Erbium-doped glasses for waveguide laser applications

Erbium doped glasses have much potential for active devices operating in the 1.5 mum spectral region. In particular, waveguide devices may be useful as integrated sources or amplifiers for wavelength division multiplexing telecommunications systems, or as laser sources for applications requiring an eye safe wavelength. The demonstration of short waveguide devices require substantial gain per unit length. The achievable gain in erbium doped glasses is limited by the onset of concentration quenching at relatively low dopant levels. Concentration quenching is commonly attributed to the formation of clusters of rare earth ions. Interactions between ions in these clusters are believed to lead to rapid nonradiative decay of excited ions. This thesis addresses various issues related to the development of active devices in rare-earth doped glass materials.; In order to investigate the question of whether clusters of rare earth ions exist, a structural probe, Extended X-ray Absorption Fine Structure (EXAFS) is used to examine the environment of the active erbium ions. The erbium environment is investigated both as a function of host glass and also as a function of the concentration of erbium ions.; Results of an extensive optical characterization of the rare-earth doped glasses are also presented. The Judd-Ofelt technique is utilized in order to determine such quantities as the purely radiative excited state lifetime as well the stimulated emission cross section. Measurements of the excited state lifetime show significant concentration quenching. A simulation of excited state decay is presented in which the observed concentration quenching behavior is explained by energy transfer between homogeneously distributed erbium, ions and subsequent quenching by hydroxyl groups.; Waveguides are formed by the ion exchange technique in a multicomponent silicate glass which is codoped with erbium and ytterbium. Ytterbium codoping has been investigated as a way of improving device performance as a result of strong pump absorption by the ytterbium, ions and efficient energy transfer to erbium. The laser performance of these waveguides is then investigated as a function of the ratio of ytterbium to erbium ions. The device length and output coupler reflectivity are also varied simultaneously in order to achieve optimal performance.