Designing Optical Glasses and Glass-Ceramics for Mid-Infrared Sensing Application
Kuusela, Luukas (2020)
2020
Degree Programme in Science and Engineering, MSc (Tech)
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2020-06-18
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202006075945
https://urn.fi/URN:NBN:fi:tuni-202006075945
Tiivistelmä
The purpose of this thesis was to design new optical glasses and glass-ceramics that can be deposited to thin films to be used as a mid-infrared light source and waveguiding layer for sensing application. Thus, the goal was to develop new glass-based materials with strong emission at 2.7 µm, corresponding to the 4I11/2 → 4I13/2 transition of Er3+ under 980 nm laser excitation.
Erbium doped germanate glasses with the composition (1-x/100)*(64.6GeO2-10Ga2O3-11.4BaO-9Na2O)-xEr2O3-5MO with MO=Al2O3, TiO2, Y2O3 and ZnO and with x=0, 1 and 2.5 (in mol%) were prepared by the melt-quenching technique. The analysis of the IR spectra showed a high OH content in the glasses which is detrimental for MIR emission. Indeed, the OH groups in glass lead to a non-radiative relaxation route to quench the 2.7 µm emission. 2.7 µm emission was detected from all of the 2.5 mol% erbium containing glasses. The glass-ceramics were obtained by heat treating the glasses at T_g+20°C for 17 h to create the nuclei followed by a heat treatment at T_p for 1h and 6h for the growth of the nuclei into crystals. All of the glasses crystallized upon heat treatment. The crystallization mechanism was identified to be surface crystallization. The heat treatment increased the intensity of the emission of the Y containing glasses at 1.5 and 2.7 µm due to the crystalline field effect as evidenced by the sharp peaks in the emission bands. The Y containing glass had the most connected glass network, lowest OH content and highest 2.7 µm emission.
Electron beam physical vapor deposition was used to deposit thin film from the newly developed glass with MO=ZnO..The composition of the thin film was studied by X-ray photoelectron spectroscopy. Only Ge and Na were detected in the film. The original target and the deposited film were deemed unsuitable for the application, more deposition trials are needed to achieve thin films with similar luminescent properties as the target.
Erbium doped germanate glasses with the composition (1-x/100)*(64.6GeO2-10Ga2O3-11.4BaO-9Na2O)-xEr2O3-5MO with MO=Al2O3, TiO2, Y2O3 and ZnO and with x=0, 1 and 2.5 (in mol%) were prepared by the melt-quenching technique. The analysis of the IR spectra showed a high OH content in the glasses which is detrimental for MIR emission. Indeed, the OH groups in glass lead to a non-radiative relaxation route to quench the 2.7 µm emission. 2.7 µm emission was detected from all of the 2.5 mol% erbium containing glasses. The glass-ceramics were obtained by heat treating the glasses at T_g+20°C for 17 h to create the nuclei followed by a heat treatment at T_p for 1h and 6h for the growth of the nuclei into crystals. All of the glasses crystallized upon heat treatment. The crystallization mechanism was identified to be surface crystallization. The heat treatment increased the intensity of the emission of the Y containing glasses at 1.5 and 2.7 µm due to the crystalline field effect as evidenced by the sharp peaks in the emission bands. The Y containing glass had the most connected glass network, lowest OH content and highest 2.7 µm emission.
Electron beam physical vapor deposition was used to deposit thin film from the newly developed glass with MO=ZnO..The composition of the thin film was studied by X-ray photoelectron spectroscopy. Only Ge and Na were detected in the film. The original target and the deposited film were deemed unsuitable for the application, more deposition trials are needed to achieve thin films with similar luminescent properties as the target.