@article{oai:repo.qst.go.jp:00079042,
 author = {Otobe, Tomohito and Tomohito, Otobe},
 journal = {Physical Review Applied},
 month = {Feb},
 note = {We report a first-principle calculation for the wavelength-dependence of a laser excitation process on a silicon surface.
Although  lower frequency laser is reflected by a lower density plasma, 
it can penetrate thicker plasma sheet. 
Therefore, the depth of the laser processing depends on the width of the plasma at the surface and laser wavelength. 
The time-dependent density-functional theory and Maxwell’s equations are simultaneously employed to elucidate the effect of laser propagation on laser-matter interaction under ultrafast pulse lasers (FWHM:12 fs).
A longer-wavelength laser field facilitates deeper melting and ablation in silicon, despite a lower critical plasma density. 
Such a deeper excitation by a longer wavelength is because of the penetration of the laser field through the plasma on the surface. 
The plasma-formation depth is saturated at approximately half the wavelength in silicon.},
 pages = {024062-1--024062-6},
 title = {Wavelength Dependence of the Laser-Excitation Process on a Silicon Surface},
 volume = {13},
 year = {2020}
}