Hiroki Mashiko

Focusing coherent soft-x-ray radiation to a micrometer spot size with an intensity of 10 14 W/cm 2

We investigate the focusability of intense coherent soft-x-ray radiation generated by high-order harmonic conversion. The 27th-harmonic wave at 29.6 nm is focused by an off-axis parabolic mirror with a SiC/Mg multilayer coating. Focal-spot images are observed from the visible fluorescence induced by the soft-x-ray photons on a Ce:YAG scintillator. We demonstrate focusing of the soft-x-ray beam to a 1-microm spot size with a peak intensity of 1 x 10(14) W/cm2, which is to our knowledge the highest ever reported in the soft-x-ray region.

Focusing multiple high-order harmonics in the extreme-ultraviolet and soft-x-ray regions by a platinum-coated ellipsoidal mirror

The focusability of multiple high-order harmonics in the extreme-ultraviolet and soft-x-ray regions is described, together with the design and performance of the ellipsoidal mirror used for this purpose. The mirror focuses intense coherent light in the spectral-region from 25 to 40 nm into a 2.4 microm spot size with a focused peak intensity of 6 x 10(13) W/cm2. The focal images indicate that a good beam profile is obtained with a near-Gaussian distribution and a beam quality factor (M2 value) as low as 2.4.

Focusing Intense High-Order Harmonics to a Micron Spot Size

The focusability of intense coherent radiation generated by high-order harmonic conversion is investigated. A variety of focusing mirrors are tested and used in the focusing experiments. We demonstrate the focusing of an extremeultraviolet/soft X-ray beam to a 1 µm spot size with a peak intensity as high as 1 × 1014 W/cm2, which is sufficient to stimulate nonlinear optical phenomena in the short wavelength region.

Focusing of soft-x-ray high-order harmonics and ablation of metal surface

We have observed ablation patterns on metal surfaces made by focusing high-order harmonics in the soft-X-ray region. The ablation processes are investigated from the intensity dependence.

Development of grazing-incidence focusing system for high-order harmonics in the soft X-ray region

We have developed grazing-incidence focusing system for high-order harmonics in soft X-ray region using Pt-coated ellipsoidal mirror. The practicability of mirror was confirmed by investigating characteristics for focused beam profile, reflectivity, and estimating focused intensity.

Generation of strong soft x-ray field based on high-order harmonics

We have generated a strong soft x-ray field based on high-order harmonics. The 27th harmonic wave was selected and focused to a spot size of less than 1 μm using a Si beam splitter and an off-axis parabolic mirror. The highest intensity achieved at 29.6 nm was 1 × 1014 W/cm2.