Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D. (Exhibit 1007)
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`UNITED STATES PATENT AND TRADEMARK OFFICE
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`BEFORE THE PATENT TRIAL AND APPEAL BOARD
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`FUJITSU NETWORK COMMUNICATIONS, INC.
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`Petitioner
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`v.
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`THOMAS SWAN & CO. LTD.
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`Patent Owner
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`Inter Partes Review Case No. Unassigned
`Patent 8,089,683
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`DECLARATION OF TIMOTHY J. DRABIK, Ph.D.
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`(Submitted with Petition for Inter Partes Review of
`U.S. Patent No. 8,089,683)
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`Mail Stop “PATENT BOARD”
`Patent Trial and Appeal Board
`U.S. Patent and Trademark Office
`P.O. Box 1450
`Alexandria, VA 22313-1450
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`FNC 1007
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`I.
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
`TABLE OF CONTENTS
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`INTRODUCTION ........................................................................................... 1
`A.
`Background ........................................................................................... 1
`B.
`Qualifications ........................................................................................ 2
`1.
`Education .................................................................................... 2
`2.
`Career History ............................................................................ 3
`3.
`Publications ................................................................................ 5
`4.
`Other Relevant Qualifications .................................................... 6
`THE ’683 PATENT ........................................................................................ 7
`II.
`III. LIST OF DOCUMENTS CONSIDERED IN FORMULATING MY
`OPINION ........................................................................................................ 8
`IV. TECHNICAL BACKGROUND ................................................................... 11
`V.
`STATE OF THE ART AS OF SEPTEMBER 3, 2001 ................................. 26
`VI. PERSON OF ORDINARY SKILL IN THE ART ........................................ 34
`VII. THE ’683 PATENT SPECIFICATION ........................................................ 35
`VIII. THE CLAIMS OF THE ’683 PATENT ....................................................... 36
`IX. LEGAL STANDARDS ................................................................................. 37
`A. Anticipation ........................................................................................ 37
`B.
`Obviousness ........................................................................................ 38
`CLAIM CONSTRUCTION .......................................................................... 43
`X.
`XI. ANALYSIS OF INVALIDITY GROUNDS ................................................ 45
`A.
`Summary of Analysis ......................................................................... 45
`B.
`Point 1: The Parker Thesis Discloses Every Element of Claim
`18 ......................................................................................................... 49
`Point 2: Claim 18 Is Not Innovative in View of the Parker
`Thesis .................................................................................................. 54
`Point 3: Claims 20, 22, 24, and 25 Are Not Innovative in View
`of the Parker Thesis and the Warr Thesis ........................................... 55
`Point 4: Claims 26 and 27 Are Not Innovative in View of the
`Parker Thesis, the Warr Thesis and Rancuret ..................................... 72
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`C.
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`D.
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`E.
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`F.
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`Point 5: Claim 28 Is Not Innovative in View of the
`Combination of the Parker Thesis, the Warr Thesis and the
`Crossland Patent ................................................................................. 76
`Point 6: Claims 29, 30, 31 and 34 Are Not Innovative in View
`of the Parker Thesis, the Warr Thesis and Crossland ......................... 81
`Point 7: Claims 38 and 39 Are Not Innovative in View of the
`Parker Thesis, the Warr Thesis and Tomlinson .................................. 88
`Point 8: Claims 42-44 Are Not Innovative in View of the Parker
`Thesis, the Warr Thesis and Cohen .................................................... 93
`XII. CONCLUSION ........................................................................................... 101
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`G.
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`H.
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`I.
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`I, Timothy J. Drabik, hereby declare as follows:
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`I.
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`INTRODUCTION
`A. Background
`1. My name is Timothy J. Drabik. I am a researcher and consultant
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`working in areas related to optics, telecommunications, display technologies, and
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`microelectronics. I undertake consulting through my company, Page Mill
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`Technology Corporation, and also work to develop commercial technologies for
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`information display and optical telecommunications.
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`2.
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`I have been retained as an expert witness on behalf of Fujitsu Network
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`Communications, INC. (“FNC”) in connection with the above captioned Petition
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`for Inter Partes Review of U.S. Patent No. 8,089,683 (“Petition”). I understand
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`that this proceeding involves U.S. Patent No. 8,089,683 (“the ’683 patent”), titled
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`“Optical Processing.” The’683 patent is provided as Exhibit 1001.
