Crystallite size Defects Doped tin oxides Emission spectroscopy Energy gap Eu doping Eu-doped tin oxide Linear and nonlinear optical properties Morphology Nonlinear optics Optical characterization Optical limiter Optical limiters Optical limiting properties Optical properties Oxide films Photoluminescence Semiconductor doping Spray pyrolysis Structural characterization Thin films Thin-films Tin oxide thin film Tin oxides