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Ding C.,Henan University | Yu R.,Wuhan Institute of Technology | Li J.,Huazhong University of Science and Technology | Li J.,MOE Key Laboratory of Fundamental Quantities Measurement | And 2 more authors.
Journal of Applied Physics | Year: 2014

Unusual dispersion relation of graphene nanoribbons for electrons can lead to an exceptionally strong optical response in the infrared regime and exhibits a very good tunable frequency. According to quantum optics and solid-material scientific principles, here we show the possibility to generate ultraslow infrared bright and dark solitons in graphene under the action of strong magnetic and infrared laser fields. By means of quantum-mechanical density-matrix formalism, we derive the equations of motion that govern the nonlinear evolution of the probe-pulse envelope in this scheme. It is found that, by properly choosing the parameters of the system, the formation and ultraslow propagation of infrared spatial solitons originate from the balance between nonlinear effects and the dispersion properties of the graphene under infrared excitation. Moreover, the unique electronic properties and selection rules near the Dirac point provide more freedom for us to study the linear and nonlinear dynamical responses of the photonics and graphene system. These results may have potential applications in telecommunication and optical information processing. © 2014 AIP Publishing LLC. Source


Wang Z.,Huazhong University of Science and Technology | Lan P.,Huazhong University of Science and Technology | Luo J.,Huazhong University of Science and Technology | He L.,Huazhong University of Science and Technology | And 3 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We theoretically investigate the high-order harmonic generation (HHG) in a two-color multicycle inhomogeneous laser field. The results show that the ionization, acceleration, and recombination of the electrons in the HHG process can be simultaneously controlled with the combination of the temporal waveform synthesis and spatial nonhomogeneity of the laser field. Based on the quantum-mechanical and classical models, the physical mechanism of the supercontinuum generation in such a temporally and spatially shaped field is analyzed and discussed. In contrast to the case of the fundamental field alone, the supercontinuum in the two-color inhomogeneous field shows a constant intensity, a higher yield, and a broader bandwidth, which is beneficial for the efficient generation of broadband-isolated attosecond pulses from multicycle laser fields. © 2013 American Physical Society. Source


Qin M.,Huazhong University of Science and Technology | Zhu X.,Huazhong University of Science and Technology | Zhang Q.,Huazhong University of Science and Technology | Zhang Q.,MOE Key Laboratory of Fundamental Quantities Measurement | And 2 more authors.
Optics Letters | Year: 2012

We theoretically demonstrate a scheme for tomographic reconstruction of asymmetric molecular orbitals based on high-order harmonic generation with a two-color multicycle laser field. It is shown that by adjusting the relative phase of the two fields, the returning electrons can be forced to recollide from one direction for all the orientations of molecules. Thus, the reconstruction of the asymmetric orbitals can be carried out with multicycle laser field. This releases the stringent requirement of a single-cycle pulse with a stabilized and controllable carrier-envelope phase for the tomographic imaging of asymmetric molecular orbitals. © 2012 Optical Society of America. Source


Hong Z.,Huazhong University of Science and Technology | Zhang Q.,Huazhong University of Science and Technology | Zhang Q.,MOE Key Laboratory of Fundamental Quantities Measurement | Lu P.,Huazhong University of Science and Technology | Lu P.,MOE Key Laboratory of Fundamental Quantities Measurement
Optics Express | Year: 2013

A novel compact dual-crystal optical parametric amplification (DOPA) scheme, collinearly pumped by a Ti:sapphire laser (0.8 μm), is theoretically investigated for efficiently generating broadband IR pulses at non-degenerate wavelengths (1.2 μm∼1.4 μm and 1.8 μm∼2.1 μm). By inserting a pair of barium fluoride (BaF2) wedges between two thin β -barium borate (BBO) crystals, the group velocity mismatch (GVM) between the three interacting pulses can be compensated simultaneously. In this case, the obtained signal spectrum centered at 1.3 μm is nearly 20% broader and the conversion efficiency is increased, but also the pulse contrast and beam quality are improved due to the better temporal overlap. Furthermore, sub-two-cycle idler pulses with carrier-envelope phase (CEP) fluctuation of sub-100-mrad root mean square (RMS) can be generated. Because a tunable few-cycle IR pulse with millijoule energy is attainable in this scheme, it will contribute to ultrafast community and be particularly useful as a driving or controlling field for the generation of ultrafast coherent x-ray supercontinuum. © 2013 Optical Society of America. Source


Qin M.,Huazhong University of Science and Technology | Zhu X.,Huazhong University of Science and Technology | Liu K.,Huazhong University of Science and Technology | Zhang Q.,Huazhong University of Science and Technology | And 3 more authors.
Optics Express | Year: 2012

The influence of the orbital symmetry on the ellipticity of the high-order harmonics is investigated. It is found that the ellipticity maps have distinct shapes for the molecular orbitals with different symmetry. Our analysis shows that the feature of the harmonic ellipticity map is essentially determined by the nodal structure of the nonsymmetric orbital. The results indicate that the molecular-orbital geometry is imprinted on the ellipticity of the high-order harmonics, which invites the use of ellipticity measurements as a probe of the orbital structure for polar molecules. © 2012 Optical Society of America. Source

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