Optically Tunable Transient Plasmons in InSb Nanowires.

Optical carrier incubation can effectively alter the electron transport properties of semiconductors; thus, optical switching of the plasmonic response of the semiconductor enables the ultrafast manipulation of the light at the nanoscale. Semiconductor nanostructures are promising platforms in on-chip high-speed plasmonic devices, owing to their high photoinduced electron injection efficiency at sub-picosecond and compatibility with contemporary semiconductor technologies. The pure single-crystalline InSb nanowires are promising plasmonic materials in the mid-infrared region due to their high electron mobility and small electron effective mass. Here, we utilize the pump-probe nanoscopy to investigate the pump fluence dependency and the dynamics of the non-equilibrium plasmons in the InSb nanowires. We successfully switch the InSb plasmon by injecting the photo-induced electrons and show the practical tuning of the plasmon frequency to one octave by increasing the pump fluence from 0 to 90 μJ/cm 2 . The density of the photo-induced electrons in InSb nanowires is 18.8×10 18 cm -3 with pump fluence as low as 90 μJ/cm 2 . The high electron mobility of the InSb supports the low-loss plasmon with a damping rate of about 200 cm -1 . The InSb nanowires' excellent plasmonic properties ensure they are a promising platform for upcoming high-speed mid-infrared plasmonic materials for informatic devices. This article is protected by copyright. All rights reserved.