Subwavelength Dielectric-Fiber-Based THz Coupler

We demonstrate a terahertz (THz) directional coupler for future THz applications including THz power dividers, THz communications, and THz fiber-endoscopes. By using subwavelength polyethylene fibers, we successfully established a single-mode fiber-based THz directional coupler. Unlike traditional directional couplers, the demonstrated subwavelength directional fiber coupler shows less dependency on the overlapped length of two fibers and the delivered THz frequency in our interested minimal-attenuation wavelength regime. By tuning the geometry, we also show the feasibility to control the coupling ratio.