Optical bonding with fast sol-gel

Abstract

We investigate here the properties of fast sol-gel for optical bonding. The precursors of the fast sol-gel material are organically modified alkoxides generating a transparent hybrid (organic-inorganic) substance with silica glass-like properties whose index of refraction can be modified by the addition of various metal-oxides. The fast sol-gel method consists of rapid fabrication of a viscous resin and its subsequent dilution for long shelf life use. This material, when used as an adhesive offers the option of either a thermal or UV curing procedure. We demonstrate a bonding strength of ∼ 10 MPa when a 15 µm layer is applied between two glass elements. The bonding remained stable after an extensive −40°C – 120°C temperature cycling with minimal residual solvent evaporation at 150°C. The fast sol-gel material was tested for optical bonding between silica bulks, between silica bulk and silicon wafers and as an adhesive in silica fibre couplers.

Keywords

• optical bonding
• sol-gel
• ormosils
• refractive index
• thermal stability