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A fourfold-azimuthal dependence of terahertz radiation from polished mono-crystalline (100) silicon is observed firstly. This phenomenon is explained by the electric quadrupole-magnetic dipole, which resemble second harmonic generation from (100) silicon.
Electro-optic effects of PbZr0.52Ti0.48O3(PZT) and BaTiO3(BTO) ferroelectric thin films in the terahertz frequency range are studied with high-sensitive terahertz time-domain spectroscopy (THz-TDS). A linear response of PZT film with the linear electro-optic coefficient rc=6.73×10–11 m/V, and a quadratic response of BTO film with the second-order electro-optic coefficient Rc=1.42×10–17 m2/V2, are...
The paper addresses the feature selection based on Neighborhood Rough Set (NRS) used as evaluation function and Ant Colony Optimization (ACO) as generation procedure. A NRS-based measure is employed as heuristic information of ACO. For the weakness of setting a specified value to the size of neighborhood, a new standard deviation based value is advanced to be the size of neighborhood. Four datasets...
Currently, delegation models with time constraints are focused on RBAC and DAC models and doesn't support TRBAC (task_role_based access control) model. This paper presents a delegation model with time constraints for TRBAC model, called TTRBDM. TTRBDM uses time constraints and task revocation to control delegation. Authors give the conceptions of the task delegation and the task revocation, formally...
Fundamental and high-order phonon-phonon interactions dominate the far infrared absorption and dispersion spectrum of most semiconductors and dielectrics. We present the detailed investigation of the temperature dependence of the dielectric function of the semiconductor GaSe in the frequency range below 4 THz, between 100 K and 310 K, using terahertz time-domain spectroscopy (THz-TDS) technique. Combined...
This paper presents the refractive index, absorption coefficient of layered GaSe crystal by means of terahertz time-domain spectroscopy. A unique resonance peak was observed at 0.59 THz (19.6 cm-1 ), which attributes to the E' phonon mode of epsiv-GaSe.
Terahertz (THz) wave generation based on the difference-frequency mixing in the GaSe crystal was investigated theoretically and experimentally. An orthogonally polarized dual-wavelength optical parametric oscillator (OPO) with two KTiOPO4 crystals was used as the pump lights. Widely tunable terahertz waves were generated using the collinear phased-matched configuration. The spectral distribution of...
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