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IR photoluminescence in Ag0:05Ga0:05Ge0:95S2-Er2S3 glasses
Abstract
The photoluminescence (PL) spectra of Ag0:05Ga0:05Ge0:95S2-Er2S3 glasses excited by a laser diode operating at 980 nm have been investigated. The broadening of the PL band of the glasses with increase in the Er content has been found, by calculating a full-width at half-maximum (FWHM) and the effective width Δλef. Inhomogeneities with dimensions of 6-7 μm have been disclosed in the glassy alloys; their concentration increases with the erbium content and influence the width of the PL spectra.
... That kind of compounds is especially promising for photoinduced nonlinear optics, which was shown in recent works678 and electron– phonon anharmonic interactions stimulated by external light play principal role for them. Introduction of erbium leads to changes in optical absorption spectra, reducing the intensity of luminescence related to defects in the host matrix [9], the emergence of intense photoluminescence bands associated with intra-4f shell transitions of the Er 3 þ91011, and also promotes the formation of heterogeneities in glasses111213. Since structure is a major factor that determines the totality of the physical properties of chalcogenide glasses, so the changes in absorption spectra as well as correlations between the intensities of luminescence maxima have to be associated with microstructure of the erbiumcontaining glassy alloys. ...
... We believe that the band with maximum at 765 nm was formed as a result of overlaying of two radiative transitions 4 F 7/2 -4 I 13/2 and 2 H 11/2 -4 I 13/2 , which are not divided in the UPL spectrum due to a small distance between the energy levels 4 F 7/2 and 2 H 11/2 and their large Stark splitting. It should be noted that the intensity of luminescence with maximum l max ¼1540 nm ( 4 I 13/2 -4 I 15/2 ) at excitation wavelength of 980 nm reaches the largest value in samples with 0.27 at% Er [12] with maximum concentration of LSD. This indicates a high concentration of Er 3 þ ions in the excited state 4 I 11/2 originated by transitions from higher energy states of erbium ions that are located in the increased concentration area near the LSD. ...
The absorption spectra and up-conversion luminescence of glassy alloys (100−X)Ag0.05Ga0.05Ge0.95S2–(X)Er2S3, where Х=0.42, 0.25, and 0.18 mol% (0.27; 0.16; and 0.12 at% Er, respectively) at excitation using diode laser with wavelength 980 nm in the range 450–1050 nm were investigated. We propose mechanism of emission in the glasses based on the model of intra-4f shell transitions in Er3+ ion. The influence of the formation of the structural units on the optical properties of the glasses using Raman spectroscopy that is important when designing the erbium-containing environments in laser technology was studied.
In this article, we present the investigations of temperature dependent luminescence for the Ag0.05Ga0.05Ge0.95S2-Er2S3 glass system. The possibility to use temperature dependences of the photoluminescence of synthesized glasses for thermo sensors is considered. It is shown that logarithm of ratio of the integrated photoluminescence intensities for 980 and 600 nm (ln (I980/I660)) emission bands possess excellent linear dependence of temperature. At the same time, the nonlinear optical effects of two-photon absorption show substantial divergence from the sublinear dependences. These phenomena provide an opportunity to utilize Ag0.05Ga0.05Ge0.95S2-Er2S3 glasses for the fabrication of highly sensitive temperature sensor devices.
The absorption and up-conversion photoluminescence spectra of alloys of the Ag0.05Ga0.05Ge0.95S2−x
Er2S3 system (100 − x), excited with 980-nm laser irradiation, where x = 0.42, 0.25, and 0.18 mol %, have been studied. Green, intensive red, and infrared luminescence, which is caused by electronic 2H
11/2 → 4I
15/2, 4F
9/2 → 4I
15/2, 4S
3/3 → 4I
13/2 transitions in Er3+ ions, respectively, and connected with two photon up-conversion processes was recorded in all samples. The changes in the intensities of glassy alloys of radiation bands with different erbium contents and the influence of large structure defects on the processes of the occupation and the devastation of the energetic levels of erbium ions.
We have studied the thermal stability, in terms of the glass transition and crystallization, of (GeS2)75(Ga2S 3)25 glasses doped with high amounts of Er 2S3 (1.8 to 2.4 mol. %). These bulk glasses were synthesized from the sulphides of Ge, Ga and Er by conventional rapid quenching of the melts in ice-water. The Er3+ photoluminescence spectrum is a broad emission band at ∼1540 nm. The PL lineshape does not show any dependence on the Er3+ content. The PL decay times are in the 1.13 -1.55 ms range, and decrease with the rare earth content.
The photoluminescence (PL) efficiency of (GeS2) 80(Ga2S3)20 glasses doped with 0.17, 0.35 and 1.05 at % Er has been investigated. The PL has been excited by laser diodes operating at 982 and 532 nm. These wavelengths correspond to direct excitation of 4I15/2 → 4I11/2 transitions in Er3+ ions and to absorption in the host material, respectively. The PL band is presented as a sum of four Gaussian sub-bands. For all compositions, the PL band excited at 532 nm has been found to be narrower than that excited at 982 nm. The effect of broadening can be attributed to the development of broad Gaussian sub-bands centered at 1553 and 1600 nm, with the simultaneous reduction of sharp band centered at 1540 nm.
Chalcogenide Er-doped
(GeS2)75(Ga2S3)25
glasses have been characterized by some photoluminescence (PL) and
thermal parameters with a view to possible optoelectronic applications.
The emission spectra at ˜1540 nm under excitation with 1064 nm
light of heavily doped samples (1.05, 1.22 and 1.39 at% Er) have been
studied. The temperatures of glass transition and crystallization, as
well as the kinetics of crystallization for the un-doped and most doped
samples, have been determined by differential thermal analysis (DTA).
The optical properties of Er-doped Ge–Ga–Se glasses prepared by melt quenching techniques have been investigated. They were doped using Er2S3 and were stable as shown by temperature modulated differential scanning calorimetry. The influence of doping with Er on the photoluminescence, optical absorption and structural properties of Ge–Ga–Se glasses has been investigated and the strong correlation between the Er and Ga concentrations (CEr and CGa) and the properties of these glasses has been revealed. High CGa/CEr>10 ensures the homogeneous distribution of Er in host volume. Low CGa/CEr<3 leads to formation of chemical clusters found in the form of Er enriched crystalline inclusions. Intermediate region 3<CGa/CEr<10 is characterized by the formation of “physical clusters” or “clusters of interaction” where the Er ions are not connected chemically but the energy can effectively migrate form one ion to another.
We have studied the absorption and photoluminescence (PL) of (GeS2)80(Ga2S3)20 glasses doped with 0.17, 0.35 and 1.05at.% Er. The sharp bands centered at around 660, 810, 980 and 1540nm in the absorption spectra can be associated with intra 4f-shell transitions in Er3+ ions from 4I15/2 level to 4F9/2, 4I9/2, 4I11/2 and 4I13/2 levels, respectively. It has been observed that the absorption edge shifts towards lower energies with increasing Er concentration. A decrease in the absorption coefficient in the range of weak absorption, as well as the host luminescence in more heavily doped samples has been established, which may be associated with less native defects in the glassy structure. The role of excitation wavelength (λex) on the PL emission band at 1540nm using different Er3+-doping level has been evaluated. It has been found that the total PL band remains almost the same under direct excitation of Er3+ ions (at λex=644, 770 and 982nm), while it becomes narrower under the host excitation (at λex=532nm).