Photonic crystal nanolasers wedged in silicon-based waveguides

This work presents, to our knowledge, a novel hybrid integration in an end-coupling configuration by directly wedging III-V photonic crystal nanobeam (NB) lasers into silicon-based waveguides. The nanocavity, featuring a reduced lattice period on one side, achieves a theoretical unidirectional coupling efficiency exceeding 92% into the silicon waveguide without requiring additional mode converters. By employing a highly accurate transfer printing technique assisted by two-dimensional mechanical guidance, this wedging configuration exhibits highly unidirectional coupling from the NB lasers into the silicon-based waveguides, along with low wavelength dependence and significant tolerance to transfer printing misalignments. Furthermore, wedging the NB lasers into single and double U-bend waveguides with long propagation lengths produces significant planar emission, thereby initially confirming the feasibility of this configuration as a nano-light source for photonic circuits.