We present the most prominent features in two-colour coherent control of high-order harmonic generation using a strongly driven two-level atom model, which are known to generate high harmonics as well as hyper-Raman lines with a plateau and a cut-off. Furthermore, for one laser field case, we find, when the hyper-Raman lines are located at the position of the high harmonics, that the high harmonics are strongly enhanced due to the interference effect between the high harmonics and the hyper-Raman lines. Within these conditions, by combining the laser field with another much weaker laser field, we show plentiful and strong high harmonics in the light spectrum of the driven atomic system.We present the most prominent features in two-colour coherent control of high-order harmonic generation using a strongly driven two-level atom model, which are known to generate high harmonics as well as hyper-Raman lines with a plateau and a cut-off. Furthermore, for one laser field case, we find, when the hyper-Raman lines are located at the position of the high harmonics, that the high harmonics are strongly enhanced due to the interference effect between the high harmonics and the hyper-Raman lines. Within these conditions, by combining the laser field with another much weaker laser field, we show plentiful and strong high harmonics in the light spectrum of the driven atomic system.

Journal of Modern OpticsSep 1, 19997 citations

Frequency distribution of the third harmonic generation in atomic systems

G. Battaglia, G. Vetri

Optics CommunicationsJan 1, 19820 citations

Phase of harmonics from strongly driven two-level atoms

F. I. Gauthey, Christoph H. Keitel, P. L. Knight +1 more

Harmonic generation is studied in an idealized model medium in which the laser field essentially interacts only with a single atomic transition and where ionization can be neglected. Such two-level models are known to generate high harmonics with a plateau and a cutoff. We put forward a quantitative rule for the cutoff frequency in the harmonic spectrum in this model which we relate to the `` ${\mathrm{I}}_{\mathrm{P}}$ + ${3\mathrm{U}}_{\mathrm{P}}$ rule'' in real systems with ionization. We examine the phase properties of the emitted harmonics and show that their coherence and thus phase matching is more favorable in the cutoff regime than in the plateau of the harmonic spectrum. This behavior is known to occur in realistic models of neon, and that this occurs also for the simple idealized two-level model strongly suggests that the sudden change of phase coherence from the cutoff to the plateau regime is as intrinsic a property of nonlinear systems as are the plateau and the cutoff.Harmonic generation is studied in an idealized model medium in which the laser field essentially interacts only with a single atomic transition and where ionization can be neglected. Such two-level models are known to generate high harmonics with a plateau and a cutoff. We put forward a quantitative rule for the cutoff frequency in the harmonic spectrum in this model which we relate to the ``${\mathrm{I}}_{\mathrm{P}}$+${3\mathrm{U}}_{\mathrm{P}}$ rule'' in real systems with ionization. We examine the phase properties of the emitted harmonics and show that their coherence and thus phase matching is more favorable in the cutoff regime than in the plateau of the harmonic spectrum. This behavior is known to occur in realistic models of neon, and that this occurs also for the simple idealized two-level model strongly suggests that the sudden change of phase coherence from the cutoff to the plateau regime is as intrinsic a property of nonlinear systems as are the plateau and the cutoff.

Physical Review AJan 1, 199741 citations

Intracavity second-harmonic generation using an electromagnetically induced transparency

Klaus M. Gheri, C. Saavedra, Daniel F. Walls

We analyze the quantum-fluctuation properties of second-harmonic radiation generated in the high-efficiency conversion process used in a recent experiment by Hakuta, Marmet, and Stoicheff [Phys. Rev. Lett. 66, 596 (1991)]. We extend their work by studying the second-harmonic generation inside an optical cavity. The active medium inside the cavity is modeled by three-level atoms with degenerated upper levels (1s, 2p, and 2s states of atomic hydrogen) interacting with a strong constant electric field. An enhancement of the conversion efficiency and a reduction of the added noise are found as a result of an electromagnetically induced transparency. We show that the scheme is capable of producing light in a squeezed or coherent state close to a minimum-uncertainty state with a large mean amplitude.We analyze the quantum-fluctuation properties of second-harmonic radiation generated in the high-efficiency conversion process used in a recent experiment by Hakuta, Marmet, and Stoicheff [Phys. Rev. Lett. 66, 596 (1991)]. We extend their work by studying the second-harmonic generation inside an optical cavity. The active medium inside the cavity is modeled by three-level atoms with degenerated upper levels (1s, 2p, and 2s states of atomic hydrogen) interacting with a strong constant electric field. An enhancement of the conversion efficiency and a reduction of the added noise are found as a result of an electromagnetically induced transparency. We show that the scheme is capable of producing light in a squeezed or coherent state close to a minimum-uncertainty state with a large mean amplitude.

Physical Review AOct 1, 19935 citations

{\mathrm{I}}_{\mathrm{P}}

{3\mathrm{U}}_{\mathrm{P}}

rule'' in real systems with ionization. We examine the phase properties of the emitted harmonics and show that their coherence and thus phase matching is more favorable in the cutoff regime than in the plateau of the harmonic spectrum. This behavior is known to occur in realistic models of neon, and that this occurs also for the simple idealized two-level model strongly suggests that the sudden change of phase coherence from the cutoff to the plateau regime is as intrinsic a property of nonlinear systems as are the plateau and the cutoff.