to make a low loss connection between the core of a single mode optical fibre and a waveguide on a waveguide substrate , a support block which straddles the waveguide is mounted on the waveguide substrate . the end - face of the optical fibre is fixed to both the waveguide substrate and the support block with transparent , light curable , adhesive . the support block may be affixed to the substrate with the same adhesive as is used to fix the optical fibre to the substrate .