Semiconductor laser array to fibre array coupling via diffractive microlenses

The authors have shown that there are considerable difficulties in forming satisfactory arrays of conventionally lensed fibres and that the traditional means of coupling single fibres to single devices are not practical for arrays. They have also shown how an array of Fresnel lenses has been produced in quartz and also how such an array may be formed to include an integral fibre alignment structure. At present the lenses produced show coupling efficiencies between 30° FWHP semiconductor lasers and cleaved singlemode fibres of 34%. This is less than the 60% that can be achieved with a good lensed fibre but such an array could be used when high coupling is not required. Further development is required to increase the coupling efficiency. It has also been shown how a lensed array may be utilised in a package using laser welding as the fixing technology