The absorption and emission spectra of Ga-La-S:O doped with Pr3+, and Ga-Ge-As-S chalcogenide glasses doped with Pr3+, Dy3+, Nd3+, Sm3+ and Ho3+ were experimentally investigated at room temperature and at T=4 K. Photoluminescence spectra were measured at low temperature (T=4 K) at excitation by He-Ne (λ=632.8 nm line) and Ar ion (INNOVA 306, λ=514.5 nm line) lasers working in CW regime, in order to observe simultaneously the narrow 4f-4f emission from rare-earth ions and the broad band luminescence of the host glass. In the transmission spectra of rare-earth doped glasses differs from that of the base glass. The major feature in low-temperature of photoluminescence spectra (PL) is the presence of the broad band luminescence of the host glass and relatively sharp 4f-4f radiative transitions due to the presence of rare-earth (RE3+) ions, that gives the direct evidence of the energy transfer between the host glass and respective RE3+ dopants.
Chalcogenide glasses based on arsenic sulfide (As2S3), arsenic selenide or telluride are known to exhibit high optical
nonlinearities which are necessary for advanced applications in telecommunications. Both, standard optical fibers and
microstructured fibers have been fabricated from chalcogenide glasses. In this paper we deal with As2S3 solid core fibers
and capillary fibers coated with a polymer jacket of UV acrylate. The guiding mechanism employing the reflection on
boundary of high-index glass (a refractive index of about 2.4) and hollow cavity (n=1) was confirmed by ray-optic
calculations.
Fibers were drawn from input As2S3 rods and tubes. The rods were prepared from extra pure arsenic and sulfur by their
melting in an evacuated ampoule. The tubes were prepared by using rotational melting technique in an evacuated
ampoule rotating at 1600 rpm. Rods and tubes were elongated into fibers by using a fiber drawing facilities for
preparation of optical fibers from soft optical glasses. Temperatures in a range 300-400 °C and drawing velocities of
about 0.1 m/s were used. Fibers were prepared either without any polymeric jacket or they were provided by a jacket of
UV acrylate (n ∼ 1.5). Fibers with diameters from 0.2 to 0.4 mm were fabricated.
Dimensions of prepared fibers were measured by optical microscopy without prior polishing. Transmission properties of
prepared fibers were characterized by measuring angular distributions of output power at the wavelength of 670 nm.
Optical losses of fibers exceeding 2 dB/m were determined by using the cut back method.
We report about properties of epoxy novolak resin polymer doped with dysprosium ions. The polymer layers were
fabricated by spin-coating onto silicon substrates, or pouring epoxy novolak resin solution into bottomless molds placed
on a quartz substrate and leaving them to dry. Rather strong bands around 3366 cm-1 in the infrared spectra indicated
presence of the O-H groups. Absorption measurements were done in the spectral range from 300 nm to 3000 nm and
showed six strong bands at 758 nm (6F3/2), 807 nm (6F5/2), 906 nm (6F7/2), 1100 nm (6F9/2), 1280 nm (6F11/2) and 1685 nm
(6H11/2) corresponding to Dy3+ ions. Optical band gap Eg was determined from the absorption coefficient values using
Tauc's procedure, i.e., from the relationship αhv = A(hv - Eg)2 and the obtained values varied from 3.489 eV to 3.539 eV
depending on the amount of dysprosium ions involved in the samples. Photoluminescence spectra around 1300 nm were
investigated by using excitation of He-Ne laser (632.8 nm) and two semiconductor lasers (980 nm and 827 nm).
We report about properties of Gallium Nitride layers doped by Erbium and Erbium/Ytterbium ions. The GaN layers were fabricated by Metal Organic Chemical Vapor Deposition on sapphire substrate, and Er3+ and Yb3+ ions were incorporated into the deposited layers by using ion implantation. After the implantation the samples were annealed in nitrogen atmosphere. The structures of the GaN samples were examined by the X-Ray Diffraction analysis; composition of the samples was measured by Rutherford Backscattering Spectroscopy and Elastic Recoil Detection Analysis. The GaN layers had single crystalline hexagonal wurtzite structure and content of Er3+ and Er3+\Yb3+ ranged from 0.05 to 3.38 at. %. The photoluminescence measurement was carried out at excitation of λex = 632.8 nm (temperature 4 K) and λex = 980 nm (room temperature). Photoluminescence spectra taken at 4 K showed typical erbium 4I13/2→4I15/2 emission bands. Some of our samples exhibited the desired emission even at the room temperature, which indicated that the samples were of a good quality what concerned their crystallographic homogeneity, as well as distribution and appropriate concentration of the Er3+ and Yb3+.
Erbium (Er3+) and Ytterbium (Yb3+) ions doped Gallium Nitride (GaN) layers were deposited by RF magnetron sputtering. Deposition was carried out in Ar + N2 gas mixture using Ga and Ga2O3 target as the source of Gallium. For the erbium and ytterbium doping, the Er2O3, Yb2O3 pellets, or Er and Yb powder were laid on the top of the Ga2O3 target. The GaN layers were deposited on silicon and Corning glass substrates. The properties of the GaN layers were investigated by using X-ray diffraction, Raman spectroscopy, absorption spectra and photoluminescence spectra. Prism coupling mode spectroscopy was used to measure the waveguiding properties. The composition of the fabricated samples was determined by using nuclear chemical analysis as Rutherford Backscattering Spectroscopy (RBS) and Elastic Recoil Detection Analysis (ERDA). The results of the experiments were evaluated in terms of the relations between the technology approaches and the composition and luminescence properties of the fabricated thin films. Up to now the best results, which can be utilized for a structure operating at 1550 nm (when pumped at 980 nm), were obtained when using (erbium plus ytterbium) metallic powder and Corning glass as the substrate for the deposition.
