Modeling the dynamic optical gain in a 3D printed waveguide due to polymer swelling

A theoretical model is developed to study the dynamic gain in the transmitted optical power through a 3D printed photopolymer waveguide. The given model shows that the solvent molecules diffused in the photopolymer and develops a swelling layer which acts as cladding. Formation of the cladding layer results in reduction of surface scattering losses and increase in the optical power. A methacrylate-based photopolymer waveguide is 3D printed using stereolithography as a single-step fabrication technique. Two solvents vapor: methanol and ethanol were tested with the given waveguide. An increase in the transmitted optical power is experimentally recorded and compared with the theoretical results to verify our model. This information is significant for fabricating integrated optical devices for sensing applications using photopolymers.