Local Melting of Gold Thin Films by Femtosecond Laser-Interference Processing to Generate Nanoparticles on a Source Target

Abstract

Shape- and size-controlled metallic nanoparticles are very important due to their wide applicability. Such particles have been fabricated by chemosynthesis, chemical-vapor deposition, and laser processing. Pulsed-laser deposition and laser-induced dot transfer use ejections of molten layers and solid-liquid-solid processes to fabricate nanoparticles with a radius of some tens to hundreds of nm. In these processes, the nanoparticles are collected on an acceptor substrate. In the present experiment, we used laser-interference processing of gold thin films, which deposited nanoparticles directly on the source thin film with a yield ratio. A typical nanoparticle had roundness fr=0.99 and circularity fcirc=0.869, and the radius was controllable between 69 and 188 nm. The smallest radius was 82 nm on average, and the smallest standard deviation was 3 nm. The simplicity, high yield, and ideal features of the nanoparticles produced by this method will broaden the range of applications of nanoparticles in fields such as plasmonics.

Laser-Induced Transfer of Noble Metal Nanodots with Femtosecond Laser-Interference Processing

“…On the other hand, the nanodots fabricated using LIDOS with an Au thin film, in which nanodots are deposited on a source target placed in air as seen in Figure 1 a, have a smaller average particle size of less than 200 nm. This is probably due to the fact that the interference pattern period is 1.93 μμm, which is about half that of the present study [ 18 ]. It is important to note that for precise comparison, it is necessary to prepare the same experimental systems.…”

“…It is important to note that for precise comparison, it is necessary to prepare the same experimental systems. The smallest standard deviation in LIDOS was 3 nm [ 18 ], which is far smaller than the values shown in Table 1 . With even larger spot sizes, higher pulse energies, and thicker film targets, the deposit becomes a micron-sized dot or larger diameter film structure, and this process is called LIFT [ 1 , 2 , 3 , 4 , 5 , 21 ].…”

“… ( a ) Schematic illustration of laser-induced forward transfer (LIFT), laser-induced dot transfer (LIDT), and the laser-induced dot caught on source target (LIDOS) [ 18 ] process. ( b ) LIDT with interference pattern [ 17 ].…”

Direct and High-Throughput Fabrication of Mie-Resonant MetasurfacesviaSingle-Pulse Laser Interference

“…To overcome this limitation and obtain high-throughput and cost-effectiveness, we propose the application of direct laser interference patterning. Direct patterning using high-peak-power laser interference has been previously shown as a suitable tool for large-area microstructuring of metals, [30][31][32][33][34][35][36][37][38][39] organic materials, [40][41][42] and even Si. [43][44][45][46][47][48][49][50] It does not require resist, etching or any other post-processing steps, thus is relatively fast and simple.…”

“…Direct patterning using high-peak-power laser interference has been previously shown as a suitable tool for large-area microstructuring of metals, − organic materials, − and even Si. − It does not require resist, etching, or any other postprocessing steps, thus is relatively fast and simple. Although direct laser interference patterning has been used to achieve submicrometer resolution, as shown in the case of bulk Si, , the technique has never been exploited to obtain high-index metasurfaces.…”