Single mode propagation through a terahertz kagome microstructured fiber

We report measurements for hollow core kagome microstructured Terahertz (THz) fiber characterized with the THz-time domain spectroscopy (THz-TDS). To achieve good mode overlap between the input beam and the fiber mode distribution, we incorporate specially designed THz lenses in our experimental setup. The experimental observations show that only the fundamental mode is guided in the fiber core. The time domain scans and their spectral information show air-guidance over a large frequency range from 0.6 to at least 1.1 THz. Within this frequency bandwidth, low transmission amplitudes at certain frequencies are identified as the frequency cut-offs for the kagome structure is observed. The measured transmission of the kagome fibers shows the characteristics of the inhibited coupling mechanism. We estimate high coupling efficiencies, as high as 60%, have been achieved in our experiments.