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Toshihiko Baba

Short summary of my talk:
Photonic nanostructures, i.e. photonic crystals (PCs) and high index contrast structures (HICs), have attracted attention in this decade. They strongly control light emission and propagation, and so allow novel phenomena and applications. Recently, they are particularly discussed with other topics such as nanolaser, slow light, negative refraction, and Si photonics. My presentation reviewed our research activities on these topics.
The PC nanolaser has been expected as a high-efficiency and high-speed light source in a photonic chip. Two key issues are the small modal volume and high Q. We employed a point-shift nanocavity consisting of only the shift of two neighboring holes in a PC slab. Its cavity mode has an extremely small volume of 0.2 times the cubic wavelength, which is close to the optical diffraction limit. We fabricated it into 1.55-mm-GaInAsP QW slab and obtained the room temperature cw lasing by photopumping with an effective threshold power of nearly 1 micro-watts. For this cavity, we also observed the spontaneous emission enhancement due to the Purcell effect and the nearly thresholdless operation. In the photonic chip, such nanolasers must be integrated with passive components. We integrated them with 1.30-mm-GaInAsP passive PC waveguides using MOVPE buttjoint regrowth process, and obtained a practical value of external quantum efficiency of 8%.
Slow light in the PC waveguide is of great interest due to its potential for optical buffering and enhancement of the light-matter interaction. However, a narrow bandwidth and large group velocity dispersion are serious problems that disturb its practical use. We have proposed some modified PC waveguides for wideband and dispersion-free operation. For example, dispersion-compensated slow light with a group index (= slowdown factor) of 35 - 40 in a wide wavelength range of 35 nm was obtained a directional coupler of chirped PC waveguides with opposite dispersions. The zero-dispersion slowlight was also demonstrated by some minute control of waveguide structure.
Negative refractive optics has become a hot topic with metamaterials. However, those based on PCs are advantageous for lightwaves as they are free from absorption loss. We successfully observed superprism and superlens effects of negative refractive optics in a SOI PC slab by optimizing I/O interfaces for low reflection and diffraction losses. The superlens is unique because it focuses light at the flat surface, and forms a real image inside the PC. This means that the focusing characteristics are independent of the input position of light. A compact wavelength demultiplexer and parallel optical coupler were demonstrated as applications of this lens.
In parallel with PCs, the Si photonics is increasing importance for intra-chip optical interconnects and low-cost and compact photonic lightwave circuits. The HIC Si wire waveguide allows sharp bends and micro-optic components due to the strong optical confinement. In addition to these components, we have demonstrated a very compact H-tree optical signal distribution circuit and AWG demultiplexer whose footprint was less than 100 micron square. By carefully optimizing the connection between elements, the sidelobe level and device loss were reduced to less than -20 dB and 1.5 dB, respectively, and the polarization-insensitive characteristics were also obtained. It will be a practical device for course WDM.

Short summary of my travel:
I visited all the LEOS chapters that invited me, as long as their meeting plan fit to my schedule. The following summarizes the date, chapter, city, place of meeting, organizer of meeting, special note of my trips.
(1) 08/09/06, Japan, Tokyo, Kozai Kaikan, Y. Yoshikuni, I started my year term from Japan with other two DL lecturers Prof. M. Selim Ünlü and Dr. M. Notomi.
(2) 13/10/06, Ottawa, Ottawa, National Research Council, K. Liu, It was just after OSA annual meeting at Rochester. The audience showed particular interest on Si photonics.
(3) 08/11/06, Ukraine, Guanajuato (Mexico), Guanajuato University, I. Sukhoivanov, My talk was scheduled as a formal opening lecture of Multiconference on Electronics and Photonics.
(4) 13/11/06, Italy, Turin, Avago Technology, T. Tambosso, I was impressed by the steadiness of their research on semiconductor devices, while surprised at hearing the low percentage of students in the science and engineering majors in Italy.
(5) 15/11/06, Italy, Rome, Universitate degli Studi di Roma, A. d’Alessandro, I gave a lecture in a special class of the university.
(6) 15/03/07, Poland, Lodz, Technical Institute of Lodz, W. Nakwaski, I also met Prof. M. Marciniak who invited me to International Conference on Transparent Optical Network on June.
(7) 19/03/07, Hampton Roads, Norfork, Old Dominion University, A. Dharamsi, I gave a lecture for undergraduate and younger graduate students of the university.
(8) 20/03/07, Washington/Northern VA, Washington DC., University of Merryland, M. Dagenais, I enjoyed seeing some research activities on bio-sensing and cavity QED of the University.
(9) 21/03/07, Rochester, Corning, Corning Research Center, S. Garner, I saw the history of Corning and recent research on bio-sensing applications.
(10) 14/05/07, Albuquerque, Albuquerque, University of New Mexico, Y. D. Sharma, An image sensor in the wavelength range from 3 to 10 microns and auto-tracking system of laser beam were demonstrated at the visit.
(11) 16/05/07, Central New England, Boston, Boston University, M. Cabodi, A one day symposium on nanophotonics was held, and I and Dr. M. Notomi gave lectures.

