(Color) (a) Simulated area charge density (i.e., volume charge density integrated over excitation depth) at (peak of excitation pulse) for injection current excitation in with parameters given in text. The same information is displayed as a surface plot and a contour plot. (b) Area charge density at .
(a) Calculated normalized total current for shift and injection current sources in with 10 and electron momentum scattering time for an incident optical pulse. (b) The corresponding terahertz electric fields.
Apparatus for recording terahertz radiation generated by induced currents in ; the OAPM are off-axis parabolic mirrors.
EO traces of terahertz radiation for the shift current excited in by linearly polarized pulses at with peak intensity of . The vertical arrows in the legend indicate that the beam is polarized along the optic axis with the current making use of the tensor element; the horizontal arrows indicate that the beam is polarized perpendicular to the optic axis, with the terahertz trace sensitive to any tensor. Flipping of arrows indicates reorientation of the sample by 180°.
EO traces of terahertz radiation produced by injection current excited in by , pulses with a peak intensity of and for oppositely handed circular polarizations. The inset shows the intensity dependence of the EO signal (dots) with the solid line indicating linear behavior.
Magnitude of and in as function of photon energy (solid dots and squares, respectively); the solid and dashed lines are guides to the eye.
EO traces of terahertz radiation corresponding to the shift current excited in by a optical pulse with and a peak intensity of for different sample orientations. The arrows in the legend correspond to sample orientation (see Fig. 1 for explanation). The inset shows the measured intensity dependence of terahertz amplitude (solids dots); the solid line corresponds to linear dependence.
EO traces of terahertz signal corresponding to the injection current excited in by a , optical pulse with a peak intensity of for different circular polarizations. The inset shows an intensity study with the solid line corresponding to linear dependence.
(a) EO traces of terahertz signal for injection and shift currents in using the EO crystal. (b) The corresponding terahertz spectra.
Summary of results for and .
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