Analysis of efficient generation and spatial intensity profiles of high-order harmonic beams produced at high repetition rate

Abstract We report in this paper an experimental study of the spatial profile of harmonic beams (up to the 23rd order) generated in argon with 100 fs titanium-sapphire laser pulses at high repetition rate. In particular, we have investigated high-order harmonic radiation features as a function of the gas target position with respect to the pump laser focus. We have, thus, obtained the experimental conditions that simultaneously optimize generation efficiency and divergence angles of the harmonic beams. As a general trend, both the laser intensity and the harmonic order affect the harmonic beam divergence and spatial profile, depending on whether the harmonics lie in the plateau or in the cutoff region. Finally, we discuss our results in the light of recent theoretical analyses of the process.

[1]  G. Naletto,et al.  Performance of a thinned back-illuminated ion-implanted CCD as detector for a normal incidence EUV spectrograph , 1994 .

[2]  C. Altucci,et al.  Characterization of pulsed gas sources for intense laser field - atom interaction experiments , 1996 .

[3]  R. Haight,et al.  Tunable photoemission with harmonics of subpicosecond lasers , 1994 .

[4]  Haight,et al.  Antibonding state on the Ge(111):As surface: Spectroscopy and dynamics. , 1993, Physical review letters.

[5]  Balcou,et al.  Coherence and resonance effects in high-order harmonic generation. , 1992, Physical review letters.

[6]  K. Eikema,et al.  1ST LASER EXCITATION OF THE HE-4 1(1)S-2(1)P RESONANCE LINE AT 58-NM , 1993 .

[7]  Hutchinson,et al.  Spatial Coherence Measurement of Soft X-Ray Radiation Produced by High Order Harmonic Generation. , 1996, Physical review letters.

[8]  Miyazaki,et al.  High-order harmonic generation in the tunneling regime. , 1995, Physical review. A, Atomic, molecular, and optical physics.

[9]  Balcou,et al.  Phase-matching effects in strong-field harmonic generation. , 1993, Physical review. A, Atomic, molecular, and optical physics.

[10]  C. Wahlström,et al.  Phase-locked high-order harmonic sources , 1997 .

[11]  L'Huillier,et al.  Phase of the atomic polarization in high-order harmonic generation. , 1995, Physical review. A, Atomic, molecular, and optical physics.

[12]  L'Huillier,et al.  High-order harmonic generation in rare gases with an intense short-pulse laser. , 1993, Physical review. A, Atomic, molecular, and optical physics.

[13]  R. B. Kay,et al.  Distortion of the laser beam induced by the electron plasma in harmonic generation experiments , 1993 .

[14]  L'Huillier,et al.  Coherence control of high-order harmonics. , 1995, Physical review letters.

[15]  Peatross,et al.  Intensity-dependent atomic-phase effects in high-order harmonic generation. , 1995, Physical review. A, Atomic, molecular, and optical physics.

[16]  Kenneth C. Kulander,et al.  Intensity-dependent phase-matching effects in harmonic generation , 1995 .