1 research outputs found
Plasmonic Hot-Electron Injection Driving Ultrafast Phase Transition in Self-Supported VO<sub>2</sub> Films for All-Optical Modulation
VO2 has been widely used
in optical modulation
devices
due to its large change in permittivity across its first-order metal–semiconductor
phase transition. People have proved that VO2’s
phase transition can be driven by plasmonic hot-electron injection,
providing a new approach to realizing ultrafast all-optical devices
with a low pump fluence. Here, we report on ultrafast VO2 all-optical modulation with a dramatically low pump fluence utilizing
the composite structure of a self-supported VO2 film on
a gold nanoshell grating. Plasmonic hot electrons in the gold excited
by femtosecond pulses are injected into the VO2 film and
trigger its phase transition, reducing the pump fluence threshold
for the structural transformation to only 147.8 ÎĽJ/cm2. With a pump fluence above this threshold, ultrafast phase transition
can be triggered within 1 ps, and a high modulation depth of 50% can
be achieved. Moreover, an ultrafast modulation with an on–off
time of 650 fs can also be achieved using a pump fluence below the
threshold. This work may explore new applications of plasmonic hot-electron-driven
phase transition in optical modulation devices and configurable devices