Three-photon excitation of an upconversion random laser in ZnO-on-Si nanostructured films

Abstract

We report the first observation, to our knowledge, of ultraviolet upconversion random laser (RL) emission from ZnO films excited by three near-infrared photons in the femtosecond regime. The nanostructured films of ZnO were fabricated on a silicon substrate using the Plasma Immersion Ion Implantation and Deposition method. The band-to-band excitation process led to RL emission with incoherent feedback, emitting light at ≈390  nm. RL emissions excited by one and two photons were also verified using the same pump geometry. The results are discussed and a comparison with previous studies is presented.