 


 

Bishnu P. Pal

In continuation of my report as a Distinguished Lecturer for 2005-06 published in June 2006 issue, I have great pleasure in reporting my experience of participation in this great program during my extended term as DL for 2006-07. During the summer months of June-July, we are entitled to ask for vacation leave of 60 days at my Institute, namely Indian Institute of Technology Delhi. Our Institute Administration is very generous in approving such a request unless there is any compelling administrative reason for denying so. Dr. Lucy Zheng and Dr. George Simonis of the Washington/Northern VA LEOS chapter organized the first talk on June 5th 2006 at the College Park campus of University of Maryland. It was organized as an evening seminar. The attendance was rather thin, as the campus students had already finished their semester end examinations by then and left the campus. Nevertheless there were interesting questions and discussions during the talk, which was attended by attendees from companies like Ciena. Post-talk, my hosts treated Nilotpol Kundagrami, a former student of mine (now working with an American Company in Maryland) and me to a sumptuous dinner at a Korean restaurant near the campus. This visit to the campus also gave me an opportunity to interact with two of College Park campuses well-known researchers namely, Professors Rajarshi Roy and Chris Davis. They were kind enough to give their time for discussing their work and I’m thankful to Chris for showing his laboratories to Nilotpol and I. My next stop was at Norfolk, VA for the Hampton Roads chapter, which was organized by the chapter chair Prof. Amin Dharamsi. Amin is an extremely jovial person, who can make you laugh all the time! Besides giving me a nice tour of different laboratories, he organized the talk at the campus of Old Dominion University, which was attended mostly by students of that university. They raised several questions and queries, which were very interesting for me. I met one of our former students Amir from IIT Delhi, who is currently a Graduate student with Amin; Amir and another fresh Graduate student Karan continued their queries during the dinner at a Thai restaurant. Dr. Sean Garner of Corning Inc. organized the next DL on the evening of June 8th at Sullivan Park campus of Corning Inc. for the Rochester LEOS chapter. It was my close friend Prof. Govind Agrawal (Govind and I were graduate students at IIT Delhi about 30 years ago) of Inst. of Optics, who motivated me to accept this invitation. It allowed me a wonderful opportunity to visit some of Corning’s fiber optics related research laboratories and also to interact with some of its outstanding researchers during the day beginning post-lunch. Sean arranged to video record the lecture for Corning’s technical library, which was indeed an honor. He took pains to publicize the talk announcement for local residents, who could have been interested to listen to the talk as a public lecture. I had explicitly chosen this invitation to get an opportunity to deliver the talk at a famous industry like Corning in Fiber Optics and propagate research interest of academics like us on exotic fibers like microstructured fibers, which happened to be an area of some substantial interest to Corning itself. I have had some follow-up interactions with Dr. Karl Koch of the company, who is involved with R & D on photonic bandgap fibers there. The next stop was at CREOL at University of Central Florida, where my invitation came from the LEOS student chapter. The chapter chair Dr. Yung-Hsun Wu coordinated it with a great deal of enthusiasm and interest. Ozharar Sarper, the new student chapter chair received me on arrival. The number of attendees was very large and I received some very nice compliments from the audience. Dr. Wu also arranged visits to a few of the laboratories, which were of great interest to me. Meeting Professors Peter Delfyett and B. Zeldovich was a bonus; I met Peter first at the Korean Optical Society’s annual meeting early in the year 2006, where he was the second plenary speaker besides me. The excitement with which Prof. Zeldovich demonstrated some of his experiments, which he has devised to explain the fundamental concepts underlying basic physical phenomena such as coupled pendulums for example, through optics, were unique, highly motivating and fascinating. His words of appreciation (e.g. I do not have the words to describe my fascination by the breadth of your fiber work…..) through an email later were very motivating and inspiring. Dr. Wu and her husband (also a Graduate student there at CLEO) made sure that I catch my return flight by driving me to the airport in their own car. It was indeed fascinating to meet several outstanding students at CREOL. Some of the work on Liquid crystal displays was also very interesting. The following week I drove from