PLANAR OPTICAL WAVE-GUIDES FABRICATED BY MOLECULAR-BEAM EPITAXY OF PB-DOPED CAF2 LAYERS

Molecular beam epitaxy of rare-earth-doped CaF2 layers has already bee n demonstrated. Optical waveguiding can be obtained if the refractive index variation due to the rare-earth doping is high enough. To tailor separately the refractive index profile and the active ion profile in the layer, the former should be modified by a passive impurity. This letter demonstrates that passive waveguides can be obtained in CaF2 ep itaxial layers by the introduction of moderate concentrations of Pb. M onomode planar waveguides with a steplike index variation ranging from 0.2% to 1.2% (relative to CaF2) have been grown and characterized, pa ving the way for the independent engineering of refractive index and a ctive center distributions in optical active waveguide devices made of this kind of material. (C) 1997 American Institute of Physics.