1：Experimental Design and Method Selection:

The study uses a computer model based on solving the quasi-stationary parabolic equation to simulate the formation of waveguiding structures in a photopolymerizable composition (PPC). The model incorporates equations for refractive index change due to polymerization and radiation propagation. Experimental validation is performed using an optical setup with lasers, fibres, and detectors to form and test polymeric connectors.

2：Sample Selection and Data Sources:

Samples include a multimode gradient fibre (core diameter 50 μm) and a single-mode stepped-index fibre SMF-28 (core diameter 8.2 μm). The PPC is based on oligo(carbonate methacrylate) (OCM-2) with added acetonitrile.

3：2 μm). The PPC is based on oligo(carbonate methacrylate) (OCM-2) with added acetonitrile. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment includes semiconductor laser modules (λ=0.63 μm, 5 mW), IR-laser module (λ=1.55 μm), photodetector PD-1180, micromanipulators, lenses, beam splitters, and a reactor for the PPC. Materials include OCM-2 oligomer, acetonitrile, and photoinitiating system.

4：63 μm, 5 mW), IR-laser module (λ=55 μm), photodetector PD-1180, micromanipulators, lenses, beam splitters, and a reactor for the PPC. Materials include OCM-2 oligomer, acetonitrile, and photoinitiating system. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Fibres are positioned with micromanipulators in the PPC-filled reactor. Lasers emit visible and IR radiation to form polymeric channels. The transfer coefficient is measured during and after polymerization. The process involves iterative exposure and curing with lateral light to solidify the structure.

5：Data Analysis Methods:

Data analysis involves calculating the light transfer coefficient using the module of the Pointing vector, and spectral absorption measurements are performed to assess transparency.