Ultrafast microwelding of glass by selective absorption of a continuous-wave laser into excited electrons

Glass-to-glass welding using ultrashort pulse laser is attracting attention. However, the low processing speed and the requirement of the small air gap between glass substrates have impeded its use in industry. In our study, we achieved rapid welding of glass substrates by coaxially focusing a single femtosecond laser pulse and a continuous-wave (CW) laser with a wavelength that transmits through glass. The selective absorption of the CW laser into the excited electrons increased the processing speed by a factor of 500 compared to the conventional method, while the allowable gap increased by a factor of 4.