Long range nanostructuring of silicon surfaces by photonic nanojets from microsphere Langmuir films

Ultra-high ordered, centimeter scale preparation of microsphere Langmuir films

“…In recent work, we have shown that such monolayers are compatible with photonic applications [34,35], and in this paper we present results and discuss on monolayer quality improvement. An important point in this paper is to highlight the utility of such monolayers with ease preparation and high coverage ratio, over large area and with high stability, reliable for the final laser engineered photonic structures and throughout the overall fabrication process.…”

“…The LB technique provides one of the few methods of preparing organized assemblies of monolayers, which are prerequisite in various applications where high-accuracy spatially resolved methods are needed [33]. Such monolayers made with transparent microspheres find applications in the structuration of bulk substrates, resulting in either nanohole or nanobump arrays [34][35][36][37][38][39], but have also been explored in the literature in the context of electronics, optics, microlithography, chemical sensors, and biosensors [32][33][34][35][36][37][38][39][40][41]. It has been demonstrated that properly coated nanoparticles can be organized at the air-water interface by using the same procedure.…”

“…However, one must be aware that the coating/ functionalization of the nanoparticles is an important factor in the ability of such particles to form high quality monolayers. If their hydrophobicity is too low, the particles float randomly at the surface of water or sink (if density is higher than that of water), whereas the particles tend to stick to unwanted aggregates if the coating is too hydrophobic [34,36]. Solid to super-liquid phase transitions in Langmuir monolayers are related to the long-range repulsive interactions in the case of molecules, by stabilizing the undulating phases at thermodynamic equilibrium.…”

“…In our earlier works [34,35], we adopted the standard protocol of LB film preparation and the obtained monolayers exhibit nearly 60% coverage ratio, at a surface pressure of 15 mN/m and 10 mm/min compression rate as the substrates were evidently not completely void free. The best results obtained by the standard protocol reveal the limit on what can be achieved for the preparation of microsphere monolayers when the operation a LB system relies only on surface tension measurements.…”

Laser micro machining beyond the diffraction limit using a photonic nanojet

“…However, some groups have reported performing laser micromachining using a PNJ under the condition that the microspheres are arrayed on the sample surface [13][14][15]. In these studies, the variation in the machining diameter and depth was investigated by fluence control of the incident laser.…”