Out-of-Plane Coupling Structures for Packaging and Benchmarking

Efficient optical coupling between integrated photonic circuits and external optical components remains a key challenge in photonic packaging and wafer-level characterization. Out-of-plane coupling structures, such as grating couplers and mirror-based interfaces, play a crucial role in enabling automated testing, fiber attachment, and optical interconnect integration. The performance of these structures directly impacts insertion loss, alignment tolerances, polarization dependence, and overall packaging cost.

This internship focuses on the design, simulation, and optimization of out-of-plane coupling CMOS-based structures that are co-integrated with polymer waveguides. The work will investigate both grating-coupler-based and mirror-based solutions, considering their suitability for packaging and wafer-level benchmarking. Different grating architectures, including 1D and 2D designs, will be evaluated with respect to coupling efficiency, polarization sensitivity, and fabrication compatibility. Special attention will be given to the transition region between the grating and the single-mode waveguide, where advanced non-linear taper designs can be used to improve mode matching and reduce optical losses.