Integration of Photonic Crystal Nanolasers with V-Shaped Nanoslots into Silicon Waveguides

This study demonstrates an end-coupling configuration that integrates a III–V slotted nanobeam (NB) laser into an air-clad silicon-on-insulator waveguide. This integration is realized by simultaneously assembling and wedging two identical NBs into a waveguide notch in a single step via a mechanically guided transfer-printing technique. The assembled NB features a novel nanoslot with a V-shaped cross-section and a minimum width of approximately 6 nm, enabling extreme field concentration at the slot opening─a characteristic highly beneficial for enhancing light–matter interaction with the surrounding media. By incorporating reduced lattice periods on the NBs and a multimode interference (MMI) coupler design on the silicon waveguide, a theoretical unidirectional coupling efficiency exceeding 80% is achieved for the V-slotted mode. Statistical analysis across multiple devices confirms uniformly high laser emission coupling into the silicon waveguides within the MMI coupling bandwidth. Furthermore, we investigate the impact of various transfer-printing misalignments on the coupling, confirming its robustness and uniformity within the achievable tolerances of our process. These findings provide a reliable approach to implementing slotted active devices in silicon-based photonic circuits, offering significant advantages for diverse applications requiring enhanced light–matter interactions.