Laser micromachined 3D glass photonics platform demonstrated by temperature compensated strain sensor

A platform for integrated glass solutions with full 3D capabilities based on femtosecond laser micromachining is presented. The design and fabrication of different building blocks, such as optical waveguides, bragg gratings, V-grooves and (freestanding) microstructures are described. The capabilities of the platform are exemplified by designing a temperature compensated strain sensor composed of two Bragg grating sensors, where one Bragg grating sensor is mechanically isolated by means of a cantilever, while the other is embedded in the bulk of the glass. Both Bragg gratings exhibit a similar temperature sensitivity of about 10.5 pm/°C. It is proven that the isolated Bragg grating does not experience strain, while the other one does with a sensitivity of 1.1 pm/με; thus allowing temperature compensation. Integrated V-grooves allow for a fully fiber-packaged strain sensing solution, directly applicable in many structural health monitoring applications. The versatility of the platform is further illustrated by the widely varying building blocks.