Optical Solver of Combinatorial Problems: Nano-Technological Approach
  We report the first steps in creating an optical computing system. This system may solve NP-Hard problems by utilizing a setup of exponential sized masks. This is exponential space complexity but the production of those masks is done with a polynomial time preprocessing. These masks are later used to solve the problem in polynomial time. We propose to reduced the size of the masks to nano-scaled density. Simulations were done to choose a proper design, and actual implementations show the feasibility of such a system. 
Eyal Cohen, Shlomi Dolev, Sergey Frenkel, Boris Kryzhanovsky, Alexandr   Palagushkin, Michael Rosenblit, Victor Zakharov
cs.ET