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`3.
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`I understand that Petitioner challenges in its Petition the validity of
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`Claims 18, 20, 22, 24–31, 34, 38, 39, and 42–44 of the ’683 patent (the
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`“challenged claims”).
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`4.
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`I have reviewed and am familiar with the ’683 patent as well as its
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`prosecution history. The ’683 prosecution history is provided as Exhibit 1002.
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`Additionally, I have reviewed materials identified in Section III.
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`5.
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`As set forth below, I am familiar with the technology at issue as of
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`both the Sep. 10, 2004 filing date of the application which led to the ’683 patent,
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`and the Sep. 3, 2001 priority date corresponding to the filing of the parent UK
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`Patent Application No. 0121308.1. I have been asked to provide my technical
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`review, analysis, insights, and opinions regarding the prior art references that form
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`the basis for the Petition. In forming my opinions, I have relied on my own
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`experience and knowledge, my review of the ’683 patent and its file history, and of
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`the prior art references cited in the Petition.
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`6. My opinions expressed in this Declaration rely to a great extent on my
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`own personal knowledge and recollection. However, to the extent I considered
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`specific documents or data in formulating the opinions expressed in this
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`Declaration, such items are expressly referred to in this Declaration.
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`7.
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`I am being compensated for my time in connection with this IPR at
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`my standard consulting rate, which is $500 per hour.
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`B. Qualifications
`Education
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`1.
`I received my Ph.D. in Electrical Engineering from the Georgia
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`8.
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`Institute of Technology in 1990, where I also received a M.S. degree in Electrical
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`Engineering in 1982. I received Bachelor’s degrees in Electrical Engineering and
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`in Mathematics from Rose-Hulman Institute of Technology in 1981; I also
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`received certification in technical translation of German to English.
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`Career History
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`2.
`I have over thirty years of experience in the areas of optics and optical
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`9.
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`engineering, optoelectronics, telecommunications, liquid crystal display
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`technology, signal and image processing for video applications, microelectronics
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`and integrated circuit design, device packaging, digital systems, and high-
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`performance computing. I have worked both in the academic and industrial
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`environments.
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`10.
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`I held Assistant Professor and Associate Professor appointments at
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`Georgia Tech through the 1990s in electrical and computer engineering, and
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`Visiting and Consulting Professorships at Stanford University from 1999 to 2009.
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`I have taught courses in a broad range of areas, run a research laboratory, and
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`graduated Ph.D. students. I have done research program development with
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`government and industrial entities in the U.S., France, the UK, and other countries.
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`I also have worked for a number of companies. I have been employed directly by
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`AT&T Bell Labs, Displaytech, Inc., Sun Microsystems, and Spectralane, Inc.
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`Among my past consulting clients are the NASA Jet Propulsion Laboratory,
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`Siemens Corporate Research, and early-stage investors performing due diligence
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`prior to making investment decisions.
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`11. At AT&T Bell Labs in the early 1980s, I worked in a department that
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`was developing technologies and services for fiber-to-the home systems. Voice,
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`data, and television content were provided. I designed hardware and also
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`investigated options for video bandwidth compression and coding.
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`12. As a graduate student, I developed technologies for controlling arrays
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`of optical switches integrated with silicon chips. One of these technologies
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`combined ferroelectric liquid crystals (LCs) on silicon integrated circuit chips
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`(LCOS), and formed the basis for the microdisplays I developed later. This
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`technology is central to the patent at issue in this proceeding.
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`13. At Georgia Tech and Stanford, I directed research activity in liquid
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`crystal microdisplay technology, diffractive optics, optoelectronic packaging and
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`hybrid integration, and high-speed interconnection of digital systems, and
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`graduated four Ph.D. students working in these areas. Specifically, I conducted
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`research with Displaytech, Inc., which led to the development of commercial
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`liquid-crystal-on-silicon microdisplays. I developed new manufacturing
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`technology, designed the underlying pixel array and peripheral/driver circuitry for
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`a dozen designs, and tested and evaluated displays. I also taught courses in digital
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`signal processing, Fourier optics and holography, optical information processing,
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`information theory, pattern recognition, semiconductor electronics, integrated
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`circuit design, linear system theory, operational mathematics, and other areas, at
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`the undergraduate and graduate levels.
