  Double Nanohole Plasmonic Tweezers (DNH) have revolutionized particle
trapping capabilities, enabling trapping of nanoscale particles well beyond the
diffraction limit. This advancement allows for the low-power trapping of
extremely small particles, such as 20 nm nanoparticles and individual proteins.
However, to mitigate the potentially amplified effects of plasmonic heating at
resonance illumination, DNH plasmonic tweezers are typically operated under
off-resonance conditions.Consequently, this results in a decrease in optical
forces and electric field enhancement within the plasmonic hotspot, which is
undesirable for applications that require enhanced light-matter interaction
like Surface Enhanced Raman Spectroscopy (SERS). In this study, we present a
novel design for DNH plasmonic tweezers that addresses these limitations and
provides significantly higher field enhancements. By introducing a reflector
layer, on-resonance illumination can be achieved while significantly reducing
plasmonic heating.This reflector layer facilitates efficient dissipation of
heat both in-plane and axially. Furthermore, the integration of a reflector
layer enables a redistribution of hotspots via Maxwell's boundary conditions
for metals, creating more accessible hotspots optimal for applications that
require enhanced light-matter interaction. We also demonstrate low-power
trapping of small extracellular vesicles using our novel design, thereby
opening possibilities for applications such as SERS and single photon emission
that require intense light-matter interaction.
