  In this work a hybrid nanoplasmonic-Weyl Semimetal (WSM) structure is
realized for the first time utilizing silver nanopatch antennas and WSM
Tantalum Arsenide (TaAs). The studied hybrid WSM-nanoplasmonic structure
demonstrated a substantial, over x4.5 enhancement of the second harmonic
generation (SHG) process compared to a bare TaAs film. To realize the hybrid
structure while preserving TaAs properties, a scalable, non-destructive
manufacturing approach was developed that involves the fabrication of TaAs
flakes from single crystalline TaAs, overgrowth of a silicon nitride overlayer,
and drop-casting of silver nanopatch antennas. The strong polarization response
of both the bare flakes, along with the hybrid-nanoplasmonic cavities
demonstrates that this approach uniquely preserves the TaAs crystal structure
and its optical response while providing significant enhancement of the
nonlinear properties. The developed method allows leveraging the capabilities
of plasmonics to control and enhance light-matter interactions at the nanometer
scale to access and engineer WSM response. This work is the first step towards
high-performance nanophotonic devices utilizing WSM topological properties.