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`14. As Director of Telecommunications with Displaytech, I developed
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`liquid crystal devices and designed subsystems for transparent optical switching
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`and signal restoration for single-mode, long haul optical transmission. This work
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`entailed development of new optical switch architectures as well as investigation of
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`new liquid crystal component manufacturing technologies to meet the strenuous
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`reliability requirements of the optical telecommunication industry. In particular, I
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`worked in the 2000 time frame to develop optical add/drop multiplexor subsystems
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`based on liquid crystal on silicon (LCOS) technology.
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`Publications
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`3.
`I have published more than 30 articles in scholarly journals, and am
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`15.
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`the first named inventor on four U.S. Patents. I have also delivered invited
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`addresses to the U.S.–Japan Joint Optoelectronics Project Expert Workshop
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`(Makuhari, Japan), the Scottish Optoelectronics Association and Institute of
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`Physics Meeting on Optical Interconnections for Information Processing
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`(Edinburgh, Scotland), the Annual Meeting of the Materials Research Society (San
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`Francisco, CA), and the IEEE/LEOS Workshop on Interconnections within High-
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`Speed Digital Systems (Santa Fe, NM). I have served the European Union as an
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`Expert Reviewer for EU research programs in microelectronics and optics, and the
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`National Science Foundation as a reviewer of research proposals.
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`Other Relevant Qualifications
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`4.
`16. My consulting practice has involved the design of optoelectronic
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`integrated systems on custom silicon platforms, development of new liquid crystal
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`cell technology and manufacturing technology, investigation of advanced
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`processor–memory architectures for high-performance parallel computing, and
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`development of long-haul optical fiber transmission subsystems. Specifically, for
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`Spectralane, Inc., a Silicon Valley startup pursuing disruptive techniques for
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`ameliorating nonlinear impairments in long-haul, wavelength-division-multiplexed
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`fiber systems, I developed simulation and modeling tools to aid in subsystem
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`design, used those tools to develop effective subsystem architectures, and drafted
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`patents.
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`17. My practice also has involved preparing U.S. Patent applications,
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`providing patent infringement and validity studies and reports, and conducting
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`intellectual property due diligence investigations in connection with venture
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`financing. I have previously served as an expert in litigation matters relating to
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`(among other areas) optical switching, optical fiber transmitter and receiver
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`components, video processing technologies, the design, fabrication, and operation
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`of liquid crystal displays, and optical disk drive technologies.
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`18. My curriculum vitae, Exhibit 1014, includes a compilation of my
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`publications and patents, lists litigation matters in which I have been engaged, and,
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`in particular, includes those in which I have provided testimony over the previous
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`four years.
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`II. THE ’683 PATENT
`19. The above-referenced IPR petition seeks review of U.S. Patent No.
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`8,089,683 (“the ’683 patent”), Ex. 1001. The ’683 patent is among a number of
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`patents that ultimately claims priority to UK Patent Application No. 0121308.1,
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`filed on September 3, 2001. The chain is as follows: PCT Application No.
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`PCT/GB02/04011 was filed on September 2, 2002. U.S. national stage Patent
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`Application No. 10/487,810 was filed on September 10, 2004. Divisional U.S.
`
`Application No. 11/515,389 is now U.S. Patent No. 7,612,930), was filed on
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`September 1, 2006. U.S. continuation Patent Application No. 11/978,258, was
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`filed October 29, 2007, and led to the issuance of the ’683 patent. I understand that
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`the ’683 patent is currently assigned to Thomas Swan & Co. Ltd. (“Swan”).
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`20. The technology related to the claims of the ‘683 patent has
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`applications in fiber optic communications as, for example, switches, filters, and
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`attenuators.
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`21. Melanie Holmes (“Holmes”) is listed as the sole inventor for the ‘683
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`patent and the priority application.
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`III. LIST OF DOCUMENTS CONSIDERED IN FORMULATING MY
`OPINION
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`22.
