A. B. Kim, M. Yu. Ryabikin, and A. M. Sergeyev, “From femtosecond to attosecond pulses,”Usp. Fiz. Nauk 169, 58–66 (1999) [ Phys. Usp. 42, 56–61 (1999)].

V. D. Taranukhin and N. Yu. Shubin, “High-order harmonic generation by atoms with strong bichromatic fields,” Quantum Electron. 29, 638–643 (1999).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

M. Schnürer, Z. Cheng, M. Hentschel, G. Tempea, P. Kálmán, T. Brabec, and F. Krausz, “Absorption-limited generation of coherent ultrashort soft-x-ray pulses,” Phys. Rev. Lett. 83, 722–725 (1999).

A. Scrinzi, M. Geissler, and T. Brabec, “Ionization above the Coulomb barrier,” Phys. Rev. Lett. 83, 706–709 (1998).

R. V. Kulyagin and V. D. Taranukhin, “Features of high-harmonic generation by atoms at superintense and ultrashort laser pumping,” Laser Phys. 7, 623–626 (1997).

A. Lohr, W. Becker, and M. Kleber, “High-harmonic generation affected by a static electric field,” Laser Phys. 7, 615–622 (1997).

J. Peatross, S. Voronov, and I. Prokopovich, “Selective zoning of high harmonic emission using counter-propagating light,” Opt. Express 1, 114–125 (1997), http://www.opticsexpress.org.

Z. Chang, A. Rundquist, H.-W. Wang, M. M. Murnane, and H. C. Kapteyn, “Generation of coherent soft x rays at 2.7 nm using high harmonics,” Phys. Rev. Lett. 79, 2967–2970 (1997).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization: electron rescattering and generation of short-wavelength radiation,” Laser Phys. 6, 79–83 (1996).

R. V. Kulyagin and V. D. Taranukhin, “Generation of x-ray radiation by atoms in an ultra-high intensity laser field,” Quantum Electron. 26, 866–870 (1996).

C. H. Keitel and P. L. Knight, “Monte Carlo classical simulations of ionization and harmonic generation in the relativistic domain,” Phys. Rev. A 51, 1420–1430 (1995).

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization of atoms and generation of short-wavelength radiation,” in Laser Optics ’95 and ICONO ’95: Superintense Laser Fields, A. A. Andreev and V. M. Gordienko, eds., Proc. SPIE 2770, 46–52 (1995).

N. H. Burnett, C. Kan, and P. B. Corkum, “Ellipticity and polarization effects in harmonic generation in ionizing neon,” Phys. Rev. A 51, R3418–R3421 (1995).

D. P. Crawford and H. R. Reiss, “Stabilization in relativistic photoionization with circularly polarized light,” Phys. Rev. A 50, 1844–1850 (1994).

K. Kondo, T. Tamida, Y. Nabekawa, and S. Watanabe, “High-order harmonic generation and ionization using ultrashort KrF and Ti:sapphire lasers,” Phys. Rev. A 49, 3881–3889 (1994).

P. B. Corkum, N. H. Burnett, and M. Yu. Ivanov, “Subfemtosecond pulses,” Opt. Lett. 19, 1870–1872 (1994).

M. Lewenstein, Ph. Balcou, M. Yu. Ivanov, A. L’Huillier, and P. B. Corkum, “Theory of high-harmonic generation by low-frequency laser fields,” Phys. Rev. A 49, 2117–2132 (1994).

P. B. Corkum, “Plasma perspective on strong-field multiphoton ionization,” Phys. Rev. Lett. 71, 1994–1997 (1993).

Sh. Kubodera, Yu. Nagata, Ya. Akiyama, K. Midorikawa, M. Obara, H. Tashiro, and K. Toyoda, “High order harmonics in laser-produced ions,” Phys. Rev. A 48, 4576–4582 (1993).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

K. C. Budil, P. Salieres, A. L’Huillier, T. Ditmire, and M. D. Perry, “Influence of ellipticity on harmonic generation,” Phys. Rev. A 48, R3437–R3440 (1993).

