1x4 Visible Light MMI Wavelength Demultiplexer in GaN slot-Waveguide Structure

High transmission losses is the main problem that limits the performances of visible light networking system that work on wavelength division multiplexing (WDM) technique. In order to overcome this obstacle, we propose a new design for a 1x4 visible light multimode interference (MMI) demultiplexer based on a slot-waveguide structure that operates at 547 nm, 559 nm, 566 nm and 584 nm, Silica (SiO2) and Gallium-nitride (GaN) were found to he low-loss materials for the slot waveguide structure. Results show that the MMI demultiplexer can transmit 4-channels that work in the visible light range with a large bandwidth of 1.8-3.2 nm, low transmission loss of 0.983-1.423 dB and crosstalk of 13.8-18.3 dB, Thus, the proposed device can be very helpful in visible light communication (VLC) system that works on WDM technique.