Tunable emission and excited state absorption induced optical limiting in Tb2(MoO4)3: Sm3+/Eu3+ nanophosphors

Abstract Photoluminescence properties and optical limiting behavior of pure and Sm 3+ /Eu 3+ doped Tb 2 (MoO 4 ) 3 nanophosphors are investigated. The prepared nanophosphors exhibit excellent emission when excited by UV light. Color-tunable emissions in Tb 2−x Sm x (MoO 4 ) 3 and Tb 2−x Eu x (MoO 4 ) 3 are realized by employing different excitation wavelengths or by controlling the doping concentration of Sm 3+ and Eu 3+ . Luminescence quantum yield and CIE chromatic coordinates of the prepared phosphors were also presented. Optical limiting properties of the samples are investigated by open aperture Z-scan technique using 5 ns laser pulses at 532 nm. Numerical fitting of the measured Z-scan data to the relevant nonlinear transmission equations reveals that the nonlinear absorption is arising from strong excited state absorption, along with weak absorption saturation and it is found that the optical nonlinearity of Tb 2 (MoO 4 ) 3 increases with Sm 3+ /Eu 3+ doping. Parameters such as saturation fluence, excited state absorption cross section and ground state absorption cross section of the samples have been determined numerically, from which the figure of merit for nonlinear absorption is calculated. The excited state absorption cross-section of the samples is found to be one order of magnitude higher than that of the ground state absorption cross-section, indicating strong reverse saturable absorption. These results indicate that Sm 3+ /Eu 3+ doped Tb 2 (MoO 4 ) 3 nanophosphors are efficient media for UV/n-UV pumped LEDs, and are also potential candidates for designing efficient optical limiting devices for the protection of human eyes and sensitive optical detectors from harmful laser radiation.