Wideband, low loss Terahertz propagation through kagome air-core microstructured fibers

We present Terahertz (THz) time domain spectroscopy measurement of low loss microstructured kagome fibers using specially designed THz lenses. Losses as low as 0.6 cm^-1, 20 times lower than the fiber cladding material loss have been achieved. Single-mode propagation in the air core with very low dispersion is experimentally observed for these fibers. Comparison between two different core diameters of kagome fiber reveals that a wider transmission window can be achieved with a larger diameter while the propagation loss remains in the same order of magnitude.