DESIGN OF ONE-DIMENSIONAL PHOTONIC QUASI-CRYSTAL ARRAYS FOR THE FLAT-BAND PASS FILTERS

We designed the one-dimensional photonic quasi-crystals (1D PQCs) arrays for application to the flat-band (FB) pass filters using a transfer matrix method (TMM). In this work, the PQCs of the combinations of SiO₂-TiO₂ and SiO₂-ITO were designed with the centre wavelength of 1.550 µm at an incident angle of 8°. The width of flat-transmission bands increases with increasing the number of cavity. For a SiO₂/TiO₂–based PQC with 3-cavity structure, the FB-width was evaluated to be about 0.7 nm and the insertion loss was approximately 0.3 dB. In addition, the band-center wavelength exhibited a blue shift with an increase of incident angle and their band widths are uniform for specific θ_i-ranges. An application of this FB-pass filter to a wavelength division multiplexing (WDM) device was also proposed. We believe that the PQC-based devices could be comprehensively applied to the new conceptional optical passive and active devices.