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`In formulating my opinion, I have considered all of the following
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`documents:
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`Description
`
`Exhibit
`Ex. 1001 U.S. Patent No. 8,089,683
`Ex. 1002 Biography of Prof. Crossland, http://www-
`g.eng.cam.ac.uk/photonics_sensors/people/bill-
`crossland.htm
`Ex. 1003 Listing of Publications from Photonics & Sensors group,
`http://www-
`g.eng.cam.ac.uk/photonics_sensors/publications/index.htm
`Ex. 1004 M. J. Holmes et al., “Low Crosstalk Devices for Wavelength-
`Routed Networks,” in Tech. Dig. IEE Colloquium, pp. 2/1-2/10, June 8,
`1995.
`Ex. 1005 W.A. Crossland et al., “Holographic Optical Switching: The ‘ROSES’
`Demonstrator,” Journal of Lightwave Technology, Vol. 18, No. 12,
`pp. 1845-1854, December 2000.
`Ex. 1006 Memorandum Opinion and Order, Thomas Swan & Co. Ltd. v.
`Finisar Corp. & Fujitsu Network Communications, Inc., No.
`2:13-cv-178 (E.D. Texas), Dkt. 157 (June 25, 2014)
`Ex. 1008 Michael Charles Parker, Dynamic Holograms for Wavelength Division
`Multiplexing, Thesis at University of Cambridge, November 1996
`(“Parker Thesis”)
`Ex. 1009 Stephen Thomas Warr, Free Space Switching for Optical Fibre
`Networks, Thesis at University of Cambridge, July 1996 (“Warr
`Thesis”)
`Ex. 1010 U.S. Patent No. 6,958,841 to Rancuret et al. (“Rancuret”)
`Ex. 1011 U.S. Patent Application Publication No. 2001/0050787 (“Crossland
`Patent”)
`Ex. 1012 U.S. Patent No. 6,549,865 to Tomlinson (“Tomlinson”)
`
`Ex. 1013 A.D. Cohen et al., “100-GHz-Resolution Dynamic Holographic
`Channel Management for WDM,” IEEE Photonics Technology Letters,
`Vol. 11, No. 7, pp. 851-853, July 1999 (“Cohen”)
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`Ex. 1014 Curriculum Vitae of Dr. Timothy J. Drabik
`Ex. 1015 Declaration of Louise Clarke of Cambridge University, August 18,
`2014
`Ex. 1016 Timothy J. Drabik, “Optoelectronic Integrated Systems Based on Free-
`Space Interconnects with an Arbitrary Degree of Space Variance,”
`Proceedings of the IEEE, Vol. 82, No. 11, pp. 1595-1622 November
`1994.
`Ex. 1017 File History of U.S. Patent No. 8,089,683
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`Ex. 1018 File History of U.S. Patent No. 7,145,710
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`Ex. 1019 Timothy J. Drabik et al., “2D Silicon/Ferroelectric Liquid Crystal
`Spatial Light Modulators,” IEEE Micro, Vol. 15, No. 4, pp. 67–76,
`August 1995.
`Ex. 1020 Joseph E. Ford, “Wavelength Add-Drop Switching Using Tilting
`Micromirrors,” Journal of Lightwave Technology, Vol. 17, No. 5, pp.
`904–911, May 1999.
`Ex. 1021 Joseph W. Goodman, Introduction to Fourier Optics, Second Edition,
`McGraw-Hill (1996).
`
`Ex. 1022 U.S. Patent No. 5,552,916 to O’Callaghan et al.
`
`Ex. 1023 Hirofumi Yamazaki, “Experiments on a multichannel holographic
`optical switch with the use of a liquid-crystal display,” Optics Letters,
`Vol. 17, No. 17, pp. 1228–1230, Sept. 1, 1992.
`Ex. 1024 L. K. Cotter et al., “Ferroelectric-liquid-crystal/silicon-integrated-
`circuit spatial light modulator,” Optics Letters, Vol. 15, No. 5, pp. 291–
`293, March 1, 1990.
`Ex. 1025 J.E. Fouquet et al, “A Compact Scalable Cross-Connect Switch Using
`Total Internal Reflection Due to Thermally-Generated Bubbles,” in
`Tech. Dig. IEEE LEOS Annual Meeting, Orlando, FL, 1998, pp. 169–
`170.
