We describe a technique that facilitates the design of digital optical
computers and other complex optical circuitry, such as optical
communications systems. Although there has been some discussion in the
literature of power budgeting in optical systems,[#!1!#,#!2!#] the treatment
has been limited to relatively uncomplicated applications, in which
heuristics and simple analysis are sufficient to estimate power loss and
cross talk of the system from the loss and cross talk of individual
components. The primary motivation for this research is to implement a
stored-program bit-serial optical computer,[#!3!#,#!4!#] containing hundreds
of components, interconnected in quite complex fashion. In such a system,
simple heuristics for power loss and cross talk estimation such as are
described in Refs. 1 and 2 are inadequate
because a given optical signal might take any one of a multitude of paths
before being detected and thus doing useful work. The methods developed
here are applicable to a wide variety of optical systems besides optical
computing systems, such as optical communications systems and optical
signal processors.
In a previous paper[#!5!#] we discussed the use of a graph-theoretic
technique for synchronizing optical systems that rely on time of flight
rather than latching or gating for synchronization. In this paper we
extend these graph-theoretic methods to the estimation of cross talk and
loss in optical systems.