Extended transport and size selection of gold-nanorods using a liquid-immersible all-fiber Airy-like beam

Gold nanorods (AuNRs) offer a number of opportunities across fields such as imaging, biosensing, and cancer therapy. Their rich interaction with light can lead to selective heating and also manipulation through the use of optical forces. Here, we report the first demonstration of longitudinal surface plasmon resonance based selective optical transport of AuNRs with a diameter of 40 nm and lengths of up to 180 nm. This is performed in a single ∼ 40 μL D₂O droplet using a propagation invariant fiber generated Airy-like beam. The resulting ultracompact platform reduces the interaction volume by 7 orders of magnitude compared to bulk-optic beam-shaping systems. AuNRs of aspect ratio between 2.3 and 4.5 were dispersed in droplet. At a wavelength of 976 nm, near-resonant AuNRs with an aspect ratio of 4.5 undergo curvilinear transport along the main lobe of the Airy-like field over a distance of ∼500 μm, whereas off-resonant nanorods remain virtually immobile. This plasmon-resonance-enhanced selectivity enables real-time, morphology-dependent manipulation and sorting of nanorods. Our observations are supported by finite element simulations, providing strong theoretical validation of our experimental observations.