1.5 μm photoluminescence and upconversion photoluminescence in GeGaAsS:Er chalcogenide glass

Abstract

The paper reports on ≈1.5 μm Stokes photoluminescence (PL) emission and upconversion photoluminescence (UCPL) emission in the visible and near-infrared spectral region in Er3+-doped Ge25Ga8As2S65 chalcogenide glasses at pumping wavelengths of 980 and 1550 nm. The ≈1.5 μm PL emission spectra are broadened with increasing concentration of Er ions which is discussed in terms of radiation trapping and UCPL dynamics affecting the Er3+: 4I13/2 level lifetime. The UCPL emission was observed at ≈530, ≈550, ≈660, ≈810 and ≈990 nm and its overall intensity as well as red-to-green UCPL emission intensity ratio increases with increasing Er concentration. To explore the UCPL dynamics we measured double logarithmic dependency of green (≈550 nm) and red (≈660 nm) UCPL emission versus pump power at pumping wavelength of 975 nm. Moreover, we measured quadrature frequency resolved spectroscopy (QFRS) on green UCPL emission (≈550 nm) using 975 nm pumping wavelength and various excitation powers. The QFRS spectra on green UCPL were analyzed in term of QFRS transfer function for three-level model from which we deduced energy transfer upconversion rate w11 (s−1) originating from Er3+: 4I11/2, 4I11/2→4F7/2, 4I15/2 transitions.

Deep red upconversion photoluminescence in Er3+‐doped Yb3Ga5O12 nanocrystalline garnet

“…As a result, the presence of the CR1 and CR2 processes in combination with the ESA2+ETU2 in heavily Er 3+ -doped solids decreases the green-to-red UCPL emission intensity ratio. 55,70 However, it should be noted that, even in the highly Er 3+ -doped samples, the green and red UCPL emission intensities do not differ so significantly as in the Er 3+ and heavily Yb 3+ -co-doped samples. 33,34 For example, the green UCPL emission dominates over the red UCPL emission in the 1 at.% Er 3+ -doped Gd 3 Ga 5 O 12 garnet 27 or 1 at.% Er 3+ -doped nanocrystalline ZrO 2 31 at the pumping wavelength of ≈980 nm.…”

“…Compared to that, the increase of the Er 3+ ion concentration in a solid shortens the interatomic distance between the adjacent Er 3+ ions, and it results in the decrease of the greento-red UCPL emission intensity ratio. [49][50][51][52][53][54][55][56] This suggests that additional UCPL pathways to the above-mentioned GSA/ESA1 and/or GSA/ESA2 mechanism populating the Er 3+ : 4 F 9/2 level or bypassing the population at the Er 3+ : 4 [51][52][53][54][55][56][67][68][69] Therefore, after the GSA/(ESA1+ETU1) process, the Er 3+ : 4 F 9/2 energy level may be populated via the population of the Er 3+ : 4 I 13/2 energy level, for example, by the CR2 process followed by ESA2 and/or ETU2 or directly via the CR1 process (see Figure 6). Both the CR1 and CR2 processes bypass the population at the Er 3+ : 4 F 7/2 / 2 H 11/2 / 4 S 3/2 energy levels responsible for the green UCPL emission.…”

“…[51][52][53] Such decrease may be explained by the change of the UCPL dynamics from the lightly Er 3+ -doped to the moderate/heavily Er 3+ -doped hosts. 54,55 At the low Er 3+ doping level, the UCPL emission is a result of the occurrence of the GSA Er 3+ : 4 I 15/2 → 4 I 11/2 followed by the excited state absorption (ESA), that is, Er 3+ : 4 I 11/2 → 4 F 7/2 (ESA1) or Er 3+ : 4 I 13/2 → 4 F 9/2 (ESA2) [54][55][56] as is presented in Figure 6.…”

“…At the low Er 3+ and high Yb 3+ doping levels of the Er 3+ /Yb 3+co-doped samples, the ETU and CR processes between Er 3+ ions may be omitted due to the longer interatomic distances between the adjacent Er 3+ ions. [51][52][53][54][55][56] However, the interatomic distance between the adjacent Er 3+ and the Yb 3+ ions in lightly Er 3+ -doped and heavily Yb 3+ -codoped hosts, such as Yb 14.99 Er 0.01 Ga 25 O 60 garnet, may be sufficiently short making the Yb 3+ ↔ Er 3+ ETU processes probable. 33,34 Moreover, the absorption cross-section of the Yb 3+ : 2 F 7/2 → 2 F 5/2 transitions are notably larger than that of the Er 3+ : 4 I 15/2 → 4 I 11/2 transitions but in resonance.…”

Intense Anti‐Stokes Emission from Erbium Ions in Gallium Lanthanum Sulphide–Oxide Glass in the Visible Spectral Range

“…[11,12,[19][20][21][22][23][24][25]). The use of other wavelengths for pumping is less frequent ( [26][27][28][29] and references therein) but could provide new insight into spectroscopy of these materials. In the present research, we use a semiconductor laser diode operating at 808 nm with a spectral half width of %3 nm.…”