Glass-in-glass infiltration for 3D micro-optical composite components.

Chalcogenide glass exhibits a wide transmission window in the infrared range, a high refractive index, and nonlinear optical properties; however, due to its poor mechanical properties and low chemical and environmental stability, producing three-dimensional microstructures of chalcogenide glass remains a challenge. Here, we combine the fabrication of arbitrarily shaped three-dimensional cavities within fused silica molds by means of femtosecond laser-assisted chemical etching with the pressure-assisted infiltration of a chalcogenide glass into the resulting carved silica mold structures. This process enables the fabrication of 3D, geometrically complex, chalcogenide-silica micro-glass composites. The resulting products feature a high refractive index contrast that enables total-internal-reflection guiding and an optical quality roughness level suited for applications in the infrared.

Few pulses femtosecond laser exposure for high efficiency 3D glass micromachining.

Advanced three-dimensional manufacturing techniques are triggering new paradigms in the way we design and produce sophisticated parts on demand. Yet, to fully unravel its potential, a few limitations have to be overcome, one of them being the realization of high-aspect-ratio structures of arbitrary shapes at sufficiently high resolution and scalability. Among the most promising advanced manufacturing methods that emerged recently is the use of optical non-linear absorption effects, and in particular, its implementation in 3D printing of glass based on femtosecond laser exposure combined with chemical etching. Here, we optimize both laser and chemical processes to achieve unprecedented aspect ratio levels. We further show how the formation of pre-cursor laser-induced defects in the glass matrix plays a key role in etching selectivity. In particular, we demonstrate that there is an optimal energy dose, an order of magnitude smaller than the currently used ones, yielding to higher process efficiency and lower processing time. This research, in addition to a conspicuous technological advancement, unravels key mechanisms in laser-matter interactions essential in chemically-based glass manufacturing and offers an environmentally-friendly pathway through the use of less-dangerous etchants, replacing the commonly used hydrofluoric acid.

Vibration monitoring based on optical sensing of mechanical nonlinearities in glass suspended waveguides.

Vibration monitoring plays a key role in numerous applications, including machinery predictive maintenance, shock detection, space applications, packaging-integrity monitoring and mining. Here, we investigate mechanical nonlinearities inherently present in suspended glass waveguides as a means for optically retrieving key vibration pattern information. The principle is to use optical phase changes in a coherent light signal travelling through the suspended glass waveguide to measure both optical path elongation and stress build-up caused by a given vibration state. Due to the intrinsic non-linear mechanical properties of double-clamped beams, we show that this information not only offers a means for detecting excessive vibrations but also allows for identifying specific vibration patterns, such as positive or negative chirp, without the need for any additional signal processing. In addition, the manufacturing process based on femtosecond laser exposure and chemical etching makes this sensing principle not only simple, compact and robust to harsh environments but also scalable to a broad frequency range.