太赫兹偏振分束器的结构设计和性能研究
发布时间：2018-10-09 19:57
【摘要】：太赫兹波(Terahertz,简称THz),是指频率在0.1~10THz范围内的电磁波,在通信、成像和空间探索等方面应用广泛。偏振分束器是光学系统中一种重要器件,可将光信号分离成两个相互正交的偏振光,并沿着不同路径传输,设计性能优良的THz偏振分束器对于THz器件的研究具有重要意义。本文基于双芯光纤和光子晶体设计了两类THz偏振分束器,具体研究如下:(1)基于双芯光纤的THz偏振分束器:设计了两种基于领结型多孔光纤的双芯THz偏振分束器,分别采用填充法和调整结构法实现折射率反转匹配耦合,达到偏振分离的目的。采用有限元法建模仿真,结果表明:两者的频率工作范围均为0.5~2.5THz;在f=0.5THz时,两者分离长度最短,分别为0.437cm和0.428cm,且此时两者的x-和y-偏振模损耗也最低,分别为0.037dB、0.039dB和0.033dB、0.033d B;x-和y-偏振模的消光比最高分别为25.16dB、24.92dB和22.94dB、20.51dB。两者相比,填充法的THz偏振分束器的消光比整体较高;而调整结构法的THz偏振分束器在高频处的分离长度及损耗更具优势,且操作方便,制作简单。(2)基于光子晶体的THz偏振分束器:设计了两种光子晶体THz偏振分束器,分别利用禁带特性和自准直效应与禁带特性结合的方式实现偏振分离。采用平面展开法和时域有限差分法建模仿真,结果表明:前者频率工作范围为2.8125~2.865THz,TE模和TM模的消光比最高可达25.2dB和25.4dB,其透射率均高于95%;后者频率工作范围为2.9~3.01THz,TE模和TM模的消光比最高可达19.9dB和26.24dB,TE模的反射率和TM模的透射率均高于90%。两者相比,基于自准直效应与禁带特性结合所设计的偏振分束器更易于实现(无需引入缺陷),带宽更宽。将两类THz偏振分束器相比较,基于光子晶体的THz偏振分束器的尺寸更小,但运行的带宽远不如基于双芯光纤的THz偏振分束器。
[Abstract]:Terahertz wave (THz),) is the electromagnetic wave with frequency in the range of 0.1~10THz, which is widely used in communication, imaging and space exploration. Polarization beam splitter is an important device in optical system. The optical signal can be separated into two mutually orthogonal polarized light and transmitted along different paths. The design of THz polarization splitter with excellent performance is of great significance to the research of THz devices. In this paper, two kinds of THz polarization beam splitters are designed based on dual-core fiber and photonic crystal. The main contents are as follows: (1) THz polarization splitter based on dual-core fiber: two kinds of dual-core THz polarizer based on bow type porous fiber are designed. The refractive index inversion matching coupling is realized by filling method and adjusting structure method respectively, and polarization separation is achieved. The finite element method is used to model and simulate. The results show that the frequency range of both is 0.5 ~ 2.5THz, the separation length of the two is the shortest, 0.437cm and 0.428 cm, respectively, and the loss of x- and y- polarization mode is the lowest in the case of f=0.5THz. The highest extinction ratios of 0.037 dB and 0.033 dB and y- polarization mode are 25.16 dB and 22.94 dB respectively. Compared with the two methods, the THz polarization splitter with filling method has a higher extinction ratio, while the THz polarization splitter with adjusting structure has more advantages in separation length and loss at high frequency, and is easy to operate. Simple fabrication. (2) THz polarization beam splitter based on photonic crystal: two kinds of photonic crystal THz polarization splitter are designed. Polarization separation is realized by combining band gap and self-collimation effect with forbidden band characteristic respectively. The plane expansion method and the finite-difference time-domain method are used to model and simulate. The results show that the extinction ratio of the former frequency range is 2.8125 ~ 2.865 THZN te mode and TM mode, the highest extinction ratio of 25.2dB and 25.4dB is higher than 95 dB, while the latter frequency range is 2.9 ~ 3.01THznte mode and TM mode, the extinction ratio of 19.9dB and 26.24dBTE mode is up to the highest and the reflectivity of TM mode is up to 26.24dBTE mode. The transmittance of the modes is higher than 90. The polarization splitter based on the combination of self-collimation effect and band gap is easier to realize (without introducing defects) and the bandwidth is wider. Compared with two kinds of THz polarization splitter, the size of THz polarization splitter based on photonic crystal is smaller, but the bandwidth is much lower than that of THz polarization splitter based on dual-core fiber.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O441.4;TN253
本文编号：2260592
[Abstract]:Terahertz wave (THz),) is the electromagnetic wave with frequency in the range of 0.1~10THz, which is widely used in communication, imaging and space exploration. Polarization beam splitter is an important device in optical system. The optical signal can be separated into two mutually orthogonal polarized light and transmitted along different paths. The design of THz polarization splitter with excellent performance is of great significance to the research of THz devices. In this paper, two kinds of THz polarization beam splitters are designed based on dual-core fiber and photonic crystal. The main contents are as follows: (1) THz polarization splitter based on dual-core fiber: two kinds of dual-core THz polarizer based on bow type porous fiber are designed. The refractive index inversion matching coupling is realized by filling method and adjusting structure method respectively, and polarization separation is achieved. The finite element method is used to model and simulate. The results show that the frequency range of both is 0.5 ~ 2.5THz, the separation length of the two is the shortest, 0.437cm and 0.428 cm, respectively, and the loss of x- and y- polarization mode is the lowest in the case of f=0.5THz. The highest extinction ratios of 0.037 dB and 0.033 dB and y- polarization mode are 25.16 dB and 22.94 dB respectively. Compared with the two methods, the THz polarization splitter with filling method has a higher extinction ratio, while the THz polarization splitter with adjusting structure has more advantages in separation length and loss at high frequency, and is easy to operate. Simple fabrication. (2) THz polarization beam splitter based on photonic crystal: two kinds of photonic crystal THz polarization splitter are designed. Polarization separation is realized by combining band gap and self-collimation effect with forbidden band characteristic respectively. The plane expansion method and the finite-difference time-domain method are used to model and simulate. The results show that the extinction ratio of the former frequency range is 2.8125 ~ 2.865 THZN te mode and TM mode, the highest extinction ratio of 25.2dB and 25.4dB is higher than 95 dB, while the latter frequency range is 2.9 ~ 3.01THznte mode and TM mode, the extinction ratio of 19.9dB and 26.24dBTE mode is up to the highest and the reflectivity of TM mode is up to 26.24dBTE mode. The transmittance of the modes is higher than 90. The polarization splitter based on the combination of self-collimation effect and band gap is easier to realize (without introducing defects) and the bandwidth is wider. Compared with two kinds of THz polarization splitter, the size of THz polarization splitter based on photonic crystal is smaller, but the bandwidth is much lower than that of THz polarization splitter based on dual-core fiber.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O441.4;TN253
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