae by concentrating large electromagnetic energy on the nanoscale. There is ample evidence that photonic devices can be reduced to the nanoscale using optical phenomena in the near field, but there is also a scale mismatch between light at the microscale and devices and processes at the nanoscale that must first be addressed. Plasmonic nanostructures can serve as optical couplers across the nano–micro interface. They also have the unique ability to enhance local electromagnetic fields for a number of ultra-compact, subwavelength photonic devices. Nanophotonics is not only about very small photonic circuits and chips, but also about new ways of sculpting the flow of light with nanostructures and nanoparticles exhibiting fascinating optical properties never seen in macro-world. v vi Preface Plasmonic nanostructures utilizing surface plasmons (SPs) have been extensively investigated during the last decade and show a plethora of amazing effects and fascinating phenomena, such as extraordinary light transmission, giant field enhancement, SP nano-guides, and recently emerged metamaterials that are often based on plamonic nanostructures. Nanoplasmonics-based metamaterials are expected to open a new gate- way to unprecedented electromagnetic properties and functionality un- attainable from naturally occurring materials. The structural units of metamaterials can be tailored in shape and size, their composition and morphology can be artificially tuned, and inclusions can be designed and placed at desired locations to achieve new functionality. As the Editors of this volume we are deeply grateful to all contributing authors, leading experts in various areas of nanoplasmoincs, for their effort and their willingness to share recent results within the framework of this volume. Vladimir M. Shalaev and Satoshi Kawata Contents Preface ........................................... v List of Contributors . ............................... xiii Chapter 1. Dynamic components utilizing long-range surface plasmon polaritons, Sergey I. Bozhevolnyi (Aalborg Øst, Denmark) ....... 1 y 1. Introduction . 3 y 2. Fundamentals of long-range surface plasmon polaritons . 5 2.1. Long-range surface plasmon polaritons . ........................ 6 2.2. LRSPP stripe modes . ................................... 10 y 3. Basic waveguide fabrication and characterization . 12 y 4. Interferometric modulators and directional-coupler switches . 16 4.1. Mach-Zehnder interferometric modulators....................... 18 4.2. Directional coupler switches . .............................. 20 y 5. In-line extinction modulators . 21 y 6. Integrated power monitors . 26 6.1. Design considerations . ................................... 26 6.2. Fabrication and characterization.............................. 28 6.3. Sensitivity.............................................. 30 y 7. Outlook . 32 Acknowledgments . 33 References . 33 Chapter 2. Metal strip and wire waveguides for surface plasmon polaritons, J.R. Krenn (Graz, Austria) and J.-C. Weeber, A. Dereux (Dijon, France) . ........................... 35 y 1. Introduction . 37 y 2. Experimental aspects . 38 2.1. Lithographic sample fabrication .............................. 38 2.2. Light/SPP coupling ....................................... 39 2.3. SPP imaging . ......................................... 40 2.3.1. Far-field microscopy . ................................ 40 2.3.2. Near-field microscopy ................................ 41 y 3. Metal strips. 42 3.1. Field distribution of metal strip modes . ........................ 42 3.2. Microstructured metal strips. .............................. 45 3.3. Routing SPPs with integrated Bragg mirrors . ................... 49 y 4. Metal nanowires . 51 4.1. Lithographically fabricated nanowires . ........................ 52 vii viii Contents 4.2. Chemically fabricated nanowires.............................. 55 y 5. Summary and future directions . 58 Acknowledgments . 59 References . 60 Chapter 3. Super-resolution microscopy using surface plasmon polaritons, Igor I. Smolyaninov (College Park, MD) and Anatoly V. Zayats (Belfast, UK) . ....................... 63 y 1. Introduction . 65 y 2. Principles of SPP-assisted microscopy . 70 2.1. Experimental realization of dielectric SPP mirrors ................. 70 2.2. Properties of short-wavelength SPPs . ........................ 72 2.3. Image formation in focusing SPP mirrors ....................... 77 y 3. Imaging through photonic crystal space. 81 y 4. Imaging and resolution tests . 86 y 5. The role of effective refractive index of the SPP crystal mirror in image magnification . 92 y 6. Experimental observation of negative refraction . 97 y 7. SPP microscopy application in biological imaging. 100 y 8. Digital resolution enhancement . 103 y 9. Conclusion . 106 Acknowledgements . 106 References . 106 Chapter 4. Active plasmonics, Alexey V. Krasavin, Kevin F. MacDonald, Nikolay I. Zheludev (Southampton, UK) . ............................... 109 y 1. Introduction . 111 y 2. The concept of active plasmonics . 112 y 3. Coupling light to and from SPP waves with gratings. 114 y 4. Modelling SPP propagation in an active plasmonic device. 123 y 5. Active plasmonics: experimental tests. 131 y 6. Summary and conclusions . 135 Acknowledgements . 137 References . 137 Chapter 5. Surface plasmons and gain media, M.A. Noginov, G. Zhu (Norfolk, VA) and V.P. Drachev, V.M. Shalaev (West Lafayette, IN) . ............................... 141 y 1. Introduction . 143 y 2. Estimation of the critical gain . 148 y 3. Experimental samples and setups . 149 y 4. Experimental results and discussion. 149 4.1. Absorption spectra ....................................... 149 4.2. Spontaneous emission . ................................... 151 4.3. Enhanced Rayleigh scattering due to compensation of loss in metal by gain in dielectric .................................