Characterization of Composite Fibers
Vakkada Ramachandran, Arjun (2025)
2025
Master's Programme in Photonics Technologies
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
Hyväksymispäivämäärä
2025-10-06
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202510019634
https://urn.fi/URN:NBN:fi:tuni-202510019634
Tiivistelmä
The principal aim of this thesis was to characterize composite optical fibers using both laser diode and white light excitation, with the goal of analysing their transmission, loss, and emission properties.
Three distinct fiber types were investigated starting with Tm3+, Yb3+ codoped tellurite glass fibers prepared with the green persistent luminescent SrAl2O4:Eu2+, Dy3+ particles so that the fiber emits long lasting green light after near-infrared (NIR) charging. The second fiber was a bioactive glass-based fiber prepared with red upconversion crystals, Y2Ti2O7: Er3+ (28 mol%) for potential local drug release applications by converting the NIR light into red light. The third fiber was a phosphate glass-based fiber with embedded YAG: Ce3+ so the fiber emits white light emission under blue excitation.
This study employed an optimized optomechanical test bench setup to first characterize light source, single-mode and multi-mode configurations, along with broadband white light sources to determine the most efficient excitation source for the above-mentioned fibers. This study identified wavelength-stabilized single-mode laser diode as optimal for stable upconversion excitation. The spectral emission, transmission profiles, and length-dependent attenuation were recorded for all fiber types.
We demonstrate that the tellurite fiber exhibits long-lasting green afterglow following 980 nm excitation. The bioactive composite fiber maintains red emission and structural integrity after pro-longed immersion in simulated body fluid, confirming their potential for biomedical applications. The YAG: Ce3+ containing fiber produces broad, spectrally stable emission with reduced scattering losses at shorter lengths.
This work provides a comprehensive characterization of composite optical fibers linking excitation conditions, and fiber geometry to their resulting transmission, loss, and emission behavior. The findings establish clear performance of composite fibers with green persistent luminescence, red upconversion, and white light emissions, offering valuable guidelines for the future development of multifunctional luminescent fibers in photonic, biomedical, and lighting applications.
Three distinct fiber types were investigated starting with Tm3+, Yb3+ codoped tellurite glass fibers prepared with the green persistent luminescent SrAl2O4:Eu2+, Dy3+ particles so that the fiber emits long lasting green light after near-infrared (NIR) charging. The second fiber was a bioactive glass-based fiber prepared with red upconversion crystals, Y2Ti2O7: Er3+ (28 mol%) for potential local drug release applications by converting the NIR light into red light. The third fiber was a phosphate glass-based fiber with embedded YAG: Ce3+ so the fiber emits white light emission under blue excitation.
This study employed an optimized optomechanical test bench setup to first characterize light source, single-mode and multi-mode configurations, along with broadband white light sources to determine the most efficient excitation source for the above-mentioned fibers. This study identified wavelength-stabilized single-mode laser diode as optimal for stable upconversion excitation. The spectral emission, transmission profiles, and length-dependent attenuation were recorded for all fiber types.
We demonstrate that the tellurite fiber exhibits long-lasting green afterglow following 980 nm excitation. The bioactive composite fiber maintains red emission and structural integrity after pro-longed immersion in simulated body fluid, confirming their potential for biomedical applications. The YAG: Ce3+ containing fiber produces broad, spectrally stable emission with reduced scattering losses at shorter lengths.
This work provides a comprehensive characterization of composite optical fibers linking excitation conditions, and fiber geometry to their resulting transmission, loss, and emission behavior. The findings establish clear performance of composite fibers with green persistent luminescence, red upconversion, and white light emissions, offering valuable guidelines for the future development of multifunctional luminescent fibers in photonic, biomedical, and lighting applications.