Eight-channel all-optical demultiplexer based on photonic crystal resonant cavities

In this paper, we propose a new structure based on photonic crystals to realise a demultiplexing operation for dense wavelength division multiplexing transmission systems. To obtain high quality factor, we used arc cavities and a quality factor as high as 4860 was achieved. In the designed demultiplexer, the main cavity was responsible for selecting the wavelength. By changing the boundary rods condition of each cavity, the modes could resonate at the desired frequencies. As we wanted to see just one sharp wavelength at the output of each channel, an arc cavity was imposed in a way that by bringing other modes to the input waveguide, the wavelength selection improved (and the feedback was investigated). Based on the results, the average pass bands of channels are near to 1.5 nm and the channel spacing is approximately 1.75 nm. The proposed demultiplexer acts in a near-complete transmission efficiency and the mean value of the crosstalk was −18 dB.