General Strategy toward Dual-Scale-Controlled Metallic Micro–Nano Hybrid Structures with Ultralow Reflectance

Abstract

Functional metal surfaces with minimum optical reflection over a broadband spectrum have essential importance for optical and optoelectronic devices. However, the intrinsically large optical impedance mismatch between metals and the free space causes a huge obstacle in achieving such a purpose. We propose and experimentally demonstrate a general pulse injection controlled ultrafast laser direct writing strategy for fabricating highly effective antireflection structures on metal surfaces. The presented strategy can implement separate and flexible modifications on both microscale frame structures and nanoscale particles, a benefit from which is that optimized geometrical light trapping and enhanced effective medium effect reducing the surface reflection can be simultaneously achieved within one hybrid structure. Thus, comprehensively improved antireflection performances can be realized. Hybrid structures with substantial nanoparticles hierarchically attached on regularly arrayed microcones are generally constructed on different metal surfaces, achieving highly efficient light absorption over ultraviolet to near-infrared broadband spectrum regions. Reflectance minimums of 1.4%, 0.29%, and 2.5% are reached on Cu, Ti, and W surfaces, respectively. The presented strategy is simple in process, adaptable for different kinds of metals, reproduceable in dual-scale structural features, and feasible for large-area production. All these advantages make the strategy as well as the prepared antireflection structures excellent candidates for practical applications.

Laser welding of laser-structured copper connectors for battery applications and power electronics

“…These particles can also contribute to an increase in absorption. If the focal diameter is significantly larger than the path distance, random coral-like structures are formed [19,20].…”

“…The shape and dimension of the structures and in particular the depth have a great influence on the absorption properties of the resulting surface. It has already been shown that this effect is not limited to a discrete wavelength spectrum, but affects all wavelengths from ultraviolet (~250 nm) to the near infrared (~2500 nm) [19][20][21].…”

Design and Fabrication of Dual-Scale Broadband Antireflective Structures on Metal Surfaces by Using Nanosecond and Femtosecond Lasers

“…Several techniques for fabricating micro-or nanostructures have been proposed, such as chemical etching [17], coating [18], reactive ion etching [19], and pulsed laser processing [20,21]. The chemical etching method is one of the most widely used techniques; it uses chemical etchants to etch the surface of the materials to form a rough surface, but there is poor control over the shape of the structures.…”

Improving the Energy Conversion Efficiency of a Laser-Driven Flyer by an In Situ-Fabricated Nano-absorption Layer

“…Lee et al [19] reported a design strategy to achieve a robust platform for plasmonenhanced light harvesting using aluminum core-shell nanostructures, which resulted in a remarkable increase in photo-to-chemical conversion. Fan et al [20] demonstrated an ultrafast laser-processing strategy for fabricating highly effective antireflection micro-nano-structures on thick metal surfaces, and an average reflectance of 4.1%, 2.4%, and 3.2% in the broadband spectrum from ultraviolet to near-infrared on Cu, Ti, and W, respectively, surfaces were achieved. However, to our best knowledge, there is no research on using nanostructured material to improve the laser absorption in LDFs.…”