Nd:LaF/sub 3/ channel waveguide lasers fabricated by molecular beam epitaxy

Summary form only given. Recently we demonstrated the first laser action in a neodymium-doped lanthanum fluoride planar waveguide. This was the first laser action achieved in a RE-doped fluoride thin-film fabricated by MBE. The fabrication technique allows very accurate control of the thickness and doping level of the thin film, and potentially also over the refractive index profiles. Here we report on investigations into producing slab-loaded channel waveguide lasers based on these MBE planar thin films, to further lower the laser threshold and give a more circular spatial output. The first fabrication technique reported, employs an organic photodefinable polymer (benzocyclobutene) that can be processed using standard photolithographic techniques to produce the type of structures where various width polymer strips are laid over the Nd:LaF/sub 3/ thin film. Although benzocyclobutene´s potential for producing integrated optical devices is well recognised we believe that this is the first demonstration of active laser channels that incorporate this polymer. We report laser operation at both 1.06 and 1.3 /spl mu/m, with thresholds as low as 15 mW (incident power) for these structures. We also report the fabrication and laser operation of channels produced by etching via ion beam milling through a CaF/sub 2/ upper cladding. The prospects for the future development of mid-IR laser sources based on this technology are discussed.