Enhanced terahertz emission from mushroom-shaped InAs nanowire network induced by linear and nonlinear optical effects

Abstract

The development of powerful terahertz (THz) emitters is the cornerstone for future THz applications, such as communication, medical biology, non-destructive inspection, and scientific research. Here, we report the THz emission properties and mechanisms of mushroom-shaped InAs nanowire (NW) network using linearly polarized laser excitation. By investigating the dependence of THz signal to the incidence pump light properties (e.g. incident angle, direction, fluence, and polarization angle), we conclude that the THz wave emission from the InAs NW network is induced by the combination of linear and nonlinear optical effects. The former is a transient photocurrent accelerated by the photo-Dember field, while the latter is related to the resonant optical rectification effect. Moreover, the p-polarized THz wave emission component is governed by the linear optical effect with a proportion of ∼85% and the nonlinear optical effect of ∼15%. In comparison, the s-polarized THz wave emission component is mainly decided by the nonlinear optical effect. The THz emission is speculated to be enhanced by the localized surface plasmon resonance absorption of the In droplets on top of the NWs. This work verifies the nonlinear optical mechanism in the THz generation of semiconductor NWs and provides an enlightening reference for the structural design of powerful and flexible THz surface and interface emitters in transmission geometry.

Interplay between Ultrafast Shift Current and Ultrafast Photon Drag Current in Tellurium Nanotubes

“…For instance, the built-in surface depletion field depends on the doping type and the photo-Dember effect is determined by the difference of the carrier mobility . At this point, the THz radiation presents consistent waveforms under the p - and s -polarized excitations in the bulk WS 2 and mushroom-shaped InAs nanowire, which are dominated by the surface field effect and photo-Dember effect, respectively. Therefore, we can reasonably infer that the primary THz emission mechanism from the Te nanotubes is related with the nonlinear optical effect.…”

Semiconductor THz Emitting Nanometasurface (STEN)

“…Furthermore, the nonlinear effect has been explored as a facet of surface emission. [ 24 − 26 ] While previous reports have shown promising results with nanoscale dielectric metasurfaces in enhancing THz surface emission, there is a lack of studies that specifically address the low‐power pump scenario. Such investigations are crucial for advancing the application of surface emission techniques.…”