Department of Physics2024-11-0920161880-068810.2961/jlmn.2016.03.00122-s2.0-84994593712http://dx.doi.org/10.2961/jlmn.2016.03.0012https://hdl.handle.net/20.500.14288/10999We investigated modifications and the temporal evolution of the morphology in the photoexcited region inside diamond single crystal after photoexcitation by tightly focused fs laser pulses. We found that double-pulse irradiation with 200-400 fs laser pulses was able to induce a permanent modification in the photoexcited region, while single-pulse irradiation with 100-300 fs laser pulses was not. The modification by double-pulse irradiation became larger for a longer time-difference between the two pulses in the range from 1 ps to 10 ps. The morphology change observed by a pump-probe optical microscope showed that the photoexcited region by double-pulse irradiation was smaller than by single-pulse irradiation, even for the same total pulse energy, with the amplitudes of the laser induced-stress waves being the same. This observation suggests that the photoinduced plasmas by double-pulse irradiation was localized in a smaller region than that by single-pulse irradiation, and the difference in plasma distribution could be the origin of the permanent modification.NanoscienceNanotechnologyMaterials sciencesMultidisciplinary design optimizationOpticsPhysics,Journal Article3866527000127613