Vis-NIR luminescence emission via energy-transfer in Tm3+/Er3+ and Tm3+/Nd3+ codoped glass under 1.319 µm excitation

Emission of visible and NIR frequency upconversion luminescence light mainly within the first biological window spectral region using excitation at 1319 nm in the second biological window in Tm3+/Er3+-codoped TeO2-based glass, is demonstrated. For Tm3+/Er3+-codoped tellurite glass samples, green(525, and 550 nm), red(660 nm) and NIR(980 nm) owing to erbium ions in addition to the main 800 nm signal originating from thulium ions is readily observed. Here, energy-transfer Tm3+[3F4]+Er3+[4I15/2]→Tm3+[3H6]+Er3+[4I9/2] producing the NIR emission, followed by excited-state absorption of 1.319 µm photons populating 2H11/2, 4S3/2, and 4F9/2 visible emitting levels. Erbium single-doped samples did not exhibited visible detectable emissions for excitation powers as high as 1.8 W of cw radiation at 1.319 µm. In Tm3+/Nd3+-codoped samples, energy-transfer from Tm3+ (3H6-3F4) to Nd3+ ions populates the 4F3/2 excited-state level producing NIR emission around 880 nm.