1.5-μm infrared excitation of visible luminescent in Y1−xErxF3 and Y1−x−yErxTmyF3 via resonant-energy transfer

Abstract

Intense visible emission in the red, green, and blue has been observed from infrared to visible multiphoton Y1−xErxF3 upconversion phosphors pumped with 1.5-μm radiation from InGaAsP-laser sources. With 0.01<x<0.2, the dominant emission is in the green corresponding to transitions from the 4S3/2 level of Er3+. The addition of Tm3+ in the 0.001–0.02 range preferentially quenches the emission from the higher-energy Er3+ levels resulting in a red visible emission originating on the Er3+ 4F9/2 level. The phosphors are useful visible monitors of focused 1.5-μm semiconductor laser and unfocused F-center laser radiation. The unexpectedly high brightness in the visible may be attributed to thermal equilibration, where the excitation is trapped in the higher lying states after each upconversion step.

Upconversion luminescence in Er3+-doped germanate-oxyfluoride and tellurium-germanate-oxyfluoride transparent glass-ceramics

“…The strong green emission of 4 S 3/2 -4 I 15/2 occurs at a low Er 3+ concentration in which the energy transfers between excited ions generally is not significant as demonstrated previously for a single ion concentration o0.5 at% [32]. Absorption of 800 nm photons raises Er 3+ ions from ground state to the 4 I 9/2 state, which undergoes multiphonon relaxation to its lower state of 4 high rate.…”

“…There are two basic upconversion mechanisms: excitedstate absorption and energy transfer between excited ions [3,32]. The strong green emission of 4 S 3/2 -4 I 15/2 occurs at a low Er 3+ concentration in which the energy transfers between excited ions generally is not significant as demonstrated previously for a single ion concentration o0.5 at% [32].…”

“…Our glass sample was doped with 0.2 mol% Er 2 O 3 , corresponding to an Er 3+ ion concentration of 0.4 at%. At this concentration of single doping, the energy transfer process is not significant [14,32]. However, for transparent glass-ceramic samples, the Er 3+ ions are mostly incorporated into b-PbF 2 nanocrystals.…”

Effects of Activator Ion Concentration on the Upconversion Processes in Er3+-Doped TeO2-ZnO Glass

“…The bright green emission of the 4 S 3/2 ! 4 I 15/2 transition occurs in the 0.4 at% Er 3+ -doped glass in which energy transfer between excited ions can be ignored [15,16]. Absorption of 797 nm photons raises Er 3+ ions from the ground state to the 4 I 9/2 level, which undergoes multiphonon relaxation to its lower level of 4 I 11/2 with a high efficiency.…”

Infrared to visible upconversion in Er3+-doped lead oxyfluorosilicate glasses

“…5 [15][16][17]. There are two basic upconversion mechanisms: excited state absorption and energy transfer between excited ions [18]. The green emission of 4 which the energy transfer between excited ions generally can be ignored as demonstrated previously for single ion concentration o0.5 at% [18].…”