Infrared upconversion efficiency of electron-trapping thin film CaS:Eu, Sm

Infrared upconversion and optical storage thin film CaS:Eu, Sm was successfully developed by means of electron beam evaporation and radio frequency (rf) magnetron sputtering. Infrared upconversion efficiency of CaS:Eu, Sm thin films with different thickness was investigated by using the ultrashort infrared laser pulses with different FWHM. It was shown that upconversion efficiency of CaS: Eu, Sm thin film not only depends on the growth conditions and the post annealing process, but also has the exhaustion phenomenon. By means of measuring transmittance and spatial resolution of CaS:Eu, Sm thin film,the post annealing process was found out to promote grain growth which can significantly improve the upconversion efficiency of CaS:Eu, Sm thin film, though it has negative influence on transmittance and spatial resolution of CaS:Eu, Sm thin film.