To realize the ultrahigh intensity over 10^23 W/cm^2, we carried out the wavefront correction and tight focusing of the CoReLS petawatt laser. By the wavefront correction and tight focusing of the CoReLS petawatt laser with two-stage adaptive optics systems and an f/1.1 (f=300 mm) off-axis parabolic mirror, we obtained a near-diffraction-limited focal spot. The measured peak intensity was (1.1±0.1)×10^23 W/cm2, the first realization of the laser intensity over 10^23 W/cm^2. With the PW laser of intensity over 10^23 W/cm^2, we plan to explore strong field QED phenomena and proton/ion acceleration dominated by the RPA mechanism.
In this paper, we demonstrate the formation of self-organized periodic nanogratings on the titanium surface under the
irradiation of a single-beam femtosecond laser. We vary various laser parameters such as the laser fluence and the
number of laser pulses in each spot to fabricate self-organized nanogratings on the titanium surface. We investigate that
the direction of the nanogratings is perpendicular to the direction of laser polarization. We also report on the dependence
of the nanogratings' period, produced on titanium surface, on the laser fluence and the number of irradiated laser pulses
in each spot. Nanogratings' period show increasing trend with the increase of the laser fluence, whereas show decreasing
trend with the increase of the number of applied laser pulses. Furthermore, we briefly explain the formation mechanism
of the self-organized periodic nanogratings, produced on the titanium surface. The reasons behind the dependence of
nanogratings' period on the laser fluence and the number of laser pulses are explained as well. The self-organized
nanogratings are mainly produced due to the interaction of the
high-intensity incident laser beam and the laser induced
plasma waves. Above certain threshold energy, phase explosion takes place, which in turn causes the formation of selforganized
nanogratings on the titanium surface.
This paper reports on the colorizing of the stainless steel surface by controlling the irradiation conditions of a single-beam
femtosecond laser. We change the color of the stainless steel surface by femtosecond laser induced periodic self-organized
nanogratings or microgratings on the sample surface. Colorizing of metal surface by periodic microholes,
produced by femtosecond laser, is achieved for the first time. The laser modified stainless steel surfaces show different
colors under different incident or azimuthal angles of the incident light, which changes in color indicate the dependence
of the metal color on the angles (incident and azimuthal) of the incident light. We report, for the first time, the changes
of metal color due to the change of the azimuthal angles of the incident light. Furthermore, the changes in the color of
the laser modified metal surfaces are mainly due to the excitation of surface plasmon polaritons (SPPs) on the metal
surface. The resonant angle of SPPs is different for different wavelength of light. As a result, under different incident or
azimuthal angles different wavelength of light is trapped on the surface depending on the resonance for that particular
wavelength; light of other wavelengths react naturally and contributes for the color change of the stainless steel surfaces.
Finally, we discovered that the nanostructures produced inside the self-organized nanogratings and microholes play
important roles for the propagation of the SPPs in parallel with the nanogratings and mcroholes, which nanostructures
are responsible for a complex SPPs excitation on the sample surface.
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