Far-Field Directionality Control of Coupled InP Nanowire Lasers.

Abstract

Nanowire (NW) lasers are promising compact, coherent on-chip light sources for next-generation optical communication and imaging. However, controlling their emission directionality has been hindered by the complexities of lasing mode engineering and fabrication. Here, we demonstrate spatially engineered far-field emission from vertically emitting InP NW lasers by precisely controlling optical coupling between site-selective NWs, without postepitaxy transfer or alignment. Leveraging this process capability, we design and grow NW pairs and triplets that lase in the TE01 waveguide mode. By tuning the optical coupling gap, we transform their far-field profiles from doughnut-like to double-lobed, in close agreement with simulations. Numerical studies further show that arranging NW pairs in a periodic array enhances far-field directionality, demonstrating the potential for a directional lasing metasurface. Our results provide a foundation for efficient integration of coherent light generation and beam steering in on-chip light sources.