Image amplification with local addressing by two-wave coupling in a Bi_12SiO_20 crystal by application of direct-current voltage

We present a proposal and an analysis of local image amplification by two-wave coupling in a Bi12SiO20 crystal by applying external dc voltage. The analogy of two-wave coupling to an optical transistor array is discussed. It is found through the experiments that the local gain in amplification is given not by the reference-beam pattern alone but also by the electric field that is formed by the local photoconductance of the Bi12SiO20 crystal. A resistance-network model is used for analysis of the electric-field distribution. A variety of experiments verify the theoretical and calculated analyses. A sample reference pattern for amplifying segments of a signal image is designed through the resistance-network analysis of the electric-field distribution.