Three- and two-photon upconversion luminescence switching in Tm3+/Yb3+-codoped sodium niobate nanophosphor

Abstract

Intense infrared-to-visible upconversion (UC) emission in Tm 3þ ∕Yb 3þ -codoped sodium niobate (NaNbO 3 ) nanocrystals under resonant excitation at 976 nm is presented. The results showed that by increasing the pump power/intensity, a strong reduction is observed at the 800∕480 nm emitted intensity ratio, characterizing what can be denominated as laser pump power-induced color tunability or luminescent switching. The physical origin is discussed with a focus on tailoring of luminescent switchers to operate at a large pump power range and, indeed, it is intrinsically associated with the competition of the two-and three-photon UC processes and with highly efficient UC emissions in the investigated material. The effect of Yb 3þ -ion concentration along with the theoretical aspects on luminescence switching has been investigated. The results obtained here could be useful in the field of sensors and networks for optical processing and optical communications.

Ultraviolet and White Light Emissions from Multiphoton Upconversion Transitions in Yb/Tm/Ho Codoped Cubic Zirconia Single Crystals Excited by NIR

“…The 3 F 4 state is then excited to the 3 F 2,3 state through excited state absorption (ESA), which then either decays to the 3 H 6 ground state with the emission of red light at 677 nm or relaxes to the 3 H 4 state through a phonon-assisted nonradiative transition process. The 3 H 4 state either decays back to the 3 H 6 ground state with the emission of near-infrared light at 780 nm or is excited to the 1 G 4 state through a second ESA process, after which the 1 G 4 state decays to the 3 H 6 ground state with the emission of blue light at 486 nm, or decays to the 3 F 4 state with the emission of red light at 660 nm. , The intensities of ultraviolet emission peaks at 308/359/376 nm are dependent on the populations of the Tm 3+ : 1 D 2 and the 1 I 6 states. For the population of the 1 D 2 energy state, the energy difference between the Tm 3+ : 1 G 4 and 1 D 2 state calculated from the absorption spectra is 6.46 × 10 3 cm –1 .…”

Recent advances in lanthanide spectroscopy in Brazil

“…Other investigations on the luminescence properties of lanthanide-based systems with NPs, nanorods or systems assembled using sol-gel techniques have been reported in the literature [17,22,27,33,34,38,40,43,45,49,50,60,61,67,73,78,82,88,93,107,[127][128][129]133,136,140,142,143,149,163,[169][170][171]176,178,201,211,212,214,[235][236][237][238][239][240][241][242][243][244][245]…”

NaGdF4:Dy3+ nanocrystals: new insights into optical properties and energy transfer processes

“…In recent decades, the interest of scientists in phosphor materials with sizes ranging from nanometers to micrometers has been increasing due to their abundant applications in fields such as lighting, color displays, medicine, solid laser, light emitting diodes, luminescence switching, and solar cells. [1][2][3][4][5][6][7][8] The luminescence of these materials is usually based on the emission of trivalent rare earth (RE 3+ ) ions in the vis or IR regions under excitation of VUV, UV, or vis irradiations. It is reported that fluoride NCs based on MLnF 4 (M = Li, K, Na, and Ln = La-Lu) compounds are the ideal host matrices for the luminescence of RE 3+ ions due to their low phonon energy.…”