J. L. Krause, K. J. Schafer, and K. C. Kulander, “High-order harmonic generation from atoms and ions in the high intensity regime,” Phys. Rev. Lett. 68, 3535–3558 (1992).

N. Sarukura, K. Hata, T. Adachi, R. Nodomi, M. Watanabe, and S. Watanabe, “Coherent soft x-ray generation by the harmonics of an ultra-high power Kr–F laser,” Phys. Rev. A 43, 1669–1672 (1991).

V. M. Vainberg, V. D. Mur, V. S. Popov, and A. V. Sergeev, “Hydrogen atom in a strong static field,” Sov. Phys. JETP 66, 258–270 (1987).

M. Lax, W. H. Louisell, and W. B. Knight, “From Maxwell to paraxial wave optics,” Phys. Rev. A 11, 1365–1370 (1975).

A. M. Perelomov, V. S. Popov, and M. V. Terent’ev, “Ionization of atoms with electric AC fields,” Sov. Phys. JETP 24, 207–217 (1967).

L. V. Keldysh, “Ionization in the field of a strong electromagnetic wave,” Sov. Phys. JETP 20, 1307–1318 (1965).

N. Sarukura, K. Hata, T. Adachi, R. Nodomi, M. Watanabe, and S. Watanabe, “Coherent soft x-ray generation by the harmonics of an ultra-high power Kr–F laser,” Phys. Rev. A 43, 1669–1672 (1991).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

Sh. Kubodera, Yu. Nagata, Ya. Akiyama, K. Midorikawa, M. Obara, H. Tashiro, and K. Toyoda, “High order harmonics in laser-produced ions,” Phys. Rev. A 48, 4576–4582 (1993).

M. Lewenstein, Ph. Balcou, M. Yu. Ivanov, A. L’Huillier, and P. B. Corkum, “Theory of high-harmonic generation by low-frequency laser fields,” Phys. Rev. A 49, 2117–2132 (1994).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

A. Lohr, W. Becker, and M. Kleber, “High-harmonic generation affected by a static electric field,” Laser Phys. 7, 615–622 (1997).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

M. Schnürer, Z. Cheng, M. Hentschel, G. Tempea, P. Kálmán, T. Brabec, and F. Krausz, “Absorption-limited generation of coherent ultrashort soft-x-ray pulses,” Phys. Rev. Lett. 83, 722–725 (1999).

A. Scrinzi, M. Geissler, and T. Brabec, “Ionization above the Coulomb barrier,” Phys. Rev. Lett. 83, 706–709 (1998).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

K. C. Budil, P. Salieres, A. L’Huillier, T. Ditmire, and M. D. Perry, “Influence of ellipticity on harmonic generation,” Phys. Rev. A 48, R3437–R3440 (1993).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

N. H. Burnett, C. Kan, and P. B. Corkum, “Ellipticity and polarization effects in harmonic generation in ionizing neon,” Phys. Rev. A 51, R3418–R3421 (1995).

P. B. Corkum, N. H. Burnett, and M. Yu. Ivanov, “Subfemtosecond pulses,” Opt. Lett. 19, 1870–1872 (1994).

Z. Chang, A. Rundquist, H.-W. Wang, M. M. Murnane, and H. C. Kapteyn, “Generation of coherent soft x rays at 2.7 nm using high harmonics,” Phys. Rev. Lett. 79, 2967–2970 (1997).

M. Schnürer, Z. Cheng, M. Hentschel, G. Tempea, P. Kálmán, T. Brabec, and F. Krausz, “Absorption-limited generation of coherent ultrashort soft-x-ray pulses,” Phys. Rev. Lett. 83, 722–725 (1999).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

N. H. Burnett, C. Kan, and P. B. Corkum, “Ellipticity and polarization effects in harmonic generation in ionizing neon,” Phys. Rev. A 51, R3418–R3421 (1995).

