FINITE-BOUNDARY BOWTIE APERTURE ANTENNA FOR TRAPPING NANOPARTICLES

We have found that a single finite-boundary bowtie aperture (FBBA) antenna with gap separation of 10 nm between its tips is capable of confining the electric field to a 18 nm X 18 nm region (λ/39.4) and enhancing its near-field intensity by 365-fold at 5 nm beneath the gold film enhancing its near-field intensity by 1, 800-fold inside the gap. The FBBA antenna is thus able to provide enhanced trapping potential by virtue of such extraordinarily high (but exponentially decaying) optical near-fields. We have been able to show that 12 nm gold nanoparticles can, in principle, be trapped by the FBBA antenna with 20 nm gap separation; stable trapping is assured where the trapping potential is found to be several times higher than Brownian-motion potential in water. In addition to trapping nanoparticles, this simple but efficient FBBA antenna may find ready application in near-field optical data storage.