Optical trapping using transverse electromagnetic (TEM)-like mode in a coaxial nanowaveguide

Deterministic Assembly of Single-Emitter Plasmonic Antenna for Ultrahigh Photoluminescence Enhancement

Single-emitter nanoantennas play a crucial role in the fabrication of nanosensors and integrated sources. Since the coupling of single emitter to nanoantennas is largely based on stochastic methods, low qualified rate still hinders a massive deployment. Here, we proposed a deterministic, optical-force-driven method to achieve gap-plasmonic photoluminescence enhancement. Two deterministic steps are carried out in sequence: a composite nanoemitter is first synthesized by linking quantum dots to a silica-rapped gold nanoparticle, followed by an optical delivery of the nanoparticle into a nanoaperture in a gold film. We reason that the nanoparticle-in-nanoaperture (NPiNA) structure efficiently couples out-of-plane excitation light into a gap-plasmon via a transverse electromagnetic mode (TEM)-like transmission mode. An in situ photoluminescence measurement demonstrates a 3× brightness as compared to the nanoparticle-on-mirror (NPoM). This approach paves the way toward deterministic positioning of individual nanoparticles for a wide range of applications on nanophotonics structures on-a-chip.

Nano-optical trapping using an all-dielectric optical fiber supporting a TEM-like mode

Fiber optical tweezers benefit from compact structures and compatibility with fiber optic technology, however, trapping of nano-objects are rarely demonstrated. Here, we predict stable optical trapping of a 30 nm polystyrene particle using an all-dielectric coaxial optical fiber supporting an axisymmetric TEM-like mode. We demonstrate, via comprehensive finite-difference time-domain simulations, that the trapping behavior arises from a significant shift of the fiber-end-fire radiation directivity originated from the nanoparticle-induced symmetry breaking, rather than the gradient force which assumes an invariant optical field. Fabrication of the fiber involved is entirely feasible with existing techniques, such as thermal-drawn and electrospinning, and therefore can be mass-produced.