We report picosecond laser welding of similar and dissimilar materials based on plasma formation induced by a tightly focused beam from a 1030 nm, 10 ps, 400 kHz laser system. Specifically, we demonstrate the welding of fused silica, borosilicate, and sapphire to a range of materials including borosilicate, fused silica, silicon, copper, aluminum, and stainless steel. Dissimilar material welding of glass to aluminum and stainless steel has not been previously reported. Analysis of the borosilicate-to-borosilicate weld strength compares well to those obtained using similar welding systems based on femtosecond lasers. There is, however, a strong requirement to prepare surfaces to a high (10–60 nm Ra) flatness to ensure a successful weld.

Previous reports of ultrafast laser welding of glass-to-glass have indicated that a pre-existing optical contact (or very close to) between the parts to be joined is essential. In this paper, the capability of picosecond laser welding to bridge micron-scale gaps is investigated, and successful welding, without cracking, of two glasses with a pre-existing gap of 3 µm is demonstrated. It is shown that the maximum gap that can be welded is not significantly affected by welding speeds, but is strongly dependent on the laser power and focal position relative to the interface between the materials. Five distinct types of material modification were observed over a range of different powers and surface separations, and a mechanism is proposed to explain the observations.

The fabrication, characterization and encapsulation of a fiber optic temperature sensor based upon a micro Fabry-Perot (F-P) cavity is presented. The F-P cavity is formed between a reflective in-fiber metallic splice and the air-fiber boundary at the end of the sensor. A change in temperature modifies the optical cavity length, and this is observed as a change in the reflected interference spectrum. The sensor has been demonstrated for high-temperature measurement up to 1100 °C. The stability of the sensor system is ~10 °C over a period exceeding 300 h at 1100 °C. Furthermore, a sealed capillary is used as a protective enclosure.

We report systematic analysis and comparison of ps-laser microwelding of industry relevant Al6082 parts to ${\mathrm{SiO}}_2$ and BK7. Parameter mapping of pulse energy and focal depth on the weld strength is presented. The welding process was found to be strongly dependent on the focal plane but has a large tolerance to variation in pulse energy. Accelerated lifetime tests by thermal cycling from $-50°$ to $+90°\mathrm{C}$ are presented. Welds in Al6082-BK7 parts survive over the full temperature range where the ratio of thermal expansion coefficients is 3.4:1. Welds in $\mathrm{Al}6082\text{-}{\mathrm{SiO}}_2$ parts (ratio 47.1:1) survive only a limited temperature range.

Conventional manufacturing of microfluidic devices from glass substrates is a complex, multi-step process that involves different fabrication techniques and tools. Hence, it is time-consuming and expensive, in particular for the prototyping of microfluidic devices in low quantities. This article describes a laser-based process that enables the rapid manufacturing of enclosed micro-structures by laser micromachining and microwelding of two 1.1-mm-thick borosilicate glass plates. The fabrication process was carried out only with a picosecond laser (Trumpf TruMicro 5×50) that was used for: (a) the generation of microfluidic patterns on glass, (b) the drilling of inlet/outlet ports into the material, and (c) the bonding of two glass plates together in order to enclose the laser-generated microstructures. Using this manufacturing approach, a fully-functional microfluidic device can be fabricated in less than two hours. Initial fluid flow experiments proved that the laser-generated microstructures are completely sealed; thus, they show a potential use in many industrial and scientific areas. This includes geological and petroleum engineering research, where such microfluidic devices can be used to investigate single-phase and multi-phase flow of various fluids (such as brine, oil, and CO₂) in porous media.