Microsphere array assisted laser nanofabrication

The key challenge of laser nanoprocessing is how to focus the ultraviolet or visible laser beam in the air to sub-100nm, thereby overcoming the optical diffraction limit. Our research shows that the transparent microsphere array formed by self-arrangement or large-area rotation coating can separate the incident laser beam into millions of tiny beams, and can also be used as a lens to focus these tiny beams for surface nano-mapping. The local light density is greatly enhanced, and the sample is processed in parallel mode. This technology uses the usual two-dimensional (2D) microsphere array to focus the incident laser beam on the substrate. Therefore, only a few laser radiation pulses can be used to generate millions of images on the substrate using a single-step surface mapping method. Sub-micron holes. After laser nano-processing, the microspheres can be removed using traditional ultrasonic cleaning. Flexible control of the scanning shape of the laser beam can form a complex nanostructure design. Laser Interference Lithography (Laser Interference Lithography, LIL) is a powerful tool for forming large-area periodic nanostructures (such as nanodots or nanowire arrays) in a short time. It only takes a few minutes of exposure to ultraviolet light, and then adopts photoresistance and chemical etching or stripping process, that is, plasma nanostructures can be formed on the metal film. The coherence length of the laser beam is a key factor in the interference of two beams in a large area (centimeter level). One laser irradiation forms a nano-linear array, and after rotating the sample 90°, another laser irradiation is used to form a nano-dot array. By controlling the irradiation time and the irradiation scheme, various nanostructures can be formed, with shapes ranging from rectangles to triangles and ellipses. The 2D nanostructure formed by the photoresist layer can also be transferred to the substrate by chemical etching to form a 2.5D nanostructure.