Rochester, NY (where I stayed for a couple of months with my daughter Parama, who is a Graduate student at the Institute of Optics there with Prof. Wayne Knox) to Ottawa’s NRC for my next talk. The invitation was kindly extended to me by local LEOS chapter Chair Dr. Kexing Liu 9of Ciena), who was helped by Dr. John Alcock of NRC Ottawa in organizing my talk on the afternoon of June 22nd at NRC. I had indicated my interest to John beforehand to visit some of the Photonics related laboratories at NRC, which he had kindly agreed. In particular I was impressed by the laboratory and infrastructure on active semiconductor fabrication during my visit to these laboratories. I had very absorbing discussions with Kexing later on that day over dinner. Finally, I visited the Toronto’s LEOS chapter on June 29th. Dr. Emanuel Istrate, the chapter Chair organized the lecture on the afternoon of that day, which was well attended. I could also meet one of our former students from IIT Delhi there. Before the lecture I had a quick run through some of the very interesting laboratories on various aspects of Photonics, which included work on photonic crystal structures. Emanuel even spent time post-lecture to show me his own work. Emanuel and his Chapter’s Treasurer Dr. Jianzhao Li continued discussions during the dinner. I was very impressed with their depth of knowledge. That summarizes my visits to different LEOS chapters in North America. In 2007, as I have had difficulty getting leave of absence until this summer, I had to regretfully decline several other LEOS chapter requests to visit them. In the meanwhile I was invited by Erasmus Mundas Foundation of European Community to spend some time at the Heriot Watt University in Edinburgh, Scotland as a Photonics Scholar. I reached here at Edinburgh on May 29th. On the way I delivered one of my last DLs at the Technical University of Eindhoven, Netherlands at the invitation of Dr. Fouad Karouta, who had actually invited me to deliver my DL at the Annual Workshop of the Benelux Student chapter held there on May 25th. This year the theme of the workshop was “Progress in Optical Devices and Materials”. I was delighted to get this invitation, as I always look forward to meeting young students all over the world. It was once again a very interesting experience filled with interactions with attendees from several Benelux countries. The workshop was held for the whole day and I stayed on listening to the students’ presentations. One interesting feature of this annual LEOS workshop is that the chapter decides to invite a Ph.D. student, who would have made significant research contributions during his Graduate work. This year Dr. Guenther Roelkens from Ghent University presented this invited talk. Thereafter, I delivered my last DL at City University London on June 26th. Prof. B.M.A. Rahman of City U organized the lecture under the auspices of IEEE MTT/ED/AP/LEOS joint chapter in the form of a half-day seminar addressed by Prof. Brian Culshaw of University of Strathclyde (on possible optical fibers sensors based on Photonic crystal fibers) and Prof. David Richardson from University of Southampton (on high power fiber lasers) besides me. A large number of listeners from other Institutes and laboratories from London formed the audience. This has been my last official DL talk. However I have another DL talk to deliver for the Scottish chapter of LEOS at the behest of Dr. Ajoy Kar, its chair, who insisted that I deliver a talk at their half-day LEOS chapter DL seminar on “Guided Wave Devices: New Dimensions” being held on July 11th this year at Heriot Watt University in Edinburgh even though my term as DL would be over by June 30th. Since I am staying on in Scotland for the next two months, I accepted his invitation.
Overall visits to different LEOS chapters have been a great rewarding and stimulating experience for me. I learnt a lot from the scientists and students I met during these visits to different campuses. Within the time and budgetary constraints (which is important since I live in India – distance-wise far from the western world) I have tried to maximize visits to chapters, which were geographically wide spread as per the original suggestion in my DL offer letter. I wish I had more time in hand to visit the other 6-7 chapters, whose kind invitations I could not oblige. Those of you who could have some interest to the content of my talk, a video of my talk should now be available on LEOS portal: Education tab/LEOS University/Distinguished Lecturers. In all, I could visit a total of 13 LEOS chapters during my two-year term (2005-07) as a DL, which I greatly enjoyed. I feel this is a fantastic program of LEOS, which aims to network scientists in different countries, and provides great opportunity for exposing to students to various facets of contemporary research on Photonics in general.

