A method for characterising residual strains around femtosecond laser microexploded waveguide by nanoindentation

Abstract

In this paper, quartz wafer was microexploded by a commercial Ti: Sapphire regenerative amplifier (spectra physics, spitfire). And nanomechanical properties of the surface area that just above the laser induced waveguide were measured by a commercial nanomechanical test system (nano indenter XP, MTS Inc.). Indentation depth dependent changes in hardness can be found from nanoindentation experiments, which reflected the variations in plastic residual strains. Using the formula brought out in our previous work that correlate residual strains with hardness values measured by nanoindentation, the indentation depth dependent distribution of plastic residual strains in the area above femtosecond laser microexploded optical waveguide was explored. The mean plastic residual strains decreased from 0.048 to 0.01 in the indentation depth of 200 nm~700 nm, and kept to be 0.01 when the indentation depth was larger than 700 nm.