Color demultiplexer using angularly multiplexed volume holograms as a receiver optical end for VLC based on RGB white LED

The visible light communication (VLC) based on RGB white LED can obtain high communication rate, because the RGB white LED light source has a wide bandwidth by modulating each color respectively. The receiver optical end of the VLC system based on RGB white LED is commonly composed of three optical filters and three lenses. However, it is relatively large size and no integration. In this paper, we propose and experimentally demonstrate a simple and efficient color demultiplexer based on the volume holographic gratings that can separate RGB light and focus each color on different directions. The expression of the volume holographic grating vector with curved interference fringes is derived. There is an important discovery that spectral selectivity and angular selectivity change on the different positions of volume holographic grating. The filtering property and diffraction efficiency of color demultiplexer are measured and analyzed.