3D Printed Effective Single-Mode Terahertz Antiresonant Hollow Core Fiber

An antiresonant hollow core effective single-mode terahertz fiber is proposed and successfully fabricated with a photosensitive resin (SomosEvoLVe 128) by a 3D printer. The single mode characteristics of the fiber are found to be related to the area of the semielliptical tubes in the cladding. By optimizing the cladding structure parameters, a Higher Order Mode Extinction Ratio (HOMER) of above 6 can be achieved. A 30 cm long sample with optimized structural parameters is obtained by cascading two 15 cm long fiber samples fabricated by a 3D printer. The transmission loss and the electric field distribution are measured by a terahertz time domain spectroscopy (TDS) system. The electric field distribution measured at the output end of the fiber sample has the Gaussian profile, which accords with single-mode field distribution. Experimental results show that the average loss is 0.048 cm
^-1
within the frequency range from 0.2 to 1 THz, and the minimum loss is obtained as low as 0.009 cm
^-1
at the frequency of 0.82 THz.