Perspectives in optical computing

30 years ago, the author was certain that electronics was reaching its natural limits and that optics alone could offer massive parallelism. In this article, he explains how he had it all wrong and how-after enduring a time of fear and doubt-he developed new confidence about the future of optics. Optics is dead, he says, only if we foolishly believe that its role is to replace electronics. All-optical computers are not the goal. In fact, the very concept is specious: an all-optical “computer” cannot import, modify or export information. So, the huge effort that has gone into the competition between optics and electronics has been a tragic waste of time, money and talent. Both optics and electronics have roles, but they are not the same. Whenever an optoelectronic computer competes directly with an electronic computer, it loses. Electronics is far more mature, far cheaper, far better funded. The hope for optics lies in doing things which are provably impossible for electronics. Presuming that such tasks exist and are worthwhile, optics plays an essential role