Passive ridge waveguides can be deposited on silicon by a solvent-assisted lithographic process incorporating simple mask technology and photosensitive solgel-derived glasses. Thick films (~4 mum) are dip coated in one step, and channel waveguides and power splitters are imprinted in them by UV light through appropriate masks. Unexposed regions of the glass are removed by soaking of the films in n-propanol. The remaining ridges are then treated at 200 degrees C and planarized with a solgel cladding layer. Circular mode profiles are observed from ridge guides covered with the cladding. The waveguides are characterized with scanning electron microscopy, atomic force microscopy, surface profilometry, ellipsometry, and fiber end coupling. Overall, the procedure is simple and reproducible and leads to waveguides with low loss, of the order of 0.13 dB/cm.

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ChemInform Abstract The title compounds with 0 < x ≤ 0.3, prepared by heating mixtures of MVO3 and LaVO3 to 1420-1470 K for 60 h, have the perovskite structure. The lithium compounds La1-xLixVO3 have a structure which is analogous to that of LaVO3 (GdFeO3 type, space group Pbnm), whereas the remaining compounds La1-xMxVO3 (M: Rb, Cs) have a rhombohedrally distorted perovskite structure (space group D6 3d-R3c). LaVO3 is known to be a p-type semiconductor. The title compounds, however, change the character of their conductivity from p-type at low temp. to metallic at elevated temperatures.