Description
In this study, we have fabricated an oval-tube antiresonant HCF with an outer diameter of 4.56 mm × 5.25 mm with different lengths using a 3D printing method for D-band operation. The proposed design employs a non-uniform cladding to shift resonance frequencies and spatially distribute leakage, resulting in lower loss and a broader low-loss transmission window without altering the overall fiber outer diameter. We have numerically and experimentally validated the use of a thin metallic layer in increasing the signal strength, which strongly confines the signal at antiresonance frequencies. In this study, Topas was used as the dielectric material, and aluminum foil was used as the metallic layer for D-band operation. The measured loss in window 3 is lower than the loss in windows 1 and 2, because with the increase in frequency, the Dcore/λ ratio increases as well. The lowest measured loss of the designed fiber was 25.6 dB/m at 0.145 THz, whereas the corresponding simulated loss was 6.6 dB/m. The discrepancies between the measured and simulated loss are primarily attributed to structural deformations of the fiber end faces. We have numerically analysed the impact of structural deformations and observed that they shift the transmission windows and introduce unexpected resonances in the regions of interest. The designed fiber exhibits the smallest dimensions and normalized core size (Dcore/λ = 1.91 @0.145 THz) among recently reported 3D-printed hollow-core fibers operating in the sub-THz regime, while maintaining competitive loss performance. In the next phase of this work, we will fabricate the non-uniform cladding oval-tube antiresonant HCF using an extrusion method. By shifting to extrusion, we aim to fabricate longer fiber lengths free from 3D-printing limits while simultaneously improving surface smoothness and reducing structural deformation.
| I am the presenting author | Yes |
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