“Microstructured Optical Fibre: An Emerging Technology and its Potentials”
Consequent to the mind boggling progress in high-speed optical telecommunication witnessed in late 1990s, it appeared that it would only be a matter of time before the huge theoretical bandwidth of 53 THz, offered by low-loss transmission windows in low water peak high-silica optical fibers would be tapped for telecommunication through dense wavelength division multiplexing techniques! In spite of this possibility, there has been a considerable resurgence of interest amongst researchers to develop application-specific specialty fibers, e.g. fibers in which transmission loss of the material would not be a limiting factor and in which nonlinearity and dispersion properties could be conveniently tailored to achieve transmission characteristics that are otherwise almost impossible to realize in conventional high-silica fibers. Research targeted at such fiber designs in the early 1990s gave rise to a new class of fibers, known as microstructured optical fibers (MOFs), which are characterized with wavelength scale periodic refractive index features across its cross-section. The periodicity could be realized by having a two-dimensional periodic array of low and high refractive index regions e.g. air holes embedded in a solid dielectric like fused silica glass. These structures exhibit photonic bandgaps i.e. they forbid propagation of a certain band of wavelengths within them. If the frequency of incident light happens to fall within the photonic bandgap, which is characteristic of these fibers, then propagation of light is forbidden inside it. In contrast to the electronic bandgap, which is the consequence of a periodic arrangement of atoms/molecules in a semiconductor crystal lattice, a photonic bandgap arises due to a periodic distribution of refractive index in a PCF. However by introducing in the central region a defect to an otherwise periodic structure, light (within the bandgap) could be localized in the defect region thereby mimicking a fiber core. The defect region could be a medium of refractive index higher or lower (e.g. air) than the average refractive index of the surrounding layers. In the former case, light is guided by modified total internal reflection due to the average refractive index of the cladding being lower than the central defect region. In case of lower refractive index defect, the corresponding MOFs are known as photonic bandgap fibers (PBGFs). In contrast to a conventional optical fiber, in which light is guided by total internal reflection, Bragg scattering is responsible for effective wave guidance in such fibers, which led to the christening of these fibers as photonic bandgap guided optical fibers. In 1987 in the same issue of Physical Review Letters, Eli Yablonovitch and Sameer John independently proposed for the first time the possibility of controlling properties of light through the photonic bandgap effect in man-made photonic crystals. Microstructured optical fibers have been a fall out of that research. The talk would focus on basic functional principle of optical wave guidance in such fibers vis-a-vis conventional fibers. Details of propagation and design & technology of 1D photonic band gap Bragg fibers would be described, in which we have recently made some research contributions and our collaborators in Russian Academy of Science have succeeded in fabricating some of our designed fibers. Discussions on applications would include designs of dispersion compensating fibers, fibers for metro networks, nonlinear spectral broadening in them and generation of supercontinuum light.
Bishnu P. Pal obtained M.Sc. and Ph.D. degrees in Physics from Jadavpur University (Kolkata) and IIT Delhi in 1970 and 1975, respectively as a National Science Talent Search Scholar. In late 1977 he joined the academic staff of IIT Delhi as a specialist on Fiber Optics, where he is a Professor of Physics since 1990. He has worked as Visiting Professor at the Norwegian Institute of Technology, Trondheim (Norway), University of Strathclyde, Glasgow (UK), Optoelectronics Research Center at City University of Hong Kong, and Universities at Nice and Limoges (France), the Fraunhofer Institute für Physikalische Messtechnik, Freiburg (Germany) as Alexander von Humboldt Fellow, and the National Institute of Standards and Technology, Boulder (USA) as a Fulbright Scholar, for various periods. He has been a founding member of International Journal of Optoelectronics (Taylor & Francis, UK) and he is currently a Member of the Editorial Advisory Boards of the journals: J. Elect. Engg. & Tech. (Korea), Optoelectron. Letts. (China), and IETE Students Journal (India). Prof. Pal has extensive teaching, research, sponsored R&D, and consulting (for Indian and US industries) experience on various aspects of Fiber Optics and related components and he has published and reported over 130 research papers and research reviews in international journals and conferences and has coauthored one each Indian and US patents. He is co-author of the book entitled Fiber Optics and Instrumentation (in Russian, Mashinostroenie Publishing House, Leningrad, 1987) and has edited the books: Fundamentals of Fiber Optics in Telecommunication and Sensor Systems (New Age Publications, New Delhi and John Wiley, New York, 1992, 4th reprint 2006) and more recently “Guided Wave Optical Components and Devices: Basics, Technology, and Applications (Academic Press/Elsevier, Burlington, 2006). He has also contributed 11 chapters in other books and monographs. He has been deeply involved with the conception and development of the Fiber Optics Laboratory at IIT Delhi in late 1970s. Prof. Pal is a Fellow of IETE (India) and Optical Society of India, Foreign Member of the Royal Norwegian Society of Sciences and Letters Academy (Norway), and is a Member of the Optical Society of America and IEEE/Laser and Electrooptics Society (USA). He has been an invited speaker at over 24 international conferences and he has been a member of the Technical/Advisory Committees of over 15 International Conferences. He is a co-recipient (with K. Thyagarajan) of the First Fiber Optic Person of the Year award in 1997 instituted by Lucent Technology in India for his significant contributions in all-fiber branching components for optical networks and also the Gowri Memorial Award for the year 1991 of IETE (India) for his paper (co-author B.D. Gupta) on fiber optic biosensors. He is currently also a Traveling Lecturer of OSA for his significant contributions to Guided Wave Optical Components and Devices. His current research interests concern guided wave optical components for DWDM and optical networks, gain flattening in EDFAs, specialty fibers like dispersion compensating fibers, and microstructured optical fibers, and also fiber optic sensors, optrodes, and near field fiber probes. Prof. Pal is running a 3-year term as a Member of the International Council of the Optical Society of America effective January 2007.


