Improved Nano-optical Traps for Single-particle Sensing Applications

Computational design of nanoantennas with improved power enhancement capabilities via shape optimization

“…Nanoantennas—structures fabricated in nanometer scales and used in diverse nanooptical applications—have become increasingly important in the scientific and technical literature, in parallel to advances in nanotechnology 1 – 38 As opposed to the traditional antennas used at radio and microwave frequencies, nanoantennas can be described, in terms of working principles, as small antennas that operate at THz and optical frequencies. In this perspective, a nanoantenna that operates as a receiver can gather electromagnetic waves at optical frequencies and direct them to its terminals, enabling optical energy harvesting.…”

“…Similarly, a nanoantenna operating as a transmitter makes it possible to detect nearby particles (e.g., located in its terminal) from far zone, which can be useful in a plethora of applications, such as bio-sensing. Although most (particularly earlier) studies on nanoantennas have investigated relatively simple geometries, such as bowtie, 1 , 2 , 8 , 10 monopole/dipole, 4 , 6 , 12 , 23 , 28 disk (or its inversion, i.e., hole), 7 , 38 sphere, 16 as well as their arrays (e.g., Yagi-Uda structures), 11 , 13 , 15 , 22 , 24 , 25 , 36 , 37 mainly considering restrictions in experimental setups, relatively complex shapes (e.g., fractal, 3 cross-shaped, 21 flower-shaped, 26 spiral, 27 horn-shaped, 31 tapered, 33 log-periodic, 34 , 35 and combinations with other nanostructures 32 ) have also been studied. In fact, besides the basic material, 19 , 20 geometry is one of the most important factors for the performance of a nanoantenna, 29 and new advances in nanoscale fabrication techniques encourage researchers to resort alternative shapes, which can demonstrate desired capabilities (in terms of bandwidth, directivity, field enhancement, etc.)…”