Sub-Wavelength THz Plastic Fibers

In this report, we will review our recent development on the sub-wavelength plastic fiber for THz waveguiding. The proposed and demonstrated terahertz single-mode sub-wavelength waveguide is similar to an optical taper fiber, having a low attenuation constant (~10^-2 cm^-1), a high coupling efficiency, and a free-space direct coupling capability, comprised with a sub-wavelength PE fiber core with air cladding. The spectral characteristic of the sub-wavelength THz fiber will be discussed, with an effective attenuation minimum of THz waves on the order of or less than 10^-3 cm^-1 at a specific wavelength range which depends on the fiber diameter. More over, the application of the sub-wavelength plastic fiber will also be discussed, including a first demonstration of a singlemode fiber-based THz directional coupler.