Optical second harmonic generation and its photoinduced dynamics in ferroelectric semiconductor Sn2P2S6

Study of the Crystalline State of MBE (013)HgCdTe/CdTe/ZnTe/GaAs Heterostructure Layers by the Second Harmonic Generation Method

“…The SH calculation using the non-linear susceptibility tensor χ x y z (ω) in the crystals of sphalerite or zinc blende (international classificationclass 43m) is described in detail in [30,31]. When comparing the calculation and experimental results of the azimuthal SH signal dependences in a specific geometry and for specific crystal slices, numerical modelling is applied [25][26][27][28][29][32][33][34].…”

“…The SHG can be used to perform express contactless measurements of the structural perfection of the crystal without an inversion center with the high local resolution in thin subsurface layers [30]. For the GaAs crystals, the epitaxial CdTe layers on the various substrates and the MBE MCT HES'es on the GaAs and Si substrates the SHG method has demonstrated the high efficiency and allowed obtaining new data in measuring the crystal perfection [31][32][33].…”

Highly sensitive express nonlinear optical diagnostics of the crystalline state of heterostructures such as sphalerite

“…The dependence of SHG components polarization intensity on the mutual orientation of the exciting radiation polarization relative to the crystallophysical axes, when the SH polarization, parallel or perpendicular to the azimuthally varying linear polarization of the exciting radiation (further as the text goesangular or azimuthal dependence) is registered, allows obtaining quantitative information about the crystalline state of the surface layer, its orientation and several other properties while comparing experimental and model data in a given local area, to an accuracy less than or equal to a degree [1][2][3][4][5][6][7][8][9][10][11]. The diagnostic capabilities of the SHG method are widely used, for example, when studying the electronic and magnetic properties of materials by the characteristics the of identified magnetically induced second optic harmonic generation in diamagnetic and paramagnetic semiconductors [12,13].…”

Ferroelectric Polarization Reversal vs Pump Spot Shape

“…The original proposal to switch the polarization by resonant excitation of the ferroelectric mode [11][12][13] has not yet been fully realized experimentally [14][15][16][17]. It was also shown that optical pumping with excitation of the electronic subsystem [18][19][20][21] leads only to a temporary decrease in polarization [22][23][24][25]. Following the rapid development and achievements of nonlinear phononics [26][27][28][29], it was proposed to pump the IR-active optical phonon mode, which is nonlinearly coupled with the ferroelectric soft mode [30].…”

“…In experiments with optical pumping [23][24][25], the penetration depth of the pump pulse varies from about 3 nm [25] upto 100 nm [24], depending on the crystal used. In this case, the depolarization factor should already be very small, and the depolarizing field is strongly reduced.…”