Study Of Photoconductive Antenna Terahertz Source And Its Transmission Characteristics In Optical Fiber

The terahertz (THz) region lies between the millimeter and infrared region, with frequencies ranging from 0.1 THz to 10 THz. They have very important scientific and application values because of their unusual region and various characteristic parameters. However, there are great difficulties in generation and transmission of electromagnetic fields at these wavelengths. Terahertz radiation wave should have greater radiation power and lower confinement loss. Photoconductive antenna can meet these requirements of higher radiation power and higher optical conversion efficiency. Meanwhile, the transmission characteristics of terahertz in photonic crystal fiber (PCF) had discussed. The PCF which distinguished from the traditional optic fiber has the characteristics of the single endless mode to deliver, the adjustment of dispersion, the high modal birefringence and low loss and so on. We designed a novel terahertz photonic crystal fiber, which have the characteristics like:the high modal birefringence, single mode single polarization, low dispersion and low loss. A new method is provided for future research.In this article, the main contents are as follows:Firstly, we summarized the characteristics and applications of terahertz wave and the progress of conductive antenna and terahertz photonic crystal fiber.Secondly, we introduced the theoretical models of mechanism of terahertz radiation. THz near-field and far-field expressions were derived in detail according to Maxwell’s electromagnetic theory. We summed up the impact of photoconductive antenna to generate a terahertz wave power factor.Thirdly, the laser pumping power and the applied bias voltage on the photoconductive antenna to generate THz wave power influence were studied by both simulation and experiments.Fourthly, the theory of finite element method (FEM) is introduced. Using FEM, we discussed the impact element on the transmission characteristics of THz-PCF.Finally, based on above research, we designed a high modal birefringence, single mode single polarization, low dispersion and low loss of total internal reflection terahertz photonic crystal fiber.