Deep Sub-Wavelength 3D Imaging Using a Single Nanowire Detector

Nanowires have an ideal shape for high-resolution imaging, with a small cross-section for high resolution and a long length for strong absorption. However, since the absorption in nanowires is dominated by nanophotonic effects, it is unclear what resolution and efficiency such devices could offer. Here, we investigate the limits of spatial resolution and efficiency of nanowire-based direct detectors using experiments and optical modeling. We demonstrate a direct detection scheme using a single pixel detector based on an InP 80 nm diameter nanowire diode by 3D imaging with a laser focus. Our detector has an apparent peak responsivity of 2.9 AW^-1 and a dynamic range of approximately 10⁶ in intensity. Optical modeling shows a clear optimum for the spatial resolution at around 100 nm nanowire diameter, while even smaller diameters lead to a loss of resolution. Additionally, we find that the nanowire diameter can be optimized for resolution and absorption simultaneously.