The Study On The Characteristics Of THz Filter Based On Two-dimensional Magnetic Photonic Crystals

THz wave is the electromagnetic wave whose frequency ranges from 0.1 THz to 10THz. It is a good broadband information carrier. Because of its special frequency band, its direction and penetrating has great potential in terms of communication. Magnetic photonic crystal is a kind of photonic crystal composed of magnetic photonic materials. Magnetic photonic crystal has the characteristics of both magneto-optical effect and photonic crystal. Combining these two kinds of characteristics, the magnetic photonic crystal will show some unique properties. Using magnetic photonic crystal technology for making THz filter of THz communication devices is of great significance.In this paper, combining magnetic photonic crystal technology and THz technology, a kind of tunable THz filter based on magnetic photonic crystal is proposed. First, the basic principle of THz magnetic photonic crystal filter based on resonance coupling is analyzed. Then, on the basis on the structure, a simple square lattice photonic crystal structure combining straight waveguide and micro cavity is designed. After that, the effect of different structures of micro cavity towards the performance of the filter is analyzed. By changing the radius of internal dielectric cylinder and external magnetic field, the radius of the reflecting wall dielectric cylinder and so on, it can filter different wavelengths of THz wave. After optimization, we get a tunable photonic crystal micro cavity filter with 7 magnetic material dielectric cylinders. Finally, we use RSoft software to simulate the filter’s performance of different wavelengths of THz signal incident.The simulation results show that the bandgap of simple triangular lattice photonic crystal is larger; the corresponding wavelength is 66.62μm～107.15μm.The tunable wavelength THz photonic crystal filter based on magnetic photonic crystal technology can filter two wavelengths. They are 84.628μm (the frequency of 3.545THz) and 87.025μm (the frequency of 3.447THz). The corresponding frequency band width is:0.0029THz and 0.0034THz. The filtering efficiency of the filter is almost close to 90%. Insertion loss is lower than 1dB. Response time is around 2ns. The performance of the filter is excellent. The filter has extensive application prospect in the field of multiple wavelengths THz communication.