Refractive index structures in polymers

Abstract

Refractive index structuring of poly(methyl methacrylate) (PMMA) by femtosecond (fs) laser irradiation is discussed, including writing conditions defined by wavelength, pulse duration, and associated photochemistry. The aim is to determine optimal conditions for refractive index modification, Δn without doping for photosensitivity. The work presented here forms a generic methodology for other polymers. Nanostructuring using holographic optics and precise control of beam parameters has versatile application for three-dimensional (3D) photonic devices. Self-focusing and filamentation at various depths below the surface of bulk PMMA are discussed together with parallel processing using a spatial light modulator. Applications of refractive index structures in polymers include microfluidics, lab-on-a-chip, organic optoelectronic devices, and gratings in polymer optical fibres.