Study On The Design And Application Of Terahertz Microstructure Optical Fiber

Terahertz(THz) wave is an electromagnetic wave,its frequency is between0.1THz and10THz,it’s in a certain condition that between microwave millimeter wave and infrared ray. There aremany characteristics of THz wave.Such as: the high transmission rate, high signal-to-noise ratio,very wide frequency, high safety, strong penetrating power and so on. These features make it havevery important academic and application value.But in the process of many of the existingexperiment, THz wave is spread in free space,the wastage of the THz wave propagation in freespace is very large,and the direction of propagation is not easy to control. In order to overcomethese defects, the waveguide of THz has very important research significance. Photonic crystal fiberhas a great deal of flexibility on the choice of structure and material.Transmission can be achievedin a relatively wide frequency range with low loss and low dispersion. This has a great advantagecompared with other waveguide. It is suitable for terahertz’s transmission.A kind of photonic crystal fiber which is suitable for the terahertz is designed and analysed byusing the finite element method (FEM). Research the transmission properties of optical fiber bychanging the hole spacing and the aperture size. The results show that loss decreases when the holespacing increases gradually, when Λ=220μm the loss reach the extremum.Loss decreases when thefirst layer of aperture gradually increases,and reach the extremum when d1=160μm. When the firstlayer pore size increases gradually，the value of the dispersion which under the same wavelengthincreases gradually.Under comprehensive consideration,when this kind of THz photonic crystalfiber works between2.1THz to2.3THz, Λ=220μm，d1=160μm，d2=210μm or d2=220μm，d3=180μm，d4=200μm，the loss value is lower than0.06dB/km, the dispersion value is between0.2ps/(nm·km) to0.27ps/(nm·km)，the dispersion slope is0.6ps/(nm·km2),the PCF can transmitwith high performance and long distance. The terahertz source coupled in photonic crystal fiber isdesigned and simulated by using ZAMAX. At larst, we get the theoretical maximum couplingefficiency which is about80.07%, and give the system diagram of terahertz waveguide transmissionsystem, analyse and calculate the loss of each component.