Proton exchange anneal proton exchange and reverse proton exchange waveguides in Er:LiNbO3

摘要

Abstract: We report the fabrication, characterization and comparison of waveguides in Z-cut Erbium-doped LiNbO$-3$/, obtained by Proton Exchange, Anneal Proton Exchange and Reverse Proton Exchange (RPE). We found that even in the very low proton concentration ($alpha@-phase) waveguides, the radiative lifetime reduction, hence the fluorescence quenching, of the $+4$/I13/2 $YLD $+4$/I15/2 laser transition due to OH phonons is dramatic. At the contrary, in the RPE waveguides we measured a nearly unaffected lifetime as the ordinary polarized modes are supported by a surface layer nearly free of proton. As it is known that the ordinary polarization is largely advantageous in terms of pump absorption efficiency and relative signal amplification, such waveguides appear to be a workable solution for amplification/lasing around 1.5 $mu@m, provided that the losses due to leakage through the index barrier can be sufficiently reduced.!22