A four green-light demultiplexer using a multi gallium nitride slot-waveguide structure

In this work, we introduce a four green-light wavelength splitter device, based on six slot-waveguide structures. Silica and gallium nitride materials were chosen for confining the green light inside the slot-waveguide area in a transverse magnetic field mode. The device functioned as a 1 × 4 demultiplexer, which demultiplexes wavelengths in the green-light band with wavelength range of 500–530 nm with an accurate spacing of 10 nm. The coupling between the six slot-waveguide units was analyzed using the classical mode theory and the full vectorial beam propagation method. Simulation results showed that the four wavelengths could be demultiplexed after a short coupling length of 106.5 μm with low losses around 0.108–0.127 dB, full width at half maximum around 8.99–9.39 nm, and excellent crosstalk around −21.13 to −24.1 dB. The device has the potential to increase data bitrate by utilizing the wavelength division multiplexing technique in visible light communication systems.