M. Lewenstein, Ph. Balcou, M. Yu. Ivanov, A. L’Huillier, and P. B. Corkum, “Theory of high-harmonic generation by low-frequency laser fields,” Phys. Rev. A 49, 2117–2132 (1994).

P. B. Corkum, N. H. Burnett, and M. Yu. Ivanov, “Subfemtosecond pulses,” Opt. Lett. 19, 1870–1872 (1994).

P. B. Corkum, “Plasma perspective on strong-field multiphoton ionization,” Phys. Rev. Lett. 71, 1994–1997 (1993).

D. P. Crawford and H. R. Reiss, “Stabilization in relativistic photoionization with circularly polarized light,” Phys. Rev. A 50, 1844–1850 (1994).

K. C. Budil, P. Salieres, A. L’Huillier, T. Ditmire, and M. D. Perry, “Influence of ellipticity on harmonic generation,” Phys. Rev. A 48, R3437–R3440 (1993).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

A. Scrinzi, M. Geissler, and T. Brabec, “Ionization above the Coulomb barrier,” Phys. Rev. Lett. 83, 706–709 (1998).

N. Sarukura, K. Hata, T. Adachi, R. Nodomi, M. Watanabe, and S. Watanabe, “Coherent soft x-ray generation by the harmonics of an ultra-high power Kr–F laser,” Phys. Rev. A 43, 1669–1672 (1991).

M. Schnürer, Z. Cheng, M. Hentschel, G. Tempea, P. Kálmán, T. Brabec, and F. Krausz, “Absorption-limited generation of coherent ultrashort soft-x-ray pulses,” Phys. Rev. Lett. 83, 722–725 (1999).

M. Lewenstein, Ph. Balcou, M. Yu. Ivanov, A. L’Huillier, and P. B. Corkum, “Theory of high-harmonic generation by low-frequency laser fields,” Phys. Rev. A 49, 2117–2132 (1994).

P. B. Corkum, N. H. Burnett, and M. Yu. Ivanov, “Subfemtosecond pulses,” Opt. Lett. 19, 1870–1872 (1994).

M. Schnürer, Z. Cheng, M. Hentschel, G. Tempea, P. Kálmán, T. Brabec, and F. Krausz, “Absorption-limited generation of coherent ultrashort soft-x-ray pulses,” Phys. Rev. Lett. 83, 722–725 (1999).

N. H. Burnett, C. Kan, and P. B. Corkum, “Ellipticity and polarization effects in harmonic generation in ionizing neon,” Phys. Rev. A 51, R3418–R3421 (1995).

Z. Chang, A. Rundquist, H.-W. Wang, M. M. Murnane, and H. C. Kapteyn, “Generation of coherent soft x rays at 2.7 nm using high harmonics,” Phys. Rev. Lett. 79, 2967–2970 (1997).

C. H. Keitel and P. L. Knight, “Monte Carlo classical simulations of ionization and harmonic generation in the relativistic domain,” Phys. Rev. A 51, 1420–1430 (1995).

L. V. Keldysh, “Ionization in the field of a strong electromagnetic wave,” Sov. Phys. JETP 20, 1307–1318 (1965).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

A. B. Kim, M. Yu. Ryabikin, and A. M. Sergeyev, “From femtosecond to attosecond pulses,”Usp. Fiz. Nauk 169, 58–66 (1999) [ Phys. Usp. 42, 56–61 (1999)].

A. Lohr, W. Becker, and M. Kleber, “High-harmonic generation affected by a static electric field,” Laser Phys. 7, 615–622 (1997).

C. H. Keitel and P. L. Knight, “Monte Carlo classical simulations of ionization and harmonic generation in the relativistic domain,” Phys. Rev. A 51, 1420–1430 (1995).

