Nonlinear emission in CsPbBr3 decorated metasurfaces

Halide perovskites are extremely interesting semiconductors for innovation in optoelectronics and photovoltaics. In particular, they are efficient emitters of both incoherent and coherent light and, therefore, of interest as active materials in lasers, light amplification systems (resonators and waveguides), and other photonic devices. Here, we present a set of experimental results concerning nonlinear effects in the radiative emission of CsPbBr3 films deposited by spin-coating on a silicon substrate and on metasurfaces realized by microspheres having a core of SiO2 and a shell of TiO2 (T-Rex). We evidence the presence of amplified spontaneous emission which, depending on the sample structure, shows different behavior as a function of the excitation power. In particular, we distinguish between two processes: light amplification by randomly arranged emitters and amplification by a quite ordered distribution of nanocrystals around a resonator.