An energy-efficient free-space optical interconnection for clock distribution

An energy-efficient free-space clock-distribution scheme for intrachip and chip-to-chip application is proposed here. The scheme involves two aspheric mirrors in confocal configuration. The length between the mirrors should be equal to the length traversed by an optical ray in one or an integer multiple of the clock period for ghost-free clock reception. The proposed method reuses the unused optical energy of a clock pulse scattered over the nonphotodetector area of the chip by synchronously combining with the optical energy of the successive clock pulses. Zero clock skew can be achieved by this method. © 1995 John Wiley & Sons, Inc.