`Ex. 1026 A. Husain, “MEMS-Based Photonic Switching in Communications
`Networks,”in Tech. Dig. OSA Conference on Optical Fiber
`Communication, 2001, pp. WX1-1–WX1-3.
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`Ex. 1027 H. Laor, “Construction and performance of a 576×576 single-stage
`OXC,” in Tech. Dig. LEOS ’99 (vol. 2), Nov. 8–11, 1999, pp. 481–482.
`
`Ex. 1028 S.-S. Lee, “Surface-Micromachined Free-Space Fiber Optic Switches
`With Integrated Microactuators for Optical Fiber Communications
`Systems,” in Tech. Dig. 1997 International Conference on Solid-State
`Sensors and Actuators, Chicago, June 16-19, 1997, pp. 85–88.
`Ex. 1029 L.Y. Lin, “Free-Space Micromachined Optical Switches for Optical
`Networking, IEEE Journal of Selected Topics In Quantum
`Electronics,” Vol. 5, No. 1, pp. 4–9, Jan./Feb. 1999.
`Ex. 1030 Mitsuhiro Makihara et al., “Strictly Non-blocking NxN Thermo-
`Capillarity Optical Matrix Switch using Silica-based Waveguide,” in
`Tech. Dig. OSA Conference on Optical Fiber Communication, 2000,
`pp. TuM2-1–TuM2-4.
`Ex. 1031 R. Ryf, “1296-port MEMS Transparent Optical Crossconnect with 2.07
`Petabit/s Switch Capacity,” in Tech. Dig. OSA Conference on Optical
`Fiber Communication, March 2001, pp. PD28-1–PD28-3.
`Ex. 1032 G. Tricoles, “Computer generated holograms: an historical review,”
`Applied Optics, Vol. 26, No. 20, pp. 4351–4360, Oct. 15, 1987.
`
`Ex. 1033 Jorgen Bengtsson, “Design of fan-out kinoforms in the entire scalar
`diffraction regime with an optical-rotation-angle method,” Applied
`Optics, Vol. 36, No. 32, pp. 8435–8444, Nov. 10, 1997.
`Ex. 1034 Jun Amako et al., “Kinoform using an electrically controlled
`birefringent liquid-crystal spatial light modulator,” Applied Optics, Vol.
`30, No. 32, pp. 4622–4628, Nov. 10, 1991.
`Ex. 1035 U.S. Provisional Patent App. No. 60/293126 to Rancuret et al.
`(“Rancuret Provisional”)
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`23.
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`I have reviewed the substance of the Petition for Inter Partes Review
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`that will be submitted with this Declaration (and I agree with the technical analysis
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`that underlies the positions set forth in the Petition).
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`IV. TECHNICAL BACKGROUND
`A. Optical switching for telecommunications
`Fiber cross-connects
`1.
`24. Optical fiber network systems most preferably have a flexible
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`capability of provisioning so that bandwidth may be reconfigured to accommodate
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`changes in demand or to recover from faults.
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`25. At the coarsest level of network provisioning, links originating at
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`various geographic locations and entering a service facility may be selectively
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`interconnected with each other to allocate entire fiber paths to link locations. A
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`traditional way to implement this function is by means of a patch panel, an
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`example of which is pictured below, whereby fibers from various geographic
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`locations may be connected by installing short patch cables manually.
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`If such changes are frequent, however, the cost and delay of “truck rolls” to bring
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`technicians to service facilities may become onerous. Therefore, an automated
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`means for whole-fiber provisioning is desirable.
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`26. The graphic below shows a possible arrangement for what is called a
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`space-division switch, or space switch, using arrays of computer-controlled
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`mirrors, that implements the same function as a patch panel.1
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`27. Such a switch may be referred to as an optical cross-connect (OXC).
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`In operation, the optical signal from an input fiber is collimated by means of a lens
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`and continues in the form of a pencil-like beam to a dedicated mirror in a first
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`array. The mirror tilt is adjusted to point the reflected beam at the mirror
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`corresponding to the desired output fiber. The second mirror is adjusted to point
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`its reflected beam so that it couples into the output fiber through its collimator.
