WAVE-GUIDES IN YLF GROWN BY LIQUID-PHASE EPITAXY

Crystalline waveguides were grown by liquid-phase epitaxy (LPE) of LiY (1-x-y)Ln(x)Gd(y)F(4) (Ln = Nd, Er; y = 0.1) layers on LiYF4(YLF) subs trates. The Gd co-doping increases the difference In the refractive in dexes of the layer and the substrate. Besides planar waveguides, ridge -type waveguides could also be obtained by mechanical polishing. By gr owing a cladding layer of YLF on top of the waveguides, buried planar and ridge waveguides were fabricated. Laser operation was achieved for a buried LiY0.89Nd0.01Gd0.1F4 ridge waveguide end-pumped with a laser diode operating at 806.5 nm. For the buried LiY0.89EC0.01Gd0.1F4 laye rs, intense upconversion luminescence was observed in low optical loss waveguides.