David V. Plant

It has been an honor and pleasure to serve as a LEOS Distinguished Lecturer for my second term in 2006 – 2007. I have had the pleasure of visiting several LEOS chapters throughout Canada and the Europe and I plan to continue visiting as an Emeritus Distinguished Lecturer. I have visited and given talks at the following Chapters: Benelux Chapter to participate in the Annual Symposium of LEOS which is held every year, Vancouver, British Columbia as part of the Canadian Conference of Electrical and Computer Engineers, and Ottawa as part of the Agile All-Photonic Networks Annual Research Review.
Summary of Lecture
Agile All-Photonic Networks
Abstract: Recent advances in fiber optic technology have prompted researchers to envision a future all-photonic network that is capable of supporting multiple access and services at very high bit rates. The confluence of optical transmission and optical network functions opens up new paradigms for network architectures that are enabled by emerging photonic technologies. Characteristics of these architectures and technologies that distinguish them from existing ones include: (1) networks in which the transmission of information is based on optical packets (burst-switched or packet-switched networks, with and without all-optical header recognition), (2) optical code-division multiplexing for allocating bandwidth-on-demand in bursty, asynchronous traffic environments, and (3) practical implementations for optical generation, shaping, and processing. The bursty nature of these networks imposes new design constraints on transmitters, receivers, and optical components. We review various system and technology considerations for such networks.
Bio: David V. Plant received the Ph.D. degree in electrical engineering from Brown University, Providence, RI, in 1989. From 1989 to 1993, he was a Research Engineer with the Department of Electrical and Computer Engineering at UCLA. He has been a Professor and Member of the Photonic Systems Group, the Department of Electrical and Computer Engineering, McGill University, Montreal, QC, Canada, since 1993. Since September 1, 2006, he has been the Chair of the Department of Electrical and Computer Engineering. During the 2000 to 2001 academic years, he took a leave of absence from McGill University to become the Director of Optical Integration at Accelight Networks, Pittsburgh, PA. He is the Director and Principal Investigator of the Centre for Advanced Systems and Technologies Communications at McGill University (www.sytacom.mcgill.ca). He is also Scientific Director and Principal Investigator of the Agile All-Photonics Networks Research Network (www.aapn.mcgill.ca). Hi research interests include optoelectronic-VLSI, analog circuits for communications, electro-optic switching devices, and optical network design including OCDMA, radio-over-fiber, and agile packet switched networks. Dr. Plant has received five teaching awards from McGill University, including most recently the Principal’s Prize for Teaching Excellence (2006). He was named an inaugural James McGill Professor, an IEEE Distinguished Lecturer, was the recipient of the R.A. Fessenden Medal and the Outstanding Educator Award, both from IEEE Canada, and received a NSERC Synergy Award for Innovation. He is a member of Sigma Xi, a Fellow of Optical Society of America and a Fellow of the IEEE.


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