baker@necssd.NEC.COM (Larry Baker) (08/11/90)
[] Awhile back someone asked about an anonymous company creating an optical circut, and promising to deliver a finished application by 2000. AT&T demonstrated a *working* optical switching matrix at SuperComm in Atlanta, April of this year. They had two working prototypes at the show, with Bell Labs designers there pointing out salient features. I forget the details, but it was all written up in one of the IEEE rags around March 1990. I may have a copy of the article around my office; I'll look. Also, about a month before they announced the working switching matrix they announced a working adder built out of the same basic technology. One of the problems, they said, was that it could operate at speeds beyond their ability to test it, and they felt that optical computing at speeds that truly stretch the limits of the design materials would be a long time coming, due mainly to that problem. AT&T claims that they intend to deliver a working switching product using the optical matrix as its core switching fabaric, in 5 years. This is extremely audacious and probably unrealistic, but it just may be possible. One of the problems with the prototypes, however, was that it used an electronically pulsed laser to change the matrix connectivity, so the actual *switching* speed of the matrix fabaric cannot exceed the speed of the (electronic) control logic. Also, signaling for switching at such high bandwidth (gigabits/sec/channel) is effectively impossible, because electronics have to interpret it and respond with changes to the matrix, a double trip through the electro-optic bridge. My guess is that they'll use it for some kind of monster or broadband switch, with conventional 64kbps and ISDN/BISDN channels multiplexed through the matrix and a stored-program or hardwired computer telling it what to do. But, if you think about it, once very basic signaling and matrix management can be handled directly within the matrix fabaric (no electro-optic bridge), what you have is a hell of a fast multichannel bus. Think of some of the supercomputing applications that could take advantage of terabit connectivity, switched at bus speeds. It brings whole new meaning to parallel computing.... Cheers, LEB