Helmut Sautter

Fluorescent Er2O3 doped lead silicate glass for optical amplifiers

A hot-pressing method is investigated for the fabrication of a planar optical waveguide amplifier. Therefore commercially available LaSFN15 produced by Schott is used as substrate and cladding material in combination with Er2O3 doped lead silicate glass as core material, synthesised by a hybrid sol-gel melting technique. The lead silicate glass is selected for its low melting temperature required for the waveguide processing. The core glass is adapted to the LaSFN15 with respect to the thermal expansion coefficient and the refractive index. The composition suited for the hot-pressing technology is evaluated to be 45 mole% PbO and 55 mole% SiO2. The influence of increasing Er2O3 content to these parameters is compensated by changing the molar ratio of PbO/SiO2. The optimal composition of the doped core glass is found out to be a glass containing around 3 wt.% Er2O3 because concentration quenching accurs above.

Short amplifying planar waveguides by new glass processing technology

Short amplifying waveguides in which the dopand is confined to the waveguide core were realized by a new glass processing technology with high demands to the optical and thermal properties of the core, cladding and substrate glass. By the improvement of the etching procedures primary structures with a roughness of less than 50 nm were obtained. Simulations, which showed that in a 12 cm waveguide 20 dB gain can be achieved at 1549 nm, were made to evaluate the potential of the amplifier. Gain measurements were performed in waveguides with a dopand concentration of 3 wt.% erbium and an internal gain of more 3.7 dB was achieved in a 1.8 mm glass waveguide at a wavelength of 1549 nm.