Er3+-doped fluorotellurite thin film glasses with improved photoluminescence emission at 1.53 µm

Abstract

Transparent oxyfluoride tellurite thin film glasses have been produced at room temperature by pulsed laser deposition in O 2 atmosphere from an Er-doped TeO 2 -ZnOZnF 2 bulk glass. Thin film glasses present high refractive index (n≥ 1.95) and good transparency (T≥ 80%) in the visible (λ> 400nm) and near infrared range. However, their photoluminescence (PL) performance at 1.5 µm is poor. Thermal annealing at moderate temperatures (T≤ 315 ºC), well below glass crystallization, increases the PL 2 intensity by more than one order of magnitude as well as the PL lifetime up to τ≈ 3.3 ms. Film glasses present a larger fraction of TeO 3 trigonal pyramids than the bulk glass and a very large OH -content. The structure and composition of film glasses does not change upon annealing and thus the activation of the PL response is related to the improvement of the surface morphology and the significant decrease of their OHcontent.

Pulsed laser deposition of rare-earth-doped glasses: a step toward lightwave circuits

“…However, these film glasses present in most cases a poor PL performance; thus a post-deposition thermal treatment is required. 21 This is clearly seen in Fig. 4b, which shows the evolution of PL intensity at 1.53 μm for an Er-doped fluorotellurite film that underwent successive annealing steps at increasing temperatures (T ann ).…”

“…As-deposited films present a very strong absorbance (α M ≈ 1000 cm -1 ), which is much larger than the value measured for the bulk glass (α M ≈ 0.5 cm -1 ), not shown in the figure. This implies that the concentration of OHgroups (N OH~ 10 22 cm -3 ) is about 2 orders of magnitude larger than that of Er 3+ ions 21 and thus, Er 3+ ions are most likely surrounded by OHgroups, which completely quenches PL emission in the asdeposited films as it is shown in Fig. 4b.…”

“…The structural and optical characterization techniques are described in detail elsewhere. 19,20,21 Finally, steady-state PL measurements of Er-doped PNG and fluorotellurite glasses were performed at room temperature using a 980 nm excitation source (Ti-Sapphire laser or diode laser). The fluorescence emission (I PL ) at 1.5 μm was collected along the direction perpendicular to the film using a 0.25 m monochromator, coupled to an extended IR Hamamatsu R5509-72 photomultiplier and finally amplified by a standard lock-in technique.…”

“…The absorbance decreases from α M ≈ 1000 cm -1 to α M ≈ 160 cm -1 and the spectral position of the absorption peak shifts to lower wavenumbers upon annealing, which relates to the significant removal of free (≈ 3400 cm -1 ) and weakly bounded (≈ 2900 cm -1 ) OHgroups. 21,31 This is enough to reduce the N OH /N Er ratio down to ≈30, which increases the probability of Er 3+ radiative deexcitation as shown in Fig. 4b.…”

High Er3+ luminescent efficiency in Er-doped SiOx films containing amorphous Si nanodots

“…In recent years, the Er 3+ -based luminescence has been intensively studied due to 18 its attractive emission wavelength at 1.5 µm, which minimizes the attenuation and 19 dispersion in quartz optical fibers [1,2]. However, further implementation of such 20 materials requires efforts to enhance the transition efficiency of Er 3+ ions.…”