Structural modifications of ZnO single crystals that were created by the irradiation with femtosecond laser pulses at fluences far above the ablation threshold were investigated with micro-Raman spectroscopy. After light-matter interaction on the femtosecond time scale, rapid cooling and the pronounced thermal expansion anisotropy of ZnO are likely to cause residual strains of up to 1.8% and also result in the formation of surface cracks. This process relaxes the strain only partially and a strained surface layer remains. Our findings demonstrate the significant role of thermoelastic effects for the irradiation of solids with intense femtosecond laser pulses.
- strain measurement
Schneider, A., Wolverson, D., Sebald, K., Hodges, C., Kuball, M., & Voss, T. (2013). Analysis of strained surface layers of ZnO single crystals after irradiation with intense femtosecond laser pulses. Applied Physics Letters, 102, . https://doi.org/10.1063/1.4807923