M. Lax, W. H. Louisell, and W. B. Knight, “From Maxwell to paraxial wave optics,” Phys. Rev. A 11, 1365–1370 (1975).

K. Kondo, T. Tamida, Y. Nabekawa, and S. Watanabe, “High-order harmonic generation and ionization using ultrashort KrF and Ti:sapphire lasers,” Phys. Rev. A 49, 3881–3889 (1994).

J. L. Krause, K. J. Schafer, and K. C. Kulander, “High-order harmonic generation from atoms and ions in the high intensity regime,” Phys. Rev. Lett. 68, 3535–3558 (1992).

M. Schnürer, Z. Cheng, M. Hentschel, G. Tempea, P. Kálmán, T. Brabec, and F. Krausz, “Absorption-limited generation of coherent ultrashort soft-x-ray pulses,” Phys. Rev. Lett. 83, 722–725 (1999).

Sh. Kubodera, Yu. Nagata, Ya. Akiyama, K. Midorikawa, M. Obara, H. Tashiro, and K. Toyoda, “High order harmonics in laser-produced ions,” Phys. Rev. A 48, 4576–4582 (1993).

J. L. Krause, K. J. Schafer, and K. C. Kulander, “High-order harmonic generation from atoms and ions in the high intensity regime,” Phys. Rev. Lett. 68, 3535–3558 (1992).

R. V. Kulyagin and V. D. Taranukhin, “Features of high-harmonic generation by atoms at superintense and ultrashort laser pumping,” Laser Phys. 7, 623–626 (1997).

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization: electron rescattering and generation of short-wavelength radiation,” Laser Phys. 6, 79–83 (1996).

R. V. Kulyagin and V. D. Taranukhin, “Generation of x-ray radiation by atoms in an ultra-high intensity laser field,” Quantum Electron. 26, 866–870 (1996).

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization of atoms and generation of short-wavelength radiation,” in Laser Optics ’95 and ICONO ’95: Superintense Laser Fields, A. A. Andreev and V. M. Gordienko, eds., Proc. SPIE 2770, 46–52 (1995).

M. Lewenstein, Ph. Balcou, M. Yu. Ivanov, A. L’Huillier, and P. B. Corkum, “Theory of high-harmonic generation by low-frequency laser fields,” Phys. Rev. A 49, 2117–2132 (1994).

K. C. Budil, P. Salieres, A. L’Huillier, T. Ditmire, and M. D. Perry, “Influence of ellipticity on harmonic generation,” Phys. Rev. A 48, R3437–R3440 (1993).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

M. Lax, W. H. Louisell, and W. B. Knight, “From Maxwell to paraxial wave optics,” Phys. Rev. A 11, 1365–1370 (1975).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

M. Lewenstein, Ph. Balcou, M. Yu. Ivanov, A. L’Huillier, and P. B. Corkum, “Theory of high-harmonic generation by low-frequency laser fields,” Phys. Rev. A 49, 2117–2132 (1994).

A. Lohr, W. Becker, and M. Kleber, “High-harmonic generation affected by a static electric field,” Laser Phys. 7, 615–622 (1997).

M. Lax, W. H. Louisell, and W. B. Knight, “From Maxwell to paraxial wave optics,” Phys. Rev. A 11, 1365–1370 (1975).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

Sh. Kubodera, Yu. Nagata, Ya. Akiyama, K. Midorikawa, M. Obara, H. Tashiro, and K. Toyoda, “High order harmonics in laser-produced ions,” Phys. Rev. A 48, 4576–4582 (1993).

V. M. Vainberg, V. D. Mur, V. S. Popov, and A. V. Sergeev, “Hydrogen atom in a strong static field,” Sov. Phys. JETP 66, 258–270 (1987).

