In this paper, we present the coupled-wave analysis for multiple thick holographic gratings for optical beam combining. Starting with the basic model of incoherently superimposed multiple gratings used to form the beam-combiner, we derive equations that describe wave propagation in a holographic substrate containing angular multiplexed gratings with either sinusoidal refractive index or absorption modulation including the off-Bragg matched condition. Numerical results are presented for multiple thick holographic gratings in three different geometries: the beam-splitter mode, the beam-combiner mode, and the cross-coupled mode. The effect of non-equal beam intensities and phased angle variation on the efficiency of beam combiner have been investigated. Experiment is performed to create an efficient six beam splitter-combiner using a thick photopolymer based holographic material. The experimental measurement for efficiency in beam combining compares well with the predicted value from our theoretical model.
- Beam combiner
- Coupled-mode theory
- Holographic multiplexing
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics