Direct welding of fused silica with femtosecond fiber laser

Abstract

Development of techniques for joining and welding materials on a micrometer scale is of great importance in a number of applications, including life science, sensing, optoelectronics and MEMS packaging. In this paper, methods of welding and sealing optically transparent materials using a femtosecond fiber laser (1 MHz & 1030 nm) were demonstrated which overcome the limit of small area welding of optical materials from previous work. When fs laser pulses are tightly focused at the interface of the materials, localized heat accumulation based on nonlinear absorption and quenching occur around the focal volume, which melts and resolidifies, thus welds the materials without inserting an intermediate layer.The welding process does not need any preprocessing before the welding. At first, single line welding results with different laser parameters was studied. Then successful bonding between fused silica with multi line scanning method was introduced. Finally, complete sealing of transparent materials with fs laser was demonstrated. Scanning electron microscopy (SEM) images of the sample prove successful welding without voids or cracks. This laser micro-welding technique can be extended to welding of semiconductor materials and has potential for various applications, such as optoelectronic devices and MEMS system.

Processing of Single-Walled Carbon Nanotubes with Femtosecond Laser Pulses

“…Further analysis of the experimental settings was performed to find the optical properties of the samples for joining. For the current experiments, the spot size (D) of the laser beam was calculated using the following equation, as described in the literature [33]:…”

“…where λ is the laser wavelength and N.A is the numerical aperture values of the objective lens. Thereafter, the average fluence was estimated by employing the following equation [33]: = * * where E is the energy of single pulse, F is the frequency of laser pulses, i.e., repetition rate, and v is the laser scan speed.…”

Femtosecond fiber laser welding of PMMA

“…Transmission measurements of the laser light allowed directly estimating the absorption through the sample ( = 8.9 • 10 ). Assuming for PMMA a thermal conductivity = 0.19W m −1 K −1 and a thermal diffusivity = 1.09 • 10 m 2 s -1 [14], the temperature growth of the substrate (ΔT 1 = 4.6×10 -3 °C ) after each laser pulse was calculated by Eq. (1).…”

“…Femtosecond laser processing of transparent materials, such as glasses, polymers, and crystals [1], has become a microfabrication technique of growing interest in several fields, particularly for the production of photonic and bio-medical devices since it allows direct fabrication of waveguides [2][3][4], gratings [5][6][7] and microfluidic channels [8][9][10][11][12][13].Based on this technology, several studies have demonstrated the ability of focused femtosecond laser pulses to weld similar [14,15] and dissimilar glasses [16][17][18] without the insertion of any intermediate light-absorbing layer. This innovative laser joining technique promises an easy and versatile integration of miniaturized devices.…”

Surface plasmon resonance assisted rapid laser joining of glass

“…1 In particular, direct joining techniques of glass with a focused ultra-short (femtosecond) pulsed laser beam have recently been reported. [2][3][4][5][6][7][8] In these studies, by focusing the ultra-short laser pulses at the interface between the glass substrates, the nonlinear absorption of the beam has been exploited and glass joint strength of 14.9 MPa was reported. 4 However, there are a number of shortcomings associated with this technique.…”