The Design And Study On Characteristics Of THz Dual-wavelength Filter Based On Combination Resonator

Terahertz (THz) communication has the advantages of broadband, fine direction and lowdisperison. While the spectrum of wireless communication is not enough, the demand forbandwidth has been growing, THz communication will help to solve the problem. THz filter is oneof the most important devices in THz communication field. The photonic crystal technology hascommonly been used in the research of terahertz communication devices. With the extensiveapplication of dense wavelength division multiplexing in communication system, the study ofmulti-wavelength THz filter has played a significant role in communication field.This paper designs a new type of THz dual-wavelength filter based on combination resonator.Firstly, the paper studies the relevant theory and research methods of the photonic crystal.Introducting of combination resonantor composed by three point defects and line defect to a wholephotonic crystal, this paper designs a new type of THz frequency filter with the function ofdual-wavelength frequency selective. It uses the FDTD method to simulate and analyze theinfluences of two defect modes which is located in the combination resonantor of the new filter,transmission spectrum of the primary waveguide of the filter and that of the filter waveguide, inorder to optimize the structure parameters of the filter. In the end, this paper analyzes everyperformance indicators of the filter and draws the time-domain steady-state response graphs of eachof two wavelengths. The final result proves that the new filter designed by this paper can selectfrequences at3.413THz (87.9μm) and3.225THz (93.02μm), and the each efficiency of couplingtwo defect mode has reached more than95%, and that the light of primary waveguide has beenalmost completely coupled to the filter waveguide, so the filter can achieve high coupling efficiency.The response time of new filter to the87.9μm wavelength is about0.6ns, which to the93.02μmwavelength is0.2ns, so that the filter can be quickly into a stable state.The simulation results show that the Q value of the THz filter’s resonantor has reached morethan1,000, so the filter can achieves ultra-narrow band filter, and other features such as lowinsertion loss, large channel isolation, high filtering efficiency, fast response time and stronganti-jamming capability, which will have a good prospect in the terahertz high speedcommunication systems.