Implications of interconnection theory for optical digital computing.

Heat removal, rather than finite interconnect density, is the major mechanism that limits how densely we can pack three-dimensional computing systems of increasing numbers of elements. Thus highly interconnected approaches can be employed without a further increase in system size. The use of optical interconnections for implementing the longer connections of such systems is advantageous. In fact, if the optical communication energy is sufficiently low and large-bit repetition rates are employed, conductors are useful for only the shortest connections and can be dispensed with altogether with little disadvantage. This justifies consideration of an optical digital computer.