Simple and reusable fibre-to-chip interconnect with adjustable coupling eficiency

A simple, efficient and reusable fiber-to-chip interconnect is presented. The interconnect is based on a V-groove (wet- chemically etched) in silicon, combined with a loose-mode Si3N4-channel waveguide. The loose-mode waveguide is adiabatically tapered to the integrated optical (sensor) circuitry. This adiabatic taper enables the dimensions of both the integrated optical sensor circuitry and the loose- mode waveguide section to be designed independently. The coupling efficiency of the `plug-it-in' interconnect is tunable between zero and the maximum obtainable value by tightening two adjustment screws. Coupling efficiencies up to 60% using TE-polarized light at wavelength of 632.8 nm have been reproducibly measured.