Development of 2.5 THz suspended porous microstructured fiber based on cyclic-olefin copolymer

Efficient transmission of terahertz (THz) wave is very important in the development of THz technology. Polymer microstructured fiber is ideal in THz waveguide transmission for its advantages of low loss, low dispersion and good flexibility to bend. Based on the full vector finite element method, a suspended porous microstructured fiber with the operating frequency of 2.5THz was designed. Fiber samples made of cyclic-olefin copolymer were fabricated, and their transmission performances were measured by using the CO2 pump laser THz source. The measured minimum loss is 0.17dB/cm and average loss is about 0.5dB/cm. The fluctuation of transmission loss is less than 5% when the fiber is bent from 0° to 90°, showing good flexibility of bending. The measured mode field distributions of the output tips show that the THz wave propagates with fundamental mode, and the energy is well confined in the core of the fiber.