EMBOSSED GRATINGS IN SOL-GEL WAVE-GUIDES - PRE-EMBOSS HEAT-TREATMENT EFFECTS

An embossing technique is used to fabricate surface-relief gratings into SiO2-TiO2 dielectric, step-index, planar optical waveguides, fabricated using a sol-gel process. The influence that a pre-emboss bake cycle has upon the embossibility of the SiO2-TiO2 sol-gel films is described. Through SEM evaluation, the embossed grating ruling profile and general appearance are shown to be strongly dependent upon the duration of the bake at 70-degrees-C. In addition, two embossing surface mechanisms, molding and stress-induced fracturing, are identified and correlated with the duration of the pre-emboss bake. Embossed waveguide gratings with a 0.52-mu-m period and 100-200 nm peak-to-trough depth were fabricated.