基于磁光子晶体的低损耗窄带THz滤波器

本文提出一种采用石榴石型铁氧体磁性材料的太赫兹滤波器,利用波导线缺陷和腔内点缺陷的耦合特性,通过改变腔内介质柱半径及分布,实现对某个波长的耦合,达到了高效率滤波的功能;改变外磁场的大小,影响铁氧体材料的磁导率变化,使谐振频率发生改变,从而对THz波进行滤波.应用平面波展开法(PWM)和时域差分有限法(FDTD)进行仿真分析,研究结果表明,该滤波器其插入损耗为0.0997 d B,3 d B带宽为8.22 GHz,实现了低损耗窄带滤波.

Low loss and narrow-band THz filter based on magnetic photonic crystals

As a key point to applying and studying magnetic photonic crystal technology, communication devices such as the magnetic photonic crystal filters with high performance and easy integration are developed. We investigate the feasibility of ferrite magnetism materials that can be used to make photonic crystal filters. The optical properties of the magnetic materials may be tuned by adjusting the magnetic field or temperature. The band gap of the magnetic photonic crystal can thus be transferred by changing the external magnetic field. This kind of magnetic photonic crystal has a great application prospect. A low insertion loss and narrow-band filter is designed based on a magnetic field-controlled ferrite defect in a photonic crystal for a terahertz (THz) wave. Ferrite is a ferromagnetic metal oxide with high dielectric constant, low saturation magnetization intensity, and high magnetic permeability at high frequencies. According to the crystal structure it can be divided into three categories: spinel, garnet and magnetic rock types. The garnet ferrite crystal can be used to realize THz band transmission, and its absorption coefficient is low (0.05-0.3) in uniform polarization. In this paper, a novel magnetic THz photonic crystal filter is proposed, in which point defects are produced by the introduction of garnet ferrite magnetic materials. Based on the coupling characteristics between the linear defect wave guide and the point defects, THz wave with a certain wave length can be well coupled by changing the radius and arrangement of the resonant cavity, so as to achieve high efficiency filter function. The permeability properties of ferrite magnetic materials are changed with the variation of the intensity of the external magnetic field, and the tuning of the frequency of the resonance mode. The optical properties of the filter are analyzed in detail by using plane waves method(PWM) in finite difference time domain(FDTD). Simulation results show that by changing the point defect structure and the radius of a certain dielectric cylinder, the insertion loss and 3 dB bandwidth of the filter are 0.0997 dB and 8.22 GHz, respectively.