Single-Step Plasmonic Dimer Printing by Gold Nanorod Splitting with Light

Abstract

Optical printing is a flexible strategy to precisely pattern plasmonic nanoparticles for the realization of nanophotonic devices. However, the generation of strongly coupled plasmonic dimers by sequential particle printing can be a challenge. Here, we report an approach to generate and pattern dimer nanoantennas in a single step by optical splitting of individual gold nanorods with laser light. We show that the two particles that constitute the dimer can be separated by sub-nanometer distances. The nanorod splitting process is explained by a combination of plasmonic heating, surface tension, optical forces, and inhomogeneous hydrodynamic pressure introduced by a focused laser beam. This realization of optical dimer formation and printing from a single nanorod provides a means for dimer patterning with high accuracy for nanophotonic applications.

Thin-Film-Assisted Photothermal Deformation of Gold Nanoparticles: A Facile and In-Situ Strategy for Single-Plate-Based Devices

“…However, thicker TiO 2 films also present higher melting temperature and larger viscosity, which introduces great difficulty in the thermal diffusion and the dragging of the Au droplet above. Therefore, only elongation of Au NP was observed as shown previously. − …”

“…Although a paradigm shift of on-chip synthesis has significantly improved the controllability of single-crystal nanoplates with arbitrary size, shape, composition, and regularity, it still heavily relies on wet chemistry − and self-assembly, , which could lead to surface contamination with limited local selectivity and device compatibility. Direct on-chip transformation of single Au NPs without using any wet chemistry is possible with laser irradiation, which is based on the synergy of photothermal and optical force effect. − However, the deformation of the Au NP mostly leads to dome-like and rod-like shapes due to the large surface tension of molten Au droplet, which significantly limits their application as 2D nanoplates. Thus, direct transformation of Au NP to nanoplate via a photothermal effect is challenging and yet realized.…”

Robotic Nanomanipulation Based on Spatiotemporal Modulation of Optical Gradients

“…The development and integration of robotic manipulation inside a real-time imaging and characterization platform facilitate a wide range of applications in nanophotonics, nanoelectronics, and biomedicine. − Among various manipulation techniques, − optical tweezers have attracted considerable attentions for their capacity of controlling the position and orientation of single free-standing nanostructures − (e.g., nanorod and nanowire) and selective deposition (i.e., direct laser printing) of these nanostructures in targeted positions with high precision. − Equipped with a feedback-controlled interface, optical tweezers can be turned into a versatile robotic manipulation platform, which is highly desirable for the development of optical manipulation combined with microscopy/spectroscopy. ,, Specifically, unlike automated manipulation, which demands sophisticated algorithms for planning, decision-making, and fault-tolerance handling, human-in-the-loop control proves to be equally compelling, particularly in scenarios that necessitate substantial human involvement; for example, optical manipulation of functional NPs for active drug delivery and nanosurgery in complex fluidic environments, e.g., blood vessels and neural network. Customizable route planning through a human–machine interface (HMI) is more feasible. − …”

“…Conventional HMIs rely on utilizing intensity gradient force for micromanipulation, yet the intensity noise that strongly deteriorates the manipulation of NPs is almost inevitable. Therefore, nearly all robotic nanomanipulations have been based on well-defined optical beams. − Specifically, they relied on tunable intensity gradient forces for capture-and-print assembly by controlling the laser power. − The increment of laser power improves the speed of the manipulation, yet it decreases the precision dramatically due to the detrimental effect of laser noise and thermal impact. An alternative strategy to broaden the scope of HMI for versatile manipulations is tailoring the phase gradient of light. − However, the universality of manipulation is largely hampered by the control interface with preassigned tasks.…”