Volume holograms of co-orthogonal waves for optical channel switching and expansion of light waves in Walsh basis functions

Abstract Study is presented of the volume superposed holograms, recorded with the use of light waves, whose amplitudes can be described in terms of mutually orthogonal functions. In the experiment the possibility to use such holograms for switching of optical channels and for expansion in Walsh functions of the light waves was shown. One channel commutation to 8 output channels with a signal/cross-talk ratio of 15–25 dB and expansion of the light waves, scattered by objects consisting of 7 points, across the set of 8 Walsh functions were realized. On the basis of the evaluated expansion coefficients the real components of the complex amplitudes of the light field from the objects were found out. Mean square error of experimental values with respect to the theoretically predicted values was 4.2–8.8%. The theoretical study of the cross-talk, revealing itself in the case of frustrated orthogonality of the reference waves, was carried out. Signal wave intensity and cross-talk intensity and their relation were evaluated for the case of nearly 100% diffraction efficiency of the holograms and for the case of low diffraction efficiency. Light field expansion in the case of frustrated orthogonality of the reference waves was discussed.