Author Affiliations
1State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China2Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China3School of Physics Science and Engineering, Tongji University, Shanghai 200092, China4Physics and Electronic Engineering Department, Xinxiang University, Xinxiang 453003, Chinashow less
Fig. 1. Experimental setup. The fundamental and SHG are linearly polarized in s-polarization direction. The mirror plane of Bi2Se3 is rotated to be parallel to the polarization of the pump field.
Fig. 2. HHG spectrum with and without the SHG, respectively; the intensity of the fundamental is 77 GW/cm2; gray line, the SHG intensity is 0; green line, the SHG intensity is 0.025 GW/cm2; ϕ = π. The small peak at 1.48 eV is the second-order diffraction of H9 from the grating-based spectrometer.
Fig. 3. Harmonic yield versus the phase delay of two-color laser fields. (a) Modulation of H4 for the SHG intensity of 0.025 GW/cm2 (blue square and line) and 1.2 GW/cm2 (orange square and line); (b), (c) Modulation of H5 (b) and H6 (c) with the same experimental condition as (a).
Fig. 4. Calculated high-harmonic spectra. (a) HHG from the surface states with and without the SHG; blue line, harmonic spectrum without the SHG; orange line, harmonic spectrum for the SHG intensity equal to 40 MW/cm2 and ϕ = 0.6π. (b) HHG from the bulk states with and without the SHG; blue line, harmonic spectrum without the SHG; orange line, harmonic spectrum for the SHG intensity equal to 40 MW/cm2 and ϕ = 0.6π.
Fig. 5. High-harmonic yield modulated with the phase delay of two-color laser fields. (a), (b) Modulation of H4 (a) and H5 (b) from the surface states, for the SHG intensity of 4 MW/cm2 (red line) and 40 MW/cm2 (blue line), respectively; (c), (d) modulation of H4 (c) and H5 (d) from the bulk states, for the SHG intensity of 4 MW/cm2 (red line), 40 MW/cm2 (blue line), and 400 MW/cm2 (purple line), respectively.
| Without SHG | With SHG |
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Inversion symmetry (bulk) | σ = 0, Δθ = 0; no even harmonics | σ ≠ 0, Δθ = 0; even harmonics; modulation, T2ω/2 | Inversion symmetry breaking (surface) | σ = 0, Δθ ≠ 0; even harmonics | σ ≠ 0, Δθ ≠ 0; even harmonics; modulation, T2ω |
|
Table 1. Summary of Modulation Results Dictated by Symmetry