Gel effects on the fabrication of gradient refractive index plastic rods via energy-controlled polymerization

A UV energy-controlled exposure process for the fabrication of gradient refractive index lenses was developed. In the proposed method, a V-shaped gel zone was formed in the reaction tube to prevent the formation of bubbles in the polymer matrix after photo-induced polymerization. Gel effects on the fabrication and properties of GRIN polymer rods were clarified, and the effect of concentrations of diphenyl sulfide, poly(methyl methacrylate) and photoinitiator on the optical properties of the rod lenses were investigated. A convenient method for the fabrication of gradient refractive index (GRIN) lenses via a UV energy-controlled process using a sloped UV lamp is described, and theoretically available equipment similar to the sloped UV-controlled polymerization system is also proposed.

Graphical abstractControlled energy photopolymerization was achieved using a sloped UV lamp. During UV polymerization, a V-shaped gel distribution region was formed in the reaction tube, and a significant energy-controlled effect on the fabrication and properties of GRIN rods was observed. Moreover, bubble-free GRIN rod lenses were successfully fabricated using the aforementioned equipment. The photo on the left shows the three dimensional refractive index distribution of a GRIN lens, and the photo on the right shows a real image transmission through a GRIN lens fabricated in the current investigation.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We develop a UV energy-controlled exposure process for the fabrication of gradient refractive index lenses. In the proposed method, a V-shaped gel zone was formed in the reaction tube to prevent the formation of bubbles in the polymer matrix after photo-induced polymerization. ► We examine gel effects on the fabrication and properties of GRIN polymer rods, as well as the effect of concentrations of monomers and photoinitiator on the optical properties of the rod lenses. ► Depending on the pitch of gradient refractive index (GRIN) lenses both real and virtual images can be observed.