EPITAXIAL ND-YLF LINEAR WAVE-GUIDE LASER

We report laser operation in planar and linear Nd:YLF waveguide struct ures grown by liquid-phase epitaxy (LPE). We could reduce the relative ly high threshold of 115-mW incident pump power observed for the plana r waveguide to 8 mW in a ridge-type structure that we obtained by mech anical polishing and subsequent growth of a cladding layer. Substantia l improvements seem possible with reduction of the losses caused by im perfect end-face reflection and scattering, as well as by use of techn iques capable of producing smaller structures than the 40-mu m-wide tr iangular ridge cross section that was obtained with polishing. Since t he LPE technique is applicable to other activator ions as well, it mig ht offer a route to development of low-threshold upconversion lasers. (C) 1997 Optical Society of America.