Characteristics of laser absorption and welding in FOTURAN glass by ultrashort laser pulses

Abstract

The nonlinear absorptivity of FOTURAN glass to ultrashort laser pulses is evaluated by experimental measurement and thermal conduction model at different parameters including energy and repetition rate of the laser pulse, translation speed and thermal properties of the sample. The mechanical strength of an embedded laser-melted sample and an overlapped weld sample is determined by a three-point-bending test and a shear test, respectively. The results are related to the average absorbed laser power Wab. We found the mechanical strength of an overlapped weld joint to be as high as that of the base material for low Wab, if the sample pair is pre-bonded to provide optical contact.

Characterization of Plasma in Microwelding of Glass Using Ultrashort Laser Pulse at High Pulse Repetition Rates

“…The cross-section shows a dual-structure [14,16] consisting of a teardrop-shaped inner structure and an elliptical outer structure. Thermal conduction model [2,14,16] indicates that the laser energy is absorbed in the inner structure, and that the glass is melted in the outer structure, where working temperature with a viscosity of 10 4 dPas is reached. The dualstructure is also clearly observed in the side view (Fig.…”

“…where photo , casc and rec are coefficient of photoionization, cascade ionization and recombination of free-electrons, respectively, k is photon number for MPI given by where E g is band gap energy and indicates the integer part within it, and I(t) is laser irradiance given by (2) p is duration of the laser pulse. The cascade ionization coefficient casc is given by [10] ( 3) where is the time between collision for inverse Bremsstrahlung, c the vacuum speed of light, n 0 the refractive index of the medium at laser-frequency , m electron mass, M molecular mass, 0 vacuum permittivity, and the effective ionization potential.…”

“…Internal modification of transparent material using ultrashort laser pulse (USLP) has attracted much attention due to interesting applications such as microwelding [1][2][3], waveguide formation [4,5], selective etching [6] and so on. Among these applications, microwelding of glass using USLP is considered to be especially promising, since crackfree welding with monolithic structure having high mechanical strength is available even with glass having high thermal expansion coefficient.…”

[INVITED] Ultrafast laser micro-processing of transparent material

“…The laser micro-processing techniques using burst pulses [92,93] or double pulses [94] enhance the efficiency of laser processing and welding and also provide the high controllability. The novel idea of the prebonding drastically improved the joining strength and reliability of ultrafast laser micro-welding [95,96]. Miyamoto further clarified the crackfree condition that is related to the dual-structure of the processed area [97,98].…”

Compact Infrared/Visible Laser Transmitter Featuring an Extended Detectable Trajectory

“…Long-and short-distance delivery of highly defined light beams has played a central role in a variety of applications, such as free-space-optics-based communications, laser-assisted welding and surgery, and military/leisure training systems [1][2][3]. In particular, cost effective military training systems, such as multiple integrated laser engagement system (MILES), are known to require a long-reach infrared (IR) laser transmitter, which acts as a projectile in simulated combat [4].…”