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1 Introduction For centuries, light has been an important tool in mankind's technological development, but a marked discontinuity occurred in 1960 with the demonstra- tion of the laser. It was quickly seen that coherent light from lasers had potential application to communications, information processing, medicine and surgery, measurement, materials processing, and a variety of defense and scientific uses. These applications have been developed and are all now key elements of our technology, but the field is still a rapidly developing one with many new applications and improvements in existing applications possible. Recent rates of change are especially remarkable in employing light in com- munications and information processing, which is often referred to as "photon- ics." This study is concerned with that field. The proposal for this study stated: Recognizing the vital role of communication and information processing, the Board on Physics and Astronomy, through its Solid State Science Committee, proposes a 1-year assessment of the science and technologybase for photonics. The purpose of this study on photonics will be to define the field and present a descriptive yet concise report on the scientific and technology needs and opportunities over the next 10 years. The Photonics Science and Technology Assessment Panel was then set up with the following task: The Panel will address the following goals: (1) assessment of science and technology achievements to date; (2) identification of the areas of research that are currently ripe for development; (3) assessment of the prospects for their potential commercial applications; (4) assessment of the prospects for use of optical circuits in special 6
INTRODUCTION applications where existing technologies are in need of enhancement such as image processing and recognition, sorting, radar-array signal processing, and machine vision; and (5) assessment of the relationship to other active technology areas such as microelectronics and software. The audience addressed will be broad, including policy makers at the federal government level, in industry, and in academia. 7 The field of photonics is extensive and is growing very rapidly. Its present commercial size is several billion dollars with potential for growth to more than $100 billion. It is generally viewed as one of the key technologies of the information age. Fields such as optical signal processing, storage, and communications also have considerable potential for military applications. Thus the field of photonics must be viewed as strategically important both commercially and militarily. A workshop was set up in April 1987 featuring presentations from a number of experts. Recognizing that the field was too large to cover in all its aspects, the panel chose the following subjects for study by subcommittees: Telecommunications (Chapter 2) ~ Information Processing (Chapter 3) · Optical Storage and Display (Chapter 4) · Sensors (Chapter 5) It is believed that these cover important applications that also include representative opportunities and problems for the future. Although the division is by field of application, it is clear that much of the advance will be through new materials, new devices, and integration of elements (integrated optics and optoelectronics). Thus the critical enabling technologies are key parts of each of the chapters. In some applications, such as long-distance, high-data-rate information transmission, photonics is now the dominant technology. For other applica- tions, it is clear that electronics will remain superior for some time. It is tempting for an enthusiast to envision most things now done by electronics as being replaced by all-photonic systems, but electrons and photons are different, with different transmission and control properties. Electronics is well em- bedded in several dominant areas of information processing such as computing and switching. Very high levels of integration of electronic circuits have been obtained in manufacture. Many of the control functions common in electronics have yet to be demonstrated with photonic circuits, although the potential is great. It thus seems likely that photonics and electronics will be complementary and that optoelectronic circuits, which combine the advantages of photons with electrons, will be important for the foreseeable future. Of the policy issues considered by the panel, international competition in this field is clearly the most important to this country. It has become increas- ingly evident over the last few years that the countries that develop and use high
8 PHO TONICS technology in their industries will control the world economy. The United States has seen its lead in high technology slip in many fields. Although the NRC, the National Academies of Science and Engineering, and various government agencies have studied the competitiveness issue, a resolution of the issue has been elusive and it remains a critical matter. For photonics, the United States has been a leader in research and invention but is already a follower--or worse, an observer--in developing many of the commercial products of the field. The products from abroad are too often cheaper, more reliable, or of higher quality. The causes are too fundamental to be solved in any one field alone, but changes have to start somewhere. Chapter 6, "Policy Issues and Recommendations," includes some suggestions for such changes. ADDITIONAL READING Ausubel, J. H., and H. D. Langford, eds. 1987. Lasers, Invention to Application. Washington, D.C.: National Academy Press. Mayo, J. S. 1985. The evolution of information technologies. Pp. 7-33 in Information Technologies and Social Transformation, B. R. Guile, ed. Washington D.C.: National Academy Press. Mayo, J. S. 1986. Materials for information and communication. Scientific American 255~4~0ctober):59-65. 4. Bell, T. E. 1983. Optical computing: A field in flux. IEEE Spectrum 23(August):34-57. Miller, S. E., and A. G. Chynoweth, eds. munication. New York: Academic Press. 6. Tsang, W. T., ed. 1985. Lightwave Communications Technology. Parts A, B. C, and D of Vol. 22 of Semiconductors and Semimetals deal with a variety of technical issues concerned with materials, devices, and systems. See also a special issue of Physics Today devoted to optoelectronics, Vol. 38, No. 5, May 1985. 8. Popular magazines devoted to photonics include Laser Focus, Photonics Spectra,andLightwave. See also Appendix C. 9. Many regular journals are concerned with photonics, and numerous review articles or special issues of other journals have reviewed the state of the art. Additional sources of information on photonics are listed in Appendix C. 1979. Optical Fiber Com-