Z. Chang, A. Rundquist, H.-W. Wang, M. M. Murnane, and H. C. Kapteyn, “Generation of coherent soft x rays at 2.7 nm using high harmonics,” Phys. Rev. Lett. 79, 2967–2970 (1997).

K. Kondo, T. Tamida, Y. Nabekawa, and S. Watanabe, “High-order harmonic generation and ionization using ultrashort KrF and Ti:sapphire lasers,” Phys. Rev. A 49, 3881–3889 (1994).

Sh. Kubodera, Yu. Nagata, Ya. Akiyama, K. Midorikawa, M. Obara, H. Tashiro, and K. Toyoda, “High order harmonics in laser-produced ions,” Phys. Rev. A 48, 4576–4582 (1993).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

N. Sarukura, K. Hata, T. Adachi, R. Nodomi, M. Watanabe, and S. Watanabe, “Coherent soft x-ray generation by the harmonics of an ultra-high power Kr–F laser,” Phys. Rev. A 43, 1669–1672 (1991).

Sh. Kubodera, Yu. Nagata, Ya. Akiyama, K. Midorikawa, M. Obara, H. Tashiro, and K. Toyoda, “High order harmonics in laser-produced ions,” Phys. Rev. A 48, 4576–4582 (1993).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

A. M. Perelomov, V. S. Popov, and M. V. Terent’ev, “Ionization of atoms with electric AC fields,” Sov. Phys. JETP 24, 207–217 (1967).

K. C. Budil, P. Salieres, A. L’Huillier, T. Ditmire, and M. D. Perry, “Influence of ellipticity on harmonic generation,” Phys. Rev. A 48, R3437–R3440 (1993).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

V. M. Vainberg, V. D. Mur, V. S. Popov, and A. V. Sergeev, “Hydrogen atom in a strong static field,” Sov. Phys. JETP 66, 258–270 (1987).

A. M. Perelomov, V. S. Popov, and M. V. Terent’ev, “Ionization of atoms with electric AC fields,” Sov. Phys. JETP 24, 207–217 (1967).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

D. P. Crawford and H. R. Reiss, “Stabilization in relativistic photoionization with circularly polarized light,” Phys. Rev. A 50, 1844–1850 (1994).

Z. Chang, A. Rundquist, H.-W. Wang, M. M. Murnane, and H. C. Kapteyn, “Generation of coherent soft x rays at 2.7 nm using high harmonics,” Phys. Rev. Lett. 79, 2967–2970 (1997).

A. B. Kim, M. Yu. Ryabikin, and A. M. Sergeyev, “From femtosecond to attosecond pulses,”Usp. Fiz. Nauk 169, 58–66 (1999) [ Phys. Usp. 42, 56–61 (1999)].

K. C. Budil, P. Salieres, A. L’Huillier, T. Ditmire, and M. D. Perry, “Influence of ellipticity on harmonic generation,” Phys. Rev. A 48, R3437–R3440 (1993).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

N. Sarukura, K. Hata, T. Adachi, R. Nodomi, M. Watanabe, and S. Watanabe, “Coherent soft x-ray generation by the harmonics of an ultra-high power Kr–F laser,” Phys. Rev. A 43, 1669–1672 (1991).

J. L. Krause, K. J. Schafer, and K. C. Kulander, “High-order harmonic generation from atoms and ions in the high intensity regime,” Phys. Rev. Lett. 68, 3535–3558 (1992).

M. Schnürer, Z. Cheng, M. Hentschel, G. Tempea, P. Kálmán, T. Brabec, and F. Krausz, “Absorption-limited generation of coherent ultrashort soft-x-ray pulses,” Phys. Rev. Lett. 83, 722–725 (1999).

A. Scrinzi, M. Geissler, and T. Brabec, “Ionization above the Coulomb barrier,” Phys. Rev. Lett. 83, 706–709 (1998).

V. M. Vainberg, V. D. Mur, V. S. Popov, and A. V. Sergeev, “Hydrogen atom in a strong static field,” Sov. Phys. JETP 66, 258–270 (1987).

