Ultrafast pulsed lasers with pulse durations of 40-100 fs are used to deposit rare earth doped tellurite glass onto silica glass substrates in a pulsed laser deposition (PLD) chamber. Under certain conditions, the tellurite glass plasma mixes with the silica glass network producing a thin glass film of tellurite-modified-silica which produces some unique physical, and when doped with rare earth ions, spectroscopic properties. Layers of tellurite-modified-silica glass up to 2 µm thick have been produced with refractive indices of around 1.65, compared to 1.46 and 2.0 for the silica substrate and tellurite target glasses, respectively. Electron microscopy of the thin films shows a sharp and well defined boundary between the modified layer and the pristine substrate, and X-ray spectroscopy (EDX) confirms that the constituent ions of the target glass are uniformly distributed within the substrate silica glass network. Rare earth ions can be doped into these layers in concentrations which are higher than would be possible in pure silica glass without clustering, and Er3+ for example exhibits unusually long 1535 nm fluorescence lifetimes in these thin films. Tm3+ ions have also been doped into these layers, yielding longer wavelength fluorescence, up to around 2000 nm. By codoping Tm3+ and Er3+ ions, broadened fluorescence bands are possible which are of interest for broadband optical amplification. Additionally, codoping with Yb3+ allows efficient excitation using a convenient ~980 nm laser diode source. This technique of producing thin films is also being used to integrate dissimilar materials such as semiconductors, polymers and glass. In this presentation, we will describe the fabrication of rare earth doped tellurite-modified-silica thin films; the physical characterisation of the films including thickness, refractive index and surface roughness; and the optical properties such as transmission and fluorescence.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)