The Study On Multi-wavelength THz Filter Based On Resonance Coupling Photonic Crystals

THz wave is the electromagnetic wave whose frequency ranges from 0.1THz to 10 THz. It is a good broadband information carrier. Because of its special frequency band, its direction and penetrating has great potential in terms of communication. Photonic crystal has characteristics of photonic band gap and photon localization. Using photonic crystal technology for making THz communication devices THz filter is of great significance.In this paper, combining photonic crystal technology and THz technology, a kind of multiple wavelength THz photonic crystal filter based on resonance coupling is proposed. First, the basic principle of THz 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 ring cavity is designed. After that, the effect of different structures of ring cavity towards the performance of the filter is analyzed. By changing the radius and refractive index of internal dielectric cylinder, the radius of the scattering dielectric cylinder and so on, it can filter different wavelengths of THz wave. After optimization, we get a photonic crystal ring cavity filter with 4×3 internal dielectric cylinders and four scattering 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 square lattice photonic crystal is larger, the corresponding wavelength is 65.265~88.613μm.The multiple wavelength THz photonic crystal filter based on resonance coupling can filter four wavelengths. They are 82.086μm( the frequency of 3.654THz), 83.168μm(the frequency of 3.607THz), 84.457μm(the frequency of 3.552THz) and 85.601μm(the frequency of 3.505THz). The corresponding frequency band width is: 0.0017THz、0.0009THz、0.0016 THz and 0.0013 THz. The filtering efficiency of the filter is almost close to 100%. Insertion loss is lower than 0.1dB. Channel isolation is close to 20 dB. 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.