A. B. Kim, M. Yu. Ryabikin, and A. M. Sergeyev, “From femtosecond to attosecond pulses,”Usp. Fiz. Nauk 169, 58–66 (1999) [ Phys. Usp. 42, 56–61 (1999)].

V. D. Taranukhin and N. Yu. Shubin, “High-order harmonic generation by atoms with strong high-frequency and low-frequency pumping,” J. Opt. Soc. Am. B 17, 1509–1516 (2000).

V. D. Taranukhin and N. Yu. Shubin, “High-order harmonic generation by atoms with strong bichromatic fields,” Quantum Electron. 29, 638–643 (1999).

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization: electron rescattering and generation of short-wavelength radiation,” Laser Phys. 6, 79–83 (1996).

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization of atoms and generation of short-wavelength radiation,” in Laser Optics ’95 and ICONO ’95: Superintense Laser Fields, A. A. Andreev and V. M. Gordienko, eds., Proc. SPIE 2770, 46–52 (1995).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

K. Kondo, T. Tamida, Y. Nabekawa, and S. Watanabe, “High-order harmonic generation and ionization using ultrashort KrF and Ti:sapphire lasers,” Phys. Rev. A 49, 3881–3889 (1994).

V. D. Taranukhin and N. Yu. Shubin, “High-order harmonic generation by atoms with strong high-frequency and low-frequency pumping,” J. Opt. Soc. Am. B 17, 1509–1516 (2000).

V. D. Taranukhin, “Relativistic high-order harmonic generation,” Laser Phys. 10, 330–336 (2000).

V. D. Taranukhin and N. Yu. Shubin, “High-order harmonic generation by atoms with strong bichromatic fields,” Quantum Electron. 29, 638–643 (1999).

R. V. Kulyagin and V. D. Taranukhin, “Features of high-harmonic generation by atoms at superintense and ultrashort laser pumping,” Laser Phys. 7, 623–626 (1997).

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization: electron rescattering and generation of short-wavelength radiation,” Laser Phys. 6, 79–83 (1996).

R. V. Kulyagin and V. D. Taranukhin, “Generation of x-ray radiation by atoms in an ultra-high intensity laser field,” Quantum Electron. 26, 866–870 (1996).

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization of atoms and generation of short-wavelength radiation,” in Laser Optics ’95 and ICONO ’95: Superintense Laser Fields, A. A. Andreev and V. M. Gordienko, eds., Proc. SPIE 2770, 46–52 (1995).

Sh. Kubodera, Yu. Nagata, Ya. Akiyama, K. Midorikawa, M. Obara, H. Tashiro, and K. Toyoda, “High order harmonics in laser-produced ions,” Phys. Rev. A 48, 4576–4582 (1993).

M. Schnürer, Z. Cheng, M. Hentschel, G. Tempea, P. Kálmán, T. Brabec, and F. Krausz, “Absorption-limited generation of coherent ultrashort soft-x-ray pulses,” Phys. Rev. Lett. 83, 722–725 (1999).

A. M. Perelomov, V. S. Popov, and M. V. Terent’ev, “Ionization of atoms with electric AC fields,” Sov. Phys. JETP 24, 207–217 (1967).

Sh. Kubodera, Yu. Nagata, Ya. Akiyama, K. Midorikawa, M. Obara, H. Tashiro, and K. Toyoda, “High order harmonics in laser-produced ions,” Phys. Rev. A 48, 4576–4582 (1993).

V. M. Vainberg, V. D. Mur, V. S. Popov, and A. V. Sergeev, “Hydrogen atom in a strong static field,” Sov. Phys. JETP 66, 258–270 (1987).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

Z. Chang, A. Rundquist, H.-W. Wang, M. M. Murnane, and H. C. Kapteyn, “Generation of coherent soft x rays at 2.7 nm using high harmonics,” Phys. Rev. Lett. 79, 2967–2970 (1997).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

N. Sarukura, K. Hata, T. Adachi, R. Nodomi, M. Watanabe, and S. Watanabe, “Coherent soft x-ray generation by the harmonics of an ultra-high power Kr–F laser,” Phys. Rev. A 43, 1669–1672 (1991).

