Positive and negative weighted optical summation using stimulated Brillouin scattering

Stimulated Brillouin scattering (SBS) is an interaction of two optical waves (pump and Stokes) and, an acoustic wave. The scattered wave is down shifted in frequency and the scattered photons are in phase. Weighted additions and subtractions are needed in many situations. For example, a neuron performs weighted summation of the incoming signals. The performance of such a device will enhance if it operates optically. In the following, it is shown that energy can be added to or subtracted from an optical signal via SBS in an optical fiber. In an optical fiber, the Stokes wave due to SBS travels in the backward direction only