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This edition first published 2010

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Library of Congress Cataloging-in-Publication Data

Holographic data storage : from theory to practical systems / Kevin Curtis . . . [et al.].

p. cm.

Includes bibliographical references and index.

ISBN 978-0-470-74962-3 (cloth : alk. paper)

1. Holographic storage devices (Computer science) I. Curtis, Kevin R.

TA1632.H6635 2010

004.5#x2032;65–dc22

2010008437

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

ISBN: HB: 9780470749623

Foreword

The modern field of nonvolatile digital information storage is a bit more than a half-century old. During its history, the field has seen a small handful of technologies (magnetic tape, magnetic hard disk, magnetic flexible disk, consumer-derived optical disk) take root as ‘mainstream’. These technologies have persisted in the market place from their earliest introduction until today, experiencing commercial success for several decades or longer. A few other digital storage technologies have emerged and been successfully commercialized in less broad based applications (e.g. magnetic drums, optical cards, magneto-optical disk) and, typically, their success has been of shorter duration. A third, quite numerous, category of storage technologies involves new approaches that have not yet achieved commercial success. The subject of this book, holographic data storage, is in this third category.

Among the many examples of promising storage technologies that have been worked on over the past 50 years, holographic storage offers a unique combination of desirable attributes: extremely high density of stored information, a disk format capable of rapid random access, and a removable nonvolatile storage medium that may be inexpensively manufactured. While these attributes are simple to discuss in general, putting them all together in a practical and reliable storage system represents a herculean engineering task. This is exactly what InPhase Technologies has accomplished, and what the company's contributors describe in detail in this book.

As the authors point out in the Introduction, with other optical storage technologies facing obstacles to significant performance improvements, interest in holographic data storage has dramatically increased in recent years. Although the increased interest is recent, the history of research and development in holographic storage extends back nearly 50 years, with contributions from many universities, government- and industry-sponsored consortia, and industrial companies. The uniqueness of the InPhase contribution is that they have progressed far beyond the basic research aspects of holographic storage and have persevered to address the multitude of materials, optical, mechanical and electrical engineering challenges necessary to develop a fully integrated drive-media storage system.

This book takes the reader through many details of the technical challenges encountered along this development path and of the often creative design solutions implemented to meet those challenges. Undoubtedly, the complexities of implementing a fully practical commercial system proved greater than anticipated by the InPhase team at the outset, but that is a natural occurrence when attempting to break new ground and introduce a new technology that represents so significant a departure from the incumbent approaches. To the team's credit, their approach over the years has been very open and forthcoming in describing the difficult challenges in their technical conference and journal papers. The team continues that practice in the detailed chapters of this book. Because of this openness, the book can serve as an excellent reference to developers of future holographic data storage systems and enable them to build upon and improve the technology.

From an applications perspective, the book focuses on professional archival storage, with some treatment of devices for consumer applications. Professional archival storage is a domain currently dominated by magnetic tape, and the tape technology community continues to aggressively advance its technology, following a roadmap that doubles storage capacity every 2 years. This competitive environment poses an additional challenge for InPhase, beyond the strictly technical challenges noted above.

At the same time, the demand for archival storage capacity is growing at a rapid rate, as the world continues to generate an exploding quantity of digital information. Much of this information is ‘fixed content’ and needs to be reliably retained for a decade or longer. As one measure of the enormous amount of digital information generated, a recently published study reports that in 2008 Americans consumed more than 3.6 zettabytes of information (1 zettabyte = 10²¹ bytes). Although the study emphasizes information ‘flow’ rather than information ‘storage’, it is clear that a significant fraction of the information described is stored in professional archival repositories.

This growing requirement for archival data retention presents an attractive opportunity for holographic data storage. The InPhase professional storage system with removable disk media is the first ever commercial holographic product to be introduced for such applications. It is indeed a pioneering development. While time will tell if the product becomes a commercial success, this book renders a wonderfully detailed and descriptive technical account of the path taken to reach this milestone.

Barry H. Schechtman

Executive Director Emeritus

Information Storage Industry Consortium (INSIC)

R.E. Bohn and J.E. Short, How much information?, 2009 Report on American Consumers, Global Information Industry Center, University of California, San Diego, 2009; http://hmi.ucsd.edu/pdf/HMI_2009_ConsumerReport_Dec9_2009.pdf

Preface

This book is a result of over 15 years of research and development in holographic data storage, first at AT&T (then Lucent) Bell Laboratories and then at InPhase Technologies. The book's release is timed to roughly coincide with the release of the first ever commercial product using this technology: a professional archive storage drive using removable disk media. While major developments in holographic data storage outside of this effort are described, the focus is on explaining the design, components, and function of the technology used in InPhase's professional drive and two related consumer data storage products.

This book will enable end users of the technology to understand how the drive and media works, and how they are tested. Our hope is that other developers of holographic storage products can use this book as a basic blueprint for developing their own products using this technology.

A wide range of topics from polymer chemistry to error correction codes are covered in this book. The chapters are in large part independent, with a separate list of references at the end of each one. Although each chapter may refer to other chapters for additional detail, there is no assumption that later chapters require a detailed knowledge of earlier ones.

The first five chapters discuss the commercial market for holographic storage, and provide a broad overview of the drive and media technology. Chapters 6–8 discuss the media in greater depth. The technology underpinning the professional drive is considered in detail in Chapters 9–14. Chapter 15 covers read only memories and high speed replication of holographic media; topics that are central to the development of a consumer market for holographic storage. Finally, Chapter 16 concludes with a discussion of the future evolution of the technology and market applications.

A storage product is an amazingly complex device. As a simple example, the firmware controlling the InPhase drive is approximately 1.5 million lines of custom C++ code, which does not include almost another 1.5 million lines of other C and C++ code comprising the drive's operating systems.

The sum total of significant breakthroughs in media, material, control, optics, mechanics, data channel, and testing in the last 15 years is immense. As such, this book represents the work of over 200 people from different companies at various times.

InPhase Technologies was spun out of Bell Laboratories after 6½ years of fundamental research and development. The support of management and wonderful people at Bell Laboratories enabled the start of this long and improbable journey. We sincerely thank these companies and our collaborators, and acknowledge their many contributions to this work.

We have also had significant interaction with, and help from, Hitachi Maxell, Nichia, Alps Electric, Bayer Material Science, Sanyo, Lite-on, IBM, Datarius, and Sony.

This book is dedicated to the employees, investors, and supporters of InPhase Technologies for their amazing contributions and hard work. This book truly is a result of their labor of love. Above all, we acknowledge and thank our families for their patience, understanding, and support over all these years.

Kevin Curtis

Lisa Dhar

William Wilson

Adrian Hill

Mark Ayres

List of Contributors