K. Kondo, T. Tamida, Y. Nabekawa, and S. Watanabe, “High-order harmonic generation and ionization using ultrashort KrF and Ti:sapphire lasers,” Phys. Rev. A 49, 3881–3889 (1994).

N. Sarukura, K. Hata, T. Adachi, R. Nodomi, M. Watanabe, and S. Watanabe, “Coherent soft x-ray generation by the harmonics of an ultra-high power Kr–F laser,” Phys. Rev. A 43, 1669–1672 (1991).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

A. Lohr, W. Becker, and M. Kleber, “High-harmonic generation affected by a static electric field,” Laser Phys. 7, 615–622 (1997).

R. V. Kulyagin and V. D. Taranukhin, “Features of high-harmonic generation by atoms at superintense and ultrashort laser pumping,” Laser Phys. 7, 623–626 (1997).

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization: electron rescattering and generation of short-wavelength radiation,” Laser Phys. 6, 79–83 (1996).

V. D. Taranukhin, “Relativistic high-order harmonic generation,” Laser Phys. 10, 330–336 (2000).

D. P. Crawford and H. R. Reiss, “Stabilization in relativistic photoionization with circularly polarized light,” Phys. Rev. A 50, 1844–1850 (1994).

M. Lax, W. H. Louisell, and W. B. Knight, “From Maxwell to paraxial wave optics,” Phys. Rev. A 11, 1365–1370 (1975).

K. C. Budil, P. Salieres, A. L’Huillier, T. Ditmire, and M. D. Perry, “Influence of ellipticity on harmonic generation,” Phys. Rev. A 48, R3437–R3440 (1993).

N. H. Burnett, C. Kan, and P. B. Corkum, “Ellipticity and polarization effects in harmonic generation in ionizing neon,” Phys. Rev. A 51, R3418–R3421 (1995).

M. Lewenstein, Ph. Balcou, M. Yu. Ivanov, A. L’Huillier, and P. B. Corkum, “Theory of high-harmonic generation by low-frequency laser fields,” Phys. Rev. A 49, 2117–2132 (1994).

N. Sarukura, K. Hata, T. Adachi, R. Nodomi, M. Watanabe, and S. Watanabe, “Coherent soft x-ray generation by the harmonics of an ultra-high power Kr–F laser,” Phys. Rev. A 43, 1669–1672 (1991).

Sh. Kubodera, Yu. Nagata, Ya. Akiyama, K. Midorikawa, M. Obara, H. Tashiro, and K. Toyoda, “High order harmonics in laser-produced ions,” Phys. Rev. A 48, 4576–4582 (1993).

C. G. Wahlstrom, J. Larsson, A. Persson, T. Starczewski, S. Svanberg, P. Salieres, Ph. Balcou, and A. L’Huillier, “High-order harmonic generation in rare gases with an intense short-pulse laser,” Phys. Rev. A 48, 4709–4720 (1993).

K. Kondo, T. Tamida, Y. Nabekawa, and S. Watanabe, “High-order harmonic generation and ionization using ultrashort KrF and Ti:sapphire lasers,” Phys. Rev. A 49, 3881–3889 (1994).

S. G. Preston, A. Sanpera, M. Zepf, W. J. Blyth, C. G. Smith, J. S. Wark, M. H. Key, K. Burnett, M. Nakai, D. Neely, and A. A. Offenberger, “High-order harmonics of a 248.6 nm KrF laser from helium and neon ions,” Phys. Rev. A 53, R31–R34 (1996).

