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Eiji J. Takahashi
PhysicsHarmonicAtomic physicsHarmonicsHigh harmonic generation
8Publications
7H-index
573Citations
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Publications 8
Newest
#1Tsuneto KanaiH-Index: 20
#2Eiji J. TakahashiH-Index: 7
Last. Katsumi MidorikawaH-Index: 49
view all 4 authors...
52 CitationsSource
#1Hiroshi HasegawaH-Index: 18
#2Eiji J. TakahashiH-Index: 7
Last. Katsumi MidorikawaH-Index: 49
view all 5 authors...
We report on the multiphoton ionization processes in the soft-x-ray region ({lambda}{<=}30 nm). On the basis of the measured time-of-flight spectra for both ions and electrons obtained using intense soft-x-ray pulses produced by high-order harmonics, the cross sections of the two-photon double ionization and above-threshold ionization of He are estimated. The high-intensity soft-x-ray radiation achieved by phase-matched high-order harmonics enables the investigation of these nonlinear optical pr...
82 CitationsSource
#1Yasuo NabekawaH-Index: 27
#2Hiroshi HasegawaH-Index: 18
Last. Katsumi MidorikawaH-Index: 49
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We report on the observation of doubly charged helium ions produced by a nonlinear interaction between a helium atom and photons with a photon energy of 42 eV which are generated with the 27th harmonic of a femtosecond pulse from a Ti:sapphire laser. The number of ions is proportional to the square of the intensity of the 27th harmonic pulse, and thus two-photon double ionization should be dominantly induced as compared with other nonlinear processes accompanying sequential ionization via a sing...
133 CitationsSource
For further development of a variety of applications, one of the most important issues is the improvement of output harmonic energy and conversion efficiency. We review our work on the energy scaling of high-order harmonic generation based on phase-matching using a loosely focused beam. Our harmonic energy scaling method can be universally applied to harmonic generation in the neutral rare gas target. In addition, we demonstrate a new concept for spatial separation between the high-energy pump a...
51 CitationsSource
#1Eiji J. TakahashiH-Index: 7
#2Hiroshi HasegawaH-Index: 18
Last. Katsumi MidorikawaH-Index: 49
view all 4 authors...
We demonstrate a high-throughput and high-damage-threshold beam splitter for high-order harmonics in the soft-x-ray region that uses Si and (or) SiC plates set at Brewster’s angle with respect to the pump wavelength. The beam splitters are guaranteed to have a damage threshold of at least 0.8 TW/cm2 (average power density, 0.25 W/cm2) and an attenuation rate of 10-4–10-5 for a 30-fs pump pulse. The measured reflection efficiency at the 27th harmonic (29.6 nm) was 0.56 for Si and 0.45 for SiC. Th...
76 CitationsSource
Jan 1, 2004 in CLEO (Conference on Lasers and Electro-Optics)
#1Eiji J. TakahashiH-Index: 7
#2Hiroshi HasegawaH-Index: 18
Last. Katsumi MidorikawaH-Index: 49
view all 5 authors...
We demonstrated a high-throughput and high-damage-threshold beam splitter for high-order harmonics using Si, SiC and Mo plates, set at Brewster's angle with respect to the pump wavelength
3 Citations
#1Eiji J. TakahashiH-Index: 7
#2Valer TosaH-Index: 19
Last. Katsumi MidorikawaH-Index: 49
view all 4 authors...
We performed experimental and theoretical analyses of a correlation between pump pulse propagation and harmonic yield in Ar and Xe, in a long static gas cell, at high pumping energies, for loose focusing geometry, using 35-fs pulses from a Ti:sapphire laser. Axial and transverse profiles of the plasma column were measured under several experimental conditions with the aim of characterizing the pulse propagation. From the plasma fluorescence profiles observed, it was found that self-guided propag...
26 CitationsSource
#1Eiji J. TakahashiH-Index: 7
#2Yasuo NabekawaH-Index: 27
Last. Katsumi MidorikawaH-Index: 49
view all 5 authors...
We demonstrated the energy scaling of high-order harmonics using a self-guided beam under the phase-matched condition. By adjusting the argon gas density and pump laser focusing condition, a total output harmonic energy as high as 0.7 \ensuremath{\mu}\mathrm{J}was obtained in the spectral region of 34.8 to 25.8 nm (the corresponding order of the 23rd to 31st harmonic), while the 27th-order harmonic (29.6 nm) energy attained was as high as 0.3 \ensuremath{\mu}\mathrm{J}.
149 CitationsSource
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