Design Of One Dimensional Photonic Crystal Narrowband Filter

WDM technology is a good solution to the problem of rapid growth of the optical fiber communication system transmission capacity.Compared with traditional filters,the photonic crystal filter has the advantages of simpler structure,smaller optical loss and easier integration,and has good prospects in optical filtering.At present,the photonic crystal mainly through the electro-optical,magneto-optical effect to achieve narrow-band filter,but this method is poor tuning,low transmittance,preparation process difficult.Based on the limitations of these photonic crystals,the paper proposes one-dimensional mirror,stack photonic crystal for narrowband filtering and defect-layer photonic crystal for ultra-narrowband filtering of WDM 1550nm window.The main contents are as follows:?1?Based on the propagation theory of electromagnetic wave in the medium,the band gap formation principle of multi-layer dielectric film is investigated by using transfer matrix method,and the transmittance and band gap of one-dimensional simple periodic and mirror photonic crystal are deduced.?2?One dimensional mirror photonic crystal?AB?^N?BA?^Nand stack photonic crystal?AB?^N?A₁ B₁?^Nare designed for applying to WDM 1550nm window narrowband filter,the band gap characteristics are simulated and the effects of different parameters on its filtering performance are investigated.The results show that changing the film cycle number,dielectric material and thickness can change the position?transmission and bandwidth of the narrowband window,changing the incident angle can make TE wave and TM wave of the mirror and stack photonic crystal separated,so as to achieve polarization filtering.?3?The mirror photonic crystal thin film was prepared.The experimental results show that the transmittance of the sample is less than 1%at 1350-1700nm?except 1551.4nm?,the transmittance is 92.727%at 1551.4nm and the relative bandwidth is 0.0058nm,has a good application prospect in near infrared band narrowband filtering.?4?Defect layer photonic crystal is designed for ultra-narrowband filtering at 1550nm window in WDM system.The influence of different parameters on the narrow-band filter performance is discussed.This provides a new idea for WDM near-infrared filtering.