Random Lasing in Novel Dye-Doped White Paints with Shape Memory

Abstract

Although enormous advances are accomplished using shape memory polymers (SMPs) and their derived composites, the application of these media in optics and photonics is still restricted to a few systems. The present work addresses the fabrication and characterization of novel composites based on polydiolcitrates doped with titania nanoparticles, aiming at expanding the capabilities of the original elastomer. They constitute advanced photonic white paints, which incorporate the shape memory effect as an additional functionality. In these materials, light propagation is diffusive and it is possible to tailor its transport mean free path by acting on the titania fillers concentration. Optical gain is introduced by additionally doping the composites with organic dyes. This allows the shape recovery process to be monitored by luminescence and, conversely, the composites can perform as configurable shape active media. Their application in nonresonant feedback random lasers is demonstrated by systematic photoluminescence studies. The threshold for stimulated emission is shown to depend on both the fillers and dye concentrations. The so-obtained multifunctional composites are promising candidates for establishing synergies between applications from the domain of SMPs with those typically restricted to random photonic media, leading to novel self-reporting sensors/actuators or responsive illumination devices, for example.