Terahertz-field-induced second optical harmonic generation from Si(111) surface

Multi‐Scale Modeling of Surface Second‐Harmonic Generation in Centrosymmetric Molecular Crystalline Materials: How Thick is the Surface?

“…Taking into account electric quadrupoles in the simulations would also lead to an SHG signal from the bulk, see Ref. [8][9][10]. Considering thin films, however, the surface contribution is expected to dominate.…”

THz-near IR hyper-Raman surface spectroscopy of silicon wafer surface

“…Hz induced second harmonic generation is a well know technique making it possible to record second harmonic generation (SHG) in a centrosymmetric material such as silicon [1]. At the surface of silicon different processes have been shown to account for THz induced SHG [2]- [4]. The generated field writes ESHG (2±)~ (3) ( ±) E()E 2 () where E(), E() and  (3) (  ±) are the electric field of the THz and optical pulses and the third-order susceptibility of the studied material, respectively.…”

Cubic Nonlinearity of Tellurite and Chalcogenide Glasses: Terahertz-Field-Induced Second Harmonic Generation vs. Optical Kerr Effect

“…Superstrong (above the DC-field breakdown threshold) terahertz fields (~20 MV/cm) were employed for studying SHG in p-doped Si under below-band-gap optical excitation [33]. TFISHG in reflection geometry was used to characterize the Si(111) surface under above-band-gap optical excitation with a moderate terahertz field (~300 kV/cm) [34]. The specific feature of the TFISHG measurements, shown in Refs.…”

“…The specific feature of the TFISHG measurements, shown in Refs. [31,34], is the influence of ambient gas (air) on the detected second harmonic (SH) signal (this influence was also discussed in regards to EFISHG [35]). In the previous studies, due to a rather strong SH signal from the sample or/and some overlapping geometry of the fundamental optical and terahertz pulses, the SHG from ambient gas could be neglected or strongly suppressed by using helium gas instead of air [31,34].…”

“…[31,34], is the influence of ambient gas (air) on the detected second harmonic (SH) signal (this influence was also discussed in regards to EFISHG [35]). In the previous studies, due to a rather strong SH signal from the sample or/and some overlapping geometry of the fundamental optical and terahertz pulses, the SHG from ambient gas could be neglected or strongly suppressed by using helium gas instead of air [31,34]. However, in the case of a small SH signal from the sample (due to its small nonlinearity), even rather weak generation from the ambient gas may be significant.…”