Design of a four-channel demultiplexer based on photonic crystals with an ultra-high quality factor

In this paper, a four-channel demultiplexer based on photonic crystals with an ultra-high quality factor is realized by simulation. The plane-wave expansion and finite element method are used to characterize the photonic band structure and investigate the optical propagation behaviors, respectively. Through optimizing the resonator structure and material parameters, the ultra-high quality factor Q of 9082 can be obtained. Furthermore, using the designed resonator, the average quality factor Q of the four-channel demultiplexer can be realized as high as 8901. In addition, the footprint of the device is 324µm², the average channel spacing is 0.77 nm, the crosstalk between channels has values from -9.9 to 30.1 dB, and the average transmission is 88.86%. Particularly, the average Δλ is 0.17 nm, which leads to the ultra-high quality factor. The ultra-high quality factor makes the proposed demultiplexer promising for future on-chip optical integration.