| Several different glass materials were investigated for waveguide amplifier and laser applications, and the potential to realize practical devices with these materials were examined using waveguides fabricated by ion exchange processes.; Channel waveguides in an erbium doped phosphate laser glass were fabricated by a dry silver-film ion exchange technique, and the effects of high Er{dollar}sp{lcub}3+{rcub}{dollar} concentration were investigated in terms of Er{dollar}sp{lcub}3+{rcub}{dollar} ion interactions and energy transfer from Yb{dollar}sp{lcub}3+{rcub}{dollar} to Er{dollar}sp{lcub}3+{rcub}{dollar}. Cooperative upconversion coefficients of the {dollar}rmsp4Isb{lcub}13/2{rcub}{dollar} level,{dollar}7.7pm0.7times 10sp{lcub}-19{rcub} cmsp3{dollar}/sec and {dollar}9.3pm0.7times10sp{lcub}-19{rcub} cmsp3{dollar}/sec, were obtained experimentally for Er{dollar}sp{lcub}3+{rcub}{dollar} concentration of {dollar}1times10sp{lcub}20{rcub}{dollar} cm{dollar}sp{lcub}-3{rcub}{dollar} in the bulk and waveguide samples, respectively. These values are one order of magnitude smaller than the ones reported for silica glass. The increase in the cooperative upconversion coefficient with the increase in Er{dollar}sp{lcub}3+{rcub}{dollar} concentration was found to be small. The effects of cooperative upconversion on the gain performance were analyzed for different Er{dollar}sp{lcub}3+{rcub}{dollar} concentrations using a theoretical model which adopted experimentally obtained parameters. Given the small cooperative upconversion coefficients in this glass, Er{dollar}sp{lcub}3+{rcub}{dollar} concentrations potentially as high as {dollar}3.7times10sp{lcub}20{rcub}{dollar} cm{dollar}sp{lcub}-3{rcub}{dollar} were shown to be feasible by the modeling. This would result in a 12 dB gain with a 4 cm long waveguide for 150 mW pump power at 1.48 {dollar}mu{dollar}m. The transfer efficiency from Yb{dollar}sp{lcub}3+{rcub}{dollar} to Er{dollar}sp{lcub}3+{rcub}{dollar} was found to be 95% or higher for samples with Er{dollar}sp{lcub}3+{rcub}{dollar} concentrations of {dollar}1.9times10sp{lcub}20{rcub}{dollar} cm{dollar}sp{lcub}-3{rcub}{dollar}, and {dollar}24times10sp{lcub}20{rcub}{dollar} cm{dollar}sp{lcub}-3{rcub}{dollar}, even when the ratio of the concentrations, Yb/Er, is only about 1.2 and 2.; Planar channel waveguides of rare-earth doped fluoride glass were demonstrated with single mode excitation and propagation loss below 3 dB/cm. The waveguide core was fabricated by {dollar}rm Agsp+{dollar}-Na{dollar}sp+{dollar} molten salt ion exchange process in a borosilicate glass (BGG31), and a Nd{dollar}sp{lcub}3+{rcub}{dollar}-doped ZBLAN glass was used as a cladding. A 0.45 dB signal amplification at 1.064 {dollar}mu{dollar}m was observed in the fabricated 1cm long waveguide, and a 0.9 dB amplification is expected at the emission peak (1.049 {dollar}mu{dollar}m). Modeling results suggest that 2.5 dB/cm is possible by improving surface flatness of the ZBLAN glass. |
