lisper-bjorn@CS.YALE.EDU (Bjorn Lisper) (06/09/88)
In article <1933@uhccux.uhcc.hawaii.edu> garvin@uhccux.UUCP (Jay Garvin) writes: >How many of you have heard of photonic switching? .... I'm not an expert but I do have some impressions of this. I'll comment below on the points where I have something to say. >2. Should we really be letting photons do our computing for us? I see no moral reasons to say no. Photons should have to work as well as electrons. :-) > What are the forseeable problems with this technology? Size. I think the size of an optical switch is in the millimeter range right now whereas electronic switches are in the micrometer and sub-micrometer range. This is absolutely necessary to improve if optical computing is to have any substantial impact. > What types of things are promising about photonic switching besides > the speed? Communication seems easier to facilitate. In electronics wiring is a problem, long wires occupy precious area and slow down the circuit. Thus you want to connect physically close cells only. In optics the speed of light is the limit. I've seen a proposal how to arrange a parallel optical computer where the processors are in a plane. Over them is a mirror and they communicate by sending a laser beam so that it bounces off the mirror to the right recepient. In this communication scheme all processors are equally close w.r.t. communication regardless of physical proximity. Optical computers will be more resistant to electrical disturbances such as static electricity, solar wind bursts and EMP. This is by the way the reason fibre optics is used today for computer communication in electrically noisy environments such as factories. I've heard that the same optical switch actually can switch signals carried by light of different frequencies simultaneously. If this is true it will open new possibilities for parallelity, where computations can take place simultaneously not only in different processors but actually in *the same* one. >3. How long before one of these things gets off the drawing board and > into production? Some years ago a Californian company by the name of, I think, Guiltech, was developing a systolic array type parallel processor with optical computing elements. Apparently they dropped the project since nothing has been heard since. I don't think they dropped it for technical reasons, however, but rather since the price/performance quotient wasn't good enough. Bjorn Lisper
johng@ecrcvax.UUCP (John Gregor) (06/21/88)
In article <1933@uhccux.uhcc.hawaii.edu> garvin@uhccux.UUCP (Jay Garvin) writes: >How many of you have heard of photonic switching? Everybody?...Great! >Ok, I would like to find out what the latest research is in this area >and who's doing it. Well, this isn't exactly recent (1983), but I though it was interesting. First the title of the paper: A 100,000 gigabyte on-line storage system Marc A. Friedlander Advanced Technology Laboratories 8027 Leesburg Pike, Suite 700 Vienna, Virginia 22180 It appeared in a SPIE proceedings back in 83. The proceedings title was "Optical Mass Storage" or "Mass Storage Devices" or something to that effect. A keyword search should find it quickly. Sorry, I only photocopied the article. I don't know SPIE's copyright policy, or I would post more. But here is the abstract and introduction form the paper. ABSTRACT Nanosecond read, write and access times, system volumes of one cubic foot, and costs of 1E-8 cents per bit characterize this new volumetric optical technology. INTRODUCTION We report a new optical storage technology (patent pending), and its applications, which can provide 100,000 gigabytes of on-line storage with nanosecond read and write times, nanosecond access times, and in a volume of one cubic foot. The high storage density, and consequent short access time, is accomplished by three dimensional storage within an unstructured bulk storage medium at a storage density of one cubic micron per bit using visible light. The storage is effected by the photon echo phenomenon(1) which decisively surmounts the problems faced by previous volumetric optical storage approaches. End user cost for production versions will be $100,000 (or 1E-8 cents per bit). The Navy is examining the development of a prototype for application to tactical air reconnaissance. The prototype will allow tactical reconnaissance imagery to be received, processed and analyzed in ral time as an aid to command decision making. Ground based versions could be applied to the development of large, fully relational data bases due to the presence of inherent logic elements associated with each bit of the storage system. Highly parallel input and output capability as well as the ability to store analog data make it feasible to use the system as an efficient interface point between analog and digital optical information processing systems. 1. I.D. Abella, N.A. Kurnit and S.R. Hartmann, Phys. Rev. 141, 391 (1966) Now I have some questions: Q. Anybody know if this thing got built? Q. Is the idea a flop or is it currently classified? Q. Is the company still around? Q. Anybody with access to some nifty bibliographic search facilities want to tell me if this guy (or his company) has published anything more recently or with more substance? What papers have referenced this one? And, what are some other good references for optical memory? Q. What's state of the art? Q. How long until we won't have to worry about dram prices any more :-)? Q. Can we expect the Cray III (IV?, V?) to have 20cc of optical memory and occupy less space than a pee-cee? Comments from those more knowledgeable than me (not hard) are welcome. >7. Anybody know of some *good* references/journal articles in the area? > SPIE? SPIE is about the best I've seen. They are VERY prolific though. They have put out a few hundred proceedings since '82. They cover any field that ever interacts with a photon; from synthetic aperature optics to user intefaces to computer architecture etc. Q. Anybody know what a yearly subscription would cost? Thanks for any and all information. -- John Gregor johng%ecrcvax.UUCP@pyramid.COM