Butt-Coupling Optical Probe Card for Wafer-Scale Photonic-Integrated-Circuits Test with Polarization Control
Wafer-scale Si photonics testing through grating couplers has a great progress nowadays. Together with an image processing technique, a fully automated wafer-scale testing platform has been demonstrated. However, most of the devices are eventually diced and packaged with fiber arrays through edge coupling. Therefore, high-speed, on-wafer testing of device through edge coupling is preferable. Nevertheless, on-wafer coupling light to the waveguide edges without chip dicing is critical. Several approaches to fabricate optical probes for on-wafer edge coupling have been proposed, such as obliquely cutting the PLC chip or using a 3D printing technique to make a lens-shaped structure at the end of a fiber tip. All these approaches are to direct the guided wave from the top surface to the free space horizontally and illuminate light to the waveguide facet. However, fabricating these optical probes requires precision machining and assembly.