Abstract

There has recently been much work on fabricating waveguide lasers based on crystal hosts by methods such as crystal fibre growth¹, ion-exchange², in-diffusion³, ion-implantation⁴, and epitaxial growth⁵. Despite the confinement of pump and signal beams to a few microns spot size, in general these lasers have not shown a clear advantage over bulk lasers in terms of thresholds due to propagation losses of the order of 0.1dB/cm or higher. Here we identify laser systems in which crystal waveguides will show great advantages over bulk lasers, namely 3 level and quasi-3 level transitions, and as an example describe the low threshold operation of a 946nm Nd:YAG epitaxial waveguide laser. The extra cavity loss arising from using a waveguide is less significant in (quasi-) three level systems as re-absorption loss from the lower laser level is present.

© 1993 Optical Society of America