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`Because the mirrors are under computer control, no trucks need roll, and network
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`operational costs can be reduced.
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`1 It is desirable for a switch to be bidirectional, i.e., for signals to be routed reliably
`from “outputs” to “inputs” as well as from “inputs” to “outputs.” This can
`generally be achieved with suitable engineering.
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`2. Wavelength switches
`28. The granularity of such provisioning is coarse—a single fiber may
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`carry multiple terabits per second (Tb/s) in each direction—and it is desirable to be
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`able to allocate smaller chunks of bandwidth among fibers.
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`29.
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` Wavelength-division multiplexing (WDM) is used to impress multiple
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`Tb/s of information onto a single fiber. This is done by dividing the spectrum of
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`light into wavelength channels, each of which is capable of carrying discrete
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`information. Because power in different channels does not overlap in wavelength,
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`a single channel or set of channels may be split off—demultiplexed— from a fiber
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`by means of filtering. Many optical techniques for wavelength selectivity have
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`been employed for wavelength multiplexing and demultiplexing. Gratings capable
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`of dispersing light by wavelength have been used in this regard to create devices
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`that can add (or drop) wavelengths or groups of wavelengths to (or from) a fiber.
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`If individual wavelength channels can be reallocated among fibers, provisioning
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`can be effected with a granularity of tens of Gb/s.
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`30. Prior to the alleged invention, it was known to implement wavelength
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`control in a space switch to effect wavelength provisioning in a remotely
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`controllable fashion. This can be done by using space switches in conjunction with
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`wavelength multiplexers and demultiplexers. In the exemplary system shown in
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`the graphic below, for example, a demux element places each wavelength channel
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`from a WDM input port onto a distinct optical path. Then, space switches are used
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`to send each wavelength to a desired destination port. Multiple wavelengths
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`intended for a destination port are combined by a mux element. Multiplexing and
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`switching functions can be implemented in various ways.
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`Free-space optical systems
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`B.
`31. The art discussed in this Declaration employs optical architectures
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`based at least in part on free-space propagation, i.e., propagation that is not
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`confined to a fiber or other kind of waveguide. It is useful to understand the
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`principles by which such systems function.
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`1.
`32. Focusing elements such as lenses and concave mirrors were known
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`Basic properties of lenses
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`components of free-space optical systems. They groom light emerging from fibers,
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`and they also operate on image fields bearing many independent channels of light.
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`33. The illustration below highlights certain properties of ideal lenses that
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`are exploited in free-space systems. At left is a ray optics picture of propagating
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`beams. An ideal lens is characterized by its focal distance f.
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`Rays originating at a focal point (a distance f from the lens center along its axis)
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`are transformed to horizontal rays on the other side of the lens. But also, rays
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`originating at a common point anywhere in a focal plane all are transformed to
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`parallel rays on the other side of the lens. The rays’ common direction may be
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`found by tracing the ray passing through the lens center, which is not deflected.
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`Note that there are no arrows in the ray diagrams to indicate propagation direction:
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`because of the principle of reciprocity, the ray diagrams may be interpreted either
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`for light traveling generally left-to-right or right-to-left. Thus, rays arriving in a
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`common direction also are transformed to pass through the focal plane at a
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`common point. These basic phenomena underlie the imaging properties of lenses.2
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`2 Single-lens imaging is often depicted as illustrated below, according to the
`equation 1/S1 + 1/S2 = 1/f:
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`15
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`34. The image at right in the illustration above shows qualitatively how
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`beams having lateral extent are transformed by lenses. A collimated beam (one
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`having flat wavefronts) many wavelengths in diameter remains substantially
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`collimated until the lens transforms it into a converging beam that attains its
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`minimum spot size in the focal plane, which size may be of the order of a few
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`wavelengths. Reciprocally, a diverging beam emerging, e.g., from a cleaved,
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`single-mode fiber end in the focal plane, is collimated by the lens. Note that the
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`paths of the extended beams’ central axes are the same as in the simple ray picture
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`of lens behavior.3
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`2.
