Semiconductor nanowire lasers have attracted intense interest as promising compact, low-power coherent light sources for on-chip applications, many of which (e.g., imaging, multiplex communication, data storage) desire high beam quality and spectral purity—conditions that can be satisfied by single-mode operation in nanowire lasers. However, due to the lack of mode-selection mechanisms, most reported nanowire lasers exhibit multimode behavior.
To date, single-mode lasing with high side-mode suppression ratios in nanowires has required complex micromanipulation of the ends of individual nanowires, but nanophotonic applications require easily fabricated nanowire lasers that exhibit single-mode lasing. George Wang’s work reports on single-mode lasing in as-fabricated, straight, monolithic gallium-nitride (GaN) nanowires with linewidths of ~0.12 nm and >18 dB side-mode suppression ratio.
In general, GaN-based nanowire lasers could enable applications such as nanoscale optical probes, nanolithography, and nanoscale optical chip elements. Arrays of GaN-based nanowire lasers could help provide high efficiency lighting for displays and solid-state lighting. Understanding and controlling the optical emission through careful design and fabrication as demonstrated in George’s work is an important step toward all nanowire-laser-based applications.