High performance hermetic package for LiNbO3 electro-optic waveguide devices

The authors report a modular approach to the packaging of LiNbO ₃ waveguide devices. The LiNbO₃ chip is soldered into a fully hermetic submodule and laser welding is used to secure optical fibres which are glass sealed into fibre subassemblies. The technique has also been extended to directional coupler devices by the use of a novel double fibre subassembly. In order to reduce optical reflections, chip facets and fibre ends are antireflection coated using low temperature ion assisted deposition techniques to avoid possible damage to LiNbO₃ chips and fibre jackets. The submodule is mounted in an external package which provides additional protection and can be used to house additional optical and electronic components. They report detailed characterisation of a prototype high speed travelling wave LiNbO₃ Mach-Zehnder modulator packaged according to this concept