`35. The designation “Fourier lens” or “Fourier transform lens” commonly
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`The “Fourier lens”
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`has been used in the art to refer to lenses that convey multiple information beams
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`within a system. This designation arises from a deep correspondence between lens
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`phenomenology and the theory of Fourier signal analysis.4
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`
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`3 The colors in the above diagram are provided for illustration only, and are not
`meant to convey wavelength information. The focal distance of actual physical
`lenses may vary non-negligibly with wavelength.
`4 This correspondence is elucidated in Ex. 1021.
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`36. One characterization of lenses is that they transform angles to
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`displacements and displacements to angles. This behavior can be observed in the
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`above ray-optics illustration of light propagating between the focal planes of a lens.
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`The Fourier transform, in turn, transforms functions based on temporal or spatial
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`coordinates, to functions based on temporal or spatial frequency, which represent
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`the same information as the original functions. Spatial frequency is approximately
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`proportional to the beam’s angle to the axis, for small angles. Thus a lens may be
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`thought of as transforming a spatial coordinate (beam displacement from the lens
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`axis) to spatial frequency (beam angle with respect to the lens axis) and vice versa.
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`The correspondence admits the use of Fourier signal analysis for the design and
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`analysis of optical systems.
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`3. Wavelength-dispersive elements
`37. As noted above, it was known to employ dispersive elements such as
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`gratings in free-space systems to separate individual wavelength channels from a
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`WDM signal, so that they can be treated independently. The graphic below shows
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`both a prism and a grating that perform this function:
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`17
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`38. The prism deflects light because the thin end imposes a smaller delay
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`on a light wave passing through it than the thick end. But also, in terms of
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`oscillation periods of the optical field, a given time delay represents more cycles of
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`short-wavelength (e.g., blue) light than of long-wavelength (red) light. Thus, a
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`prism deflects shorter wavelengths more than longer wavelengths.
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`39. A grating disperses light by diffraction. The illustration below depicts
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`an amplitude grating in cross-section because it presumptively affects amplitude.
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`The grating can be thought of as an opaque sheet with narrow, parallel slits cut into
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`it at equal intervals. The wave emerging from each narrow slit diverges
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`substantially. Zero-phase contours of the incident and diffracted waves are shown
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`as blue lines. Thus, there is more than one direction in which the “wavelets” will
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`18
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`interfere constructively to form a diffracted wave, each referred to as an “order”.5
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`The angle θ through which normally incident light is diffracted into the first order
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`(the least angle of deflection)6 is approximately the ratio of the optical wavelength
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`λ to the grating pitch Λ (θ ≈ λ/Λ), so that a finer-pitch grating will deflect a given
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`beam through a larger angle.
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`40. The relative strength of the various diffracted orders depends on the
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`nature of the grating. The graphic below illustrates schematically how differently
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`fabricated transmissive, diffractive optical elements (DOEs) sharing a common
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`grating period, may generate diffracted light. Such elements may typically be
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`created on glass or fused quartz substrates by means of lithographic patterning and
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`etching processes, for example. In such gratings, the diffraction angle may be
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`5 This construction is due to Huygens and was developed further by Young and
`Fresnel in the early 19th Century. See, e.g., Ex. 1021 at 33–35.
`6 The wavefront corresponding to the first diffracted order is the envelope formed
`when adjacent wavelets are considered that have a relative phase difference of 2π,
`i.e., of a single, full wave. If adjacent wavelets are considered that have a relative
`delay of two waves, constructive interference may occur to form the second
`diffracted order.
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`19
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`affected by the depth of a groove and/or the refractive index of the material. In
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`Inter Partes Review of USPN 8,089,683
`Declaration of Timothy J. Drabik, Ph.D.
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`principle, a “continuous-phase DOE” can route all incident light power into the
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`(desired) first diffracted order. However, a continuous-phase element may be
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`difficult or expensive to produce. An amplitude DOE sends power into a number
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`of higher diffracted orders, and absorbs incident light as well.
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`
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`41. A continuous-phase grating having a small grating period (of the order
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`of an optical wavelength) and designed to direct the maximum amount of power
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`into a single order, may be used to spread the relatively closely-spaced wavelength
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`channels of dense WDM signals over a suitable angle. It was known that such
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`gratings may also be coated to operate in reflection to suit a specific system
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`architecture.
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`42. Prior to the alleged