Sub-two-cycle pulses from a Kerr-lens mode-locked Ti:sapphire laser

Morgner, Uwe; Kärtner, Franz X.; Cho, S H; Chen, Y; Haus, H.A.; Fujimoto, James G.; Ippen, Erich P.; Scheuer, V.; Angelow, G.; Tschudi, Τ.

doi:10.1364/ol.24.000411

Cited by 425 publications

(199 citation statements)

References 15 publications

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“…In our experiments, we employ 5 fs linearly polarized optical pulses from a Ti:sapphire mode-locked laser oscillator [13]. The pulses are tightly focused onto the GaAs film, held at room temperature, by means of a high numerical aperture (NA 0:5) reflective microscope objective.…”

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confidence: 99%

Light-Induced Gaps in Semiconductor Band-to-Band Transitions

Haug

Mücke

et al. 2004

Phys. Rev. Lett.

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We observe a triplet around the third harmonic of the semiconductor band gap when exciting 50 -100 nm thin GaAs films with 5 fs pulses at 3 10 12 W=cm 2 . The comparison with solutions of the semiconductor Bloch equations allows us to interpret the observed peak structure as being due to a twoband Mollow triplet. This triplet in the optical spectrum is a result of light-induced gaps in the band structure, which arise from coherent band mixing. The theory is formulated for full tight-binding bands and uses no rotating-wave approximation. DOI: 10.1103/PhysRevLett.92.217403 PACS numbers: 78.20.Bh, 42.50.Md, 42.65.Re, 78.47.+p When an intense light field at frequency ! 0 excites band-to-band transitions in a semiconductor, additional energy gaps can evolve within the original bands [ Fig. 1(b)]. These so-called light-induced gaps [1][2][3][4][5] are the analog of the induced doublets, split by the Rabi frequency R , in a resonantly excited two-level system [ Fig. 1(a)]. Here, two out of the four possible optical transitions are energetically degenerate. Hence, the optical spectrum consists of three peaks -the famous Mollow triplet for atoms [6,7] or excitons [8,9]. In the semiconductor band case, the light-induced gap in, e.g., the conduction band arises because the original conduction band and the one-photon sideband of the valence band lead to an avoided crossing. The corresponding Hopfield coefficients [1] determine the amount of conduction band admixture. It is crucial to note that this admixture can be finite even far away from the fictitious crossing point. This statement becomes particularly important for Rabi energies h R approaching the photon energy h! 0 , while it can be neglected for small Rabi energies. The latter case is tacitly assumed in previous graphical representations of calculated light-induced gaps. Importantly, as a result of this finite admixture, optical transitions between the induced bands are possible throughout an appreciable fraction of momentum space. Consequently, the transitions acquire considerable spectral weight. Again, two out of the four sets of possible optical transitions are energetically degenerate and a triplet results, which we will refer to as the two-band Mollow triplet in what follows.Light-induced gaps in semiconductor bands have not unambiguously been observed yet. In order to observe the splitting, it clearly has to be larger than the damping. As typical electron dephasing times under relevant conditions are on the order of 10 fs or less, the Rabi oscillation period has to be shorter than this value. This brings one close to Rabi frequencies approaching the frequency of light -a regime which has previously been referred to as carrier-wave Rabi flopping [10]. In this regime, a splitting in the third-harmonic spectra has been observed [11]. However, as the measurements have been compared only with calculations on the basis of two-level systems [11], skepticism has been expressed whether this interpretation was correct indeed. Furthermore, later theoretical work [12...

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confidence: 99%

Light-Induced Gaps in Semiconductor Band-to-Band Transitions

Haug

Mücke

et al. 2004

Phys. Rev. Lett.

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“…[In contrast to this, the Schwinger acceleration is (4) at which an electron gains energy by moc 2 over the Compton length AC =H/mQC, and the pair creation becomes prevalent.] A large flux of photons bombarding an electron causes such high acceleration through collisions between photons and electrons (Compton collisions).…”

Section: High-field Science In Extreme Fieldsmentioning

confidence: 99%

“…A number of laboratories are presently equipped with CPA ultrashort-pulsed terawatt lasers such as Laboratoire Optique Applique in France, University of Lund in Sweden, Max-Planck Institute in Garching, Jena University, and the Japan Atomic Energy Research Institute in Kansai. The CPA-enabled short-pulse generation has advanced to the single-cycle regime [4]. The peak power in the 1990s reached 100 TW, demonstrated at JAERI Kansai.…”

Section: Introductionmentioning

confidence: 99%

Superstrong field science

Tajima¹,

Mourou²

2002

AIP Conference Proceedings

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Abstract. Over the past fifteen years we have seen a surge in our ability to produce high intensities, five to six orders of magnitude higher than was possible before. At these intensities, particles, electrons and protons, acquire kinetic energy in the mega-electron-volt range through interaction with intense laser fields. This opens a new age for the laser, the age of nonlinear relativistic optics coupling even with nuclear physics. We suggest a path to reach an extremely high-intensity level 10 26~28 W/cm 2 in the coming decade, much beyond the current and near future intensity regime 10 23 W/cm 2 , taking advantage of the megajoule laser facilities. Such a laser at extreme high intensity could accelerate particles to frontiers of high energy, tera-electron-volt and peta-electronvolt, and would become a tool of fundamental physics encompassing particle physics, gravitational physics, nonlinear field theory, ultrahigh-pressure physics, astrophysics, and cosmology. Such a laser intensity may also be very beneficial to an alternative, more direct approach of fast ignition in laser fusion. We suggest a new possibility to explore this.

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“…Alternatively, a mixture of prisms and mirrors can be used to generate pulses as short as 5 fs. 26 At the time of writing, the use of mirrors with well-defined chirp characteristics is complicated by the demand for extreme tolerances in the manufacturing process. Many schemes have been proposed for selfstarting oscillators, perhaps the best of which is the use of a broadband semiconductor saturable-absorber mirror in the cavity.…”

Section: Oscillatorsmentioning

confidence: 99%

Ultrafast Laser Technology and Spectroscopy

Reid

Wynne

2000

Encyclopedia of Analytical Chemistry

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Ultrafast laser technology and spectroscopy involves the use of femtosecond (10 −15 s) laser and other (particle) sources to study the properties of matter. The extremely short pulse duration allows one to create, detect and study very short‐lived transient chemical reaction intermediates and transition states. Ultrafast lasers can also be used to produce laser pulses with enormous peak powers and power densities. This leads to applications such as laser machining and ablation, generation of electromagnetic radiation at unusual wavelengths (such as millimeter waves and X‐rays), and multiphoton imaging. The difficulty in applying femtosecond laser pulses is that the broad frequency spectrum can lead to temporal broadening of the pulse on propagation through the experimental set‐up. In this article, we describe the generation and amplification of femtosecond laser pulses and the various techniques that have been developed to characterize and manipulate the pulses.

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Sub-two-cycle pulses from a Kerr-lens mode-locked Ti:sapphire laser

Cited by 425 publications

References 15 publications

Light-Induced Gaps in Semiconductor Band-to-Band Transitions

Light-Induced Gaps in Semiconductor Band-to-Band Transitions

Superstrong field science

Ultrafast Laser Technology and Spectroscopy

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