Diagnosis established by means of fluorescence spectroscopy is currently used in the field of urology and bronchology. Its major advantage is that it allows the diagnosis of epithelial dysplasia or malignant proliferation even if routine diagnostic endoscopy fails to reveal any macroscopic changes.
The authors present results of their observations that deal with fluorescence diagnosis of colorectal carcinoma. They examined the wet microscopic mounts of healthy colon mucosa and compared them to that prepared from colon mucosa affected by adenocarcinoma. The diagnosis of adenocarcinoma was verified by using clinical and histology means.
Fluorescence spectra of tissue samples, excited by means of 488 and 514.5 nm lines of Ar ion laser and/or by He-Ne laser line 632.8 nm, have been studied. This study demonstrated differences in both the spectral shape and in the signal intensity (at unchanged spectral shape) of photoluminescence spectra emitted from tissue affected by adenocarcinoma as compared to that of healthy colon mucosa. The results encourage us to continue the study aimed at development of the diagnostic system usable in the clinical practice.
Chalcogenide glasses - Ge25Ga10S65 , Ge25Ga5As5S65 , As2S3 , As2S2Se , As25e3 — have been synthesized and doped with ions of rare earth RE3 , in the concentration range of 500 to 6000 wt.ppm. Special processing makes possible to reduce the hydroxyle content and to incorporate rare earth ions without phase separation. Various physical measurements, including photoluminescence have been implemented. Main observations and results may be summurized as follows: -OHgroup concentration could be lowered below 5x105 mol.% in pure chalcogenide glasses - Rare earth ions are introduced into sulfide glasses at concentrations ranging from 500 to 6000.ppm. Homogeneous and clear samples are obtained up to 3000wt.ppm Pr3+. - Clusters and defects are observed when RE and OH concentrations increases,. -Abackground photoluminescence in based glasses and it depends on temperature.
Chalcogenide glasses based on suplhides and selenides are very promising materials for various photonic applications, particularly for applications in medicine. Most of current optical fibers have been developed form ultrapure silica. While silica glasses are suitable for optical components in telecommunications they exhibit high losses beyond 2 micrometers - a wavelength range important for clinical practice. Thus special glass materials 9from which fibers could be drawn) should be developed for optical power transmission beyond 2 micrometers . The investigation and preparation of vitreous materials that include sulphide, selenide and selenide- tellurite glass systems together with fluoride and heavy metal oxide glasses on the base of ZrF4, HfF4 and GeO2, TeO2, PbO, respectively are being pursued in our laboratory. This research is aimed at the development of both passive and active (rare-earth doped) optical fibers. In this contribution we concentrate on the doping of chalcogenide glasses by rare earth elements (Er, Pr, Nd). Although the major role of these glasses is assumed in the development of laser power delivery systems for applications in surgery, dentistry, dermatology and ophthalmology, they can equally be used for the diagnostics of human tissues. An example of colon tissue autofluorescence will be given.
Sulphide glasses of GeGaS and GeGaAsS systems doped with rare earth ions are promising materials for various photonic applications. Because the solubility of rare earth elements ins influenced by the purity of host glass, namely by OH group concentration, the attention has been paid to the preparation of highly pure and homogeneous undoped and rare earth doped glasses. Particularly the systems Ge0.25Ga0.1-xS0.65Prx and Ge0.25Ga0.05- xAs0.05S0.65Prx with x equals 500, 1000, 3000, 6000 wt. ppm have been prepared. Synthesized materials system have been characterized by Raman and low-temperature photoluminescence spectroscopies. The optical Pr concentration has been found to be around 1000 wt.ppm. The appearance of temperature induced radiative transitions have been observed on GeGaS:Er samples.
General chemical compositions of prepared glasses with low OH group concentrations are Ge0.25Ga0.10S0.65, Ge0.25Ga0.05As0.05S0.65, (TeO2)x - (PbCl2)1-x with x equals 0.4 to 0.6 and (TeO2)x - (ZnO)1-x with x equals 0.75 to 0.80. Samples doped with 500 to 12000 ppm rare earth in weight were prepared. Rare earth doped glasses are homogeneous when RE concentration is less than 3000 ppm. Heterogeneous inclusions arise beyond 1000 ppm RE when doping is made with chloride or oxide. Electron microscopy, absorption and fluorescence measurements have been made. YAG:Nd. Ar, He-Ne lasers were used for excitation of photoluminescence. The color and optic quality of the tellurite glasses depend on crucible materials. Rare earth doping results in visible defects or inhomogeneities when concentration is larger than 1000 ppm. The chemical composition and the optical absorption of doped and undoped samples was examined. Fluorescence intensity of Pr and Dy is smaller in these HMO glasses than in the sulfide glasses, which results from higher phonon energy and higher OH concentration. Further development is required for future applications.
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