Yu, Shuoying, et al. Optical and Quantum Electronics, 2021, 53, 1-12.
A dual-core hollow waveguide based on polytetrafluoroethylene (PTFE) and ultraviolet (UV) gel has been successfully prepared. PTFE and UV gel exhibit low refractive index and transparency in a wide wavelength range. The obtained dual-core hollow waveguide has good bending performance, and the transmission loss increases from 1.63 dB/m to 3.22 dB/m as the bending angle increases from 0° to 90°.
Preparation process of PTFE-based dual-core waveguide
· Using a standard wet chemistry technique, a typical Ag/AgI hollow fiber was created through a process involving sensitization, silvering, and iodization.
· Through a simple heat treatment process, the PTFE tube shrinks and then transforms into a low-refractive-index polymer layer on the outside of the quartz glass tube. The Ag/AgI fiber was then placed inside PTFE-coated silica glass tubing to construct a dual-core hollow waveguide.
· Prior to insertion, the tubing was filled with UV gel, which formed a liquid layer on the outer surface of the fiber as it passed through a container of UV gel. The ends of the fiber were sealed to prevent gel contamination in the hollow core.
· With a stepper motor driver, the fiber was slowly and gently inserted into the tubing at a speed of approximately 5 mm/s, ensuring no air bubbles were trapped in the gel gap between the fibers.
· The UV gel within the fiber was cured using a 364 nm UV lamp directed at one end of the sample for 3-5 minutes. Once cured, the ends of the fiber were trimmed to remove any seal material and complete the fabrication process.