C. H. Keitel and P. L. Knight, “Monte Carlo classical simulations of ionization and harmonic generation in the relativistic domain,” Phys. Rev. A 51, 1420–1430 (1995).

E. Constant, D. Garzella, P. Breger, E. Mével, Ch. Dorrer, C. Le Blanc, F. Salin, and P. Agostini, “Optimizing high harmonic generation in absorbing gases: model and experiment,” Phys. Rev. Lett. 82, 1668–1671 (1999).

Z. Chang, A. Rundquist, H.-W. Wang, M. M. Murnane, and H. C. Kapteyn, “Generation of coherent soft x rays at 2.7 nm using high harmonics,” Phys. Rev. Lett. 79, 2967–2970 (1997).

M. Schnürer, Z. Cheng, M. Hentschel, G. Tempea, P. Kálmán, T. Brabec, and F. Krausz, “Absorption-limited generation of coherent ultrashort soft-x-ray pulses,” Phys. Rev. Lett. 83, 722–725 (1999).

P. B. Corkum, “Plasma perspective on strong-field multiphoton ionization,” Phys. Rev. Lett. 71, 1994–1997 (1993).

J. L. Krause, K. J. Schafer, and K. C. Kulander, “High-order harmonic generation from atoms and ions in the high intensity regime,” Phys. Rev. Lett. 68, 3535–3558 (1992).

A. Scrinzi, M. Geissler, and T. Brabec, “Ionization above the Coulomb barrier,” Phys. Rev. Lett. 83, 706–709 (1998).

A. B. Kim, M. Yu. Ryabikin, and A. M. Sergeyev, “From femtosecond to attosecond pulses,”Usp. Fiz. Nauk 169, 58–66 (1999) [ Phys. Usp. 42, 56–61 (1999)].

R. V. Kulyagin, N. Yu. Shubin, and V. D. Taranukhin, “Tunnel above-threshold ionization of atoms and generation of short-wavelength radiation,” in Laser Optics ’95 and ICONO ’95: Superintense Laser Fields, A. A. Andreev and V. M. Gordienko, eds., Proc. SPIE 2770, 46–52 (1995).

V. D. Taranukhin and N. Yu. Shubin, “High-order harmonic generation by atoms with strong bichromatic fields,” Quantum Electron. 29, 638–643 (1999).

R. V. Kulyagin and V. D. Taranukhin, “Generation of x-ray radiation by atoms in an ultra-high intensity laser field,” Quantum Electron. 26, 866–870 (1996).

A. M. Perelomov, V. S. Popov, and M. V. Terent’ev, “Ionization of atoms with electric AC fields,” Sov. Phys. JETP 24, 207–217 (1967).

V. M. Vainberg, V. D. Mur, V. S. Popov, and A. V. Sergeev, “Hydrogen atom in a strong static field,” Sov. Phys. JETP 66, 258–270 (1987).

L. V. Keldysh, “Ionization in the field of a strong electromagnetic wave,” Sov. Phys. JETP 20, 1307–1318 (1965).

V. D. Taranukhin, “Generation of coherent x-ray radiation by atoms in superstrong laser fields: fundamental restrictions, optimizations and ultimate possibilities,” in Technical Digest, XVI International Conference on Coherent and Nonlinear Optics (URSS Publishers, Moscow, 1998), p. 118.

V. D. Taranukhin and N. Yu. Shubin, “Coherent x-ray generation by ions with standing wave pump radiation of relativistic intensity,” presented at the 8th Conference on Applications of High Field and Short Wavelength Sources, Potsdam, Germany (June 27–30, 1999).

V. D. Taranukhin and N. Yu. Shubin, “High-order harmonic generation by multielectron atoms with laser standing wave of relativistic intensity,” in Book of Abstracts, 8th Annual International Laser Physics Workshop (Research Institute for Solid State Physics and Optics, Budapest, Hungary, 1999), pp. 103–104.