Waveguide Amplifiers and Lasers Based on FASnI3 Perovskite Thin Films

In this work, high-quality polycrystalline formamidinium tin iodide (FASnI 3 ) perovskite thin films are integrated into rigid and flexible substrates to demonstrate optical amplification and lasing. With an appropriate low-temperature treatment and polymethylmethacrylate (PMMA) clapping, the FASnI 3 films exhibited remarkable stability and an efficient emission at room temperature. These layers were properly incorporated on rigid (SiO 2 /Si) and a flexible polyethylene terephthalate (PET) substrate and cladded by a polymethylmethacrylate (PMMA) thin film. The structures conformed to a planar waveguide whose geometrical parameters (i.e. thicknesses of the films) are carefully chosen to demonstrate the generation of amplified spontaneous emission and random lasing modes with extremely low thresholds, 100 nJ/cm ² and 1 µJ/cm ² on rigid and flexible substrates, respectively. In a second device, the FASnI 3 films are incorporated as an active medium in a distributed Bragg reflector properly designed to achieve optical resonance at the ASE wavelength. This architecture conforms to an optical cavity able to demonstrate the generation of lasing action with peaks narrower than 1 nm. The proposed devices represent an important step towards the development of future cheap and green photonic technology based on Sn perovskites.