All-Plastic Organic Lasers with Top-Layer Polymeric Resonators: Tunable Emission through Bending and Application to Refractive Index Sensing

All-plastic thin-film organic lasers, in which all the layers comprising the device (active medium, resonator and substrate) are of polymeric nature, are very interesting because they offer the possibility to tune the emission laser wavelength through mechanical deformation (bending). Here, we report all-plastic distributed feedback (DFB) lasers based on top-layer dichromated gelatin resonators (one-dimensional gratings), active layers of polystyrene doped with perylene orange and substrates of cellulose acetate (CA), showing a successful laser performance, comparable to devices based on fused silica substrates. Remarkably, the emission wavelength of the prepared lasers can be tuned by approximately 10 nm through mechanical deformation (bending) thanks to the polymeric nature of all the layers involved in the device. This tuning is primarily due to changes in the grating period, while the layer thickness remains constant. The potential of the devices for refractive index sensing is also demonstrated. These findings highlight the potential of flexible top-layer resonator DFB lasers for applications requiring adjustable emission wavelengths, such as portable or adaptive optical systems. Additionally, the use of CA substrates and simple fabrication processes make these devices cost effective and easy to produce, opening the door to scalable and low-cost production for various optical applications.