Optically assisted chemical surface microstructuring of LiNbO/sub 3/

Summary form only given. Preferential wet etching of LiNbO/sub 3/ surface is reported, based on two distinct methods of optical treatment of the material´s surface. (a) Excimer laser-induced surface damage followed by wet etching with a mixture of HF-HNO/sub 3/ acids, where an excimer laser is used for printing an interference pattern on the surface of LiNbO/sub 3/ in the form of periodic damage on the high intensity areas of the interference fringes. Wet etching, following the exposure of the material´s surface, preferentially attacks the affected areas leading to higher etch rates, thus revealing the grating and also removing the debris produced by the ablation procedure. The method can be applied to any crystallographic orientation. (b) The second method is applied to the z face of iron doped LiNbO/sub 3/ niobate which has been thermally fixed to produce an ionic charge distribution created by two-beam interference. Again, preferential etching occurs revealing the space charge field pattern. Clearly the etching procedure is affected by the fixed ionic space charge distribution since the grating has been revealed in both developed and undeveloped crystals. The methods have been applied to fabricate grating structures onto titanium in-diffused LiNbO/sub 3/ channel waveguides and preliminary spectral filtering results are presented.