Article

Nonperturbative Interband Response of a Bulk InSb Semiconductor Driven Off Resonantly by Terahertz Electromagnetic Few-Cycle Pulses

Department of Physics and Center for Applied Photonics, University of Konstanz, Universitätsstr. 10, 78457 Konstanz, Germany.
Physical Review Letters (Impact Factor: 7.51). 10/2012; 109(14):147403. DOI: 10.1103/PhysRevLett.109.147403
Source: PubMed

ABSTRACT

Intense multiterahertz pulses are used to study the coherent nonlinear response of bulk InSb by means of field-resolved four-wave mixing spectroscopy. At amplitudes above 5  MV/cm the signals show a clear temporal substructure which is unexpected in perturbative nonlinear optics. Simulations based on a model of a two-level quantum system demonstrate that in spite of the strongly off-resonant character of the excitation the high-field few-cycle pulses drive the interband resonances into a nonperturbative regime of Rabi flopping. The rotating wave approximation breaks down in this case and the system reaches a complete population inversion.

  • Source
    • "However, such an approach does not enhance spectral bandwidth and imposes technical limitations when extended to midand far-infrared regions. Nevertheless, intense pulses in these spectral regions are especially appealing as they enable control of low-energy fundamental excitations in condensed matter [5] [6], and observation of previously elusive transport phenomena in high electric fields [7] [8] [9]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate sub-cycle manipulation of mid-infrared optical waveforms in the time domain. This goal is accomplished via efficient reflection at a semiconductor surface induced by femtosecond interband excitation. The ultrafast response of this process allows slicing of high-field multi-terahertz transients down to the single optical cycle. Ultrabroadband and phase-stable transients with peak amplitudes beyond 10 MV cm−1 are obtained, paving the way for efficient coherent control of light–matter interaction in the non-perturbative regime. The microscopic analysis of electron–hole plasma generation in germanium reveals a decisive role of two-photon absorption allowing efficient slicing up to mid-infrared frequencies.
    Full-text · Article · Jun 2014 · New Journal of Physics
  • Source
    • "Such field strengths are by far sufficient for nonlinear studies, and a range of fundamental physical phenomena such as impact ionization [9], side valley scattering [10], THz-induced optical Kerr effect in liquids [11], vibrational anharmonicities in molecular crystals [12], the dynamic Franz–Keldysh effect in multiple quantum wells [13] and quantum dots [14], and even THz-induced phase transitions [15] have been investigated in the low (<3 THz)-frequency range. Nonlinear two-dimensional spectroscopy on bulk InSb [16], dual quantum wells and multilayer graphene [17] have been demonstrated using THz transients in the 10–40 THz range. In principle, the bandwidth of the generated THz pulse can be as high as the bandwidth of the femtosecond pump source. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We use a broadband microbolometer array to measure the full three-dimensional (3D) terahertz (THz) intensity profile emitted from a two-color femtosecond plasma and subsequently focused in a geometry useful for nonlinear spectroscopic investigations. Away from the immediate focal region we observe a sharp, conical intensity profile resembling a donut, and in the focal region the beam collapses to a central, Lorentz-shaped profile. The Lorentzian intensity profile in the focal region can be explained by considering the frequency-dependent spot size derived from measurements of the Gouy phase shift in the focal region, and the transition from the donut profile to a central peak is consistent with propagation of a Bessel–Gauss beam, as shown by simulations based on a recent transient photocurrent model (You et al 2012 Phys. Rev. Lett. 109 183902). We combine our measurements to the first full 3D visualization of the conical THz emission from the two-color plasma.
    Full-text · Article · Jul 2013 · New Journal of Physics
  • [Show abstract] [Hide abstract]
    ABSTRACT: By using the intense THz pump-THz probe spectroscopy, we observed the collective Higgs amplitude mode of the BCS order parameter in a nonadiabatically-excited superconducting Nb1-xTixN films. The result opens a new pathway for ultrafast optical coherent control of macroscopic quantum states.
    No preview · Conference Paper · Jan 2013
Show more