A method of forming an optical fibre assembly, comprises providing a planar substrate made of a first material; positioning an optical fibre with an outer layer of a first glass material on a surface of the substrate to form a pre-assembly; depositing a further glass material such as silica soot onto the pre-assembly, over at least a part of the optical fibre and adjacent parts of the substrate surface; and heating the pre-assembly to consolidate the further glass material into an amorphous volume in contact with at least parts of the surface of the substrate and the outer layer of the optical fibre, thereby bonding the optical fibre to the substrate to create the optical fibre assembly.