Semiconductor nanowires are critical for advancing the miniaturization of optoelectronic devices due to their waveguiding properties, high optical gain, and low power consumption. They are particularly promising for realizing compact nanolasers. Optical coupling between adjacent nanowires leads to interesting phenomena, including mode-splitting and directional far-field emission, which are useful for nanoscale photonic applications. We present a detailed study on ZnO and InP nanowires, focusing on their growth, optical coupling, and far-field emission properties.

ZnO nanowires, grown via chemical vapor deposition (CVD), were studied in a planar geometry on a SiO₂ substrate. Efforts were made to improve their growth process and achieve vertical alignment for future applications. Optically pumping these nanowires provided insights into the spectral emission at each end, revealing sub-cavity effects due to the nanowire geometry and arrangement, allowing us to deduce coupling strength.

In contrast, InP nanowires were vertically grown using metal-organic chemical vapor deposition (MOCVD) and arranged into defined pairs and triplets with controlled gaps (50–150 nm). Far-field emission patterns from these nanowires were measured using micro-photoluminescence and back-focal-plane imaging. Our results align well with simulations and demonstrated that optical coupling between nanowire cavities split the lasing TE01 mode into TE01-a and TE01-b. These modes exhibited nearly identical electric field distributions within the nanowires but drastically different and orthogonal far-field emission patterns. This directional emission introduces a novel mechanism for shaping far-field emission in arrays of nanolasers.

Building on this, we fabricated arrays of InP nanowire pairs. Simulations showed that coherent interference between coupled nanowire pairs results in narrower and more directed far-field emission, an observation to be corroborated by experiments. This opens avenues for designing nanolaser arrays with tailored emission profiles.