Plastic residual strains under femtosecond laser microexplosion initiated high pressure inside quartz

Femtosecond laser microexplosion can take high pressure to materials, which facilitates strain investigation in laboratory. In this paper, nanoindentation was utilised to measure plastic residual strains around femtosecond laser microexploded zone. Optical waveguides was microexploded by femtosecond laser pulses just below the back sub-surface of a quartz wafer. Nanomechanical properties of the surface area that just are above the optical waveguides were measured. Load dependent changes in hardness can be found from nanoindentation experiments. Using the formula correlating residual strains with hardness values measured by nanoindentation, plastic residual strains in the surrounding area of femtosecond laser microexploded optical waveguide was acquired. The variations in plastic residual strains facilitated the investigation of refractive index changes in the area about femtosecond microexploded zone.