Laser direct writing of SiO 2 /TiO 2 sol-gel films to fabricate stripe optical waveguides

Abstract

SiO₂-TiO₂ planar optical waveguides are fabricated on silicon wafer substrate by dip-coating technique with the Sol-Gel solutions, based on which the stripe optical waveguides are patterned by laser direct writing of the Sol-Gel films using an Ytterbium fiber laser and followed by chemical etching. The effects of the laser processing parameters on the microstructure of the core layer films are investigated. The relative chemical etching rates of the non-irradiated area in Sol-Gel films that are haeted at different temperature are characterized. The optical fields and propagation losses of the optical waveguides at the wavelength of 1550 nm are characterized by multi-channel fiber/waveguides coupling system. The experimental results demonstrate that the composition, the post heat treatment temperature and laser power density have a big effect on the widths of the stripe optical waveguides, and the minimum widths about 25 μm can be fabricated with the suitable parameters. The core layer of the planar optical waveguides as received by Sol-Gel method is loose in structure, and a shrinkage concave groove forms in the laser irradiated area. The microstructure and forming mechanisms of the stripe waveguides by laser direct writing Sol-Gel films are discussed. The minimum propagation loss of the fabricated stripe waveguides is about 1.77dB/cm at 1550nm. Better results are expected by improving the film composition and laser processing parameters further.