Bowtie antennas are actively studied for the very strong field enhancement they provide between the tips of the two triangular nanoparticles, which is known to be inversely proportionnal to the size of the gap. Hence, bowtie nano-antennas are good candidates for surface-enhanced Raman spectroscopy (SERS) applications. Recent advances in lithography techniques allowed the creation of structures with gaps as small as 3 nm, while the typical size of the full structure can get close to 200 nm. Additionally, realistic geometries of such antennas include small roundings at the edges and tips, whose typical size is between a few to a few tens of nanometers.
Here, we show the modulus of the electric field Fourier transform for a pair of 10 nm thick, equilateral prisms of edge length 100 nm, with a spacing gap of 3 nm. The rounding radius is 2 nm, and is uniform for all edges and tips. The material considered is gold, described by a Drude model. The computation makes use of a variable polynomial order, which repartition is based on cell sizes.
Simulation of electromagnetic waves propagation in nano-optics with a high-order discontinuous Galerkin time-domain method