基于光子晶体自准直效应的太赫兹偏振分束器设计

Design on Terahertz Polarization Beam Splitter Based on Self-Collimating Effect of Photonic Crystal

提出了一种新型、紧凑的光子晶体太赫兹(THz)偏振分束器,利用自准直效应实现横电(TE)模和横磁(TM)模的无衍射传输,利用禁带特性实现TE模和TM模的分离。基于平面波展开法和时域有限差分法对太赫兹偏振分束器的性质进行仿真建模分析,结果表明,该偏振分束器在2.9~3.01THz频率范围内可实现偏振分离;频率为3THz时,TE模的反射率和TM模的透射率均高于90%,TE模和TM模的消光比分别高达19.9dB和26.24dB。此外,与以往的光子晶体太赫兹偏振分束器相比,所提出的偏振分束器设计简单,更易于实现(无需引入缺陷),尺寸更微小(650μm×650μm),带宽更宽(2.9~3.01THz)。

A novel and compact terahertz（THz）polarization beam splitter based on photonic crystal is proposed.Transmission without diffraction of transverse electric（TE）and transverse magnetic（TM）modes is realized by using the self-collimating effect,while the separation of TE and TM modes is realized by using the band gap characteristic.The characteristics of the terahertz polarization beam splitter is simulated and analyzed by using plane wave expansion method and time domain finite difference method.The results show that the polarization beam splitter can realize polarization separation in the frequency range of 2.9-3.01 THz.While the frequency is 3 THz,the reflectivity of TE mode and the transmittance of TM mode are both higher than 90%.The extinction ratios of TE and TM modes are 19.9 dB and 26.24 dB,respectively.Moreover,compared with the previous photonic crystal terahertz polarization beam splitters,the proposed polarization beam splitter is simpler to design,easier to realize（without defects）,smaller in size（650μm×650μm）and wider in bandwidth（2.9-3.01 THz）.