Effect of nanofiber/thin-film multilayers on the optical properties of thulium-doped silica-alumina

Hybrid layer of Tm3+-doped SiO2-Al2O3 nanofiber/thin-film demonstrates broad spectral width with notable high emission intensity. This multilayer structure comprised of thin film sandwiched between two nanofiber-layers, and was prepared via sol gel dip coating and electrospinning techniques, respectively. The emission spectrum achieved more than 5-fold enhancement at 680-nm wavelength and about 51-nm spectral-width, as compared to the emission from a thin film layer. The emitted spectrum peaked at shorter wavelength by about 30 nm from the spectral peak intensity of thin film. The manifestation of the nanostructured layers, which alters the energy levels of Tm3+ due to confinement of the ions in low dimensional structure combined with the effect from thin film, resulted in the spectral broadening and increased of spectral intensity. The order of depositing the nanofiber/thin film layers affects the luminescence intensity and peak spectrum wavelength. Thus, tailoring the order in which these layers are to be deposited allows a particular emission characteristic to be achieved.