Investigation of Si(111) by Terahertz-Field-Induced Optical Second Harmonic Generation

Terahertz-field-induced optical second harmonic generation from high-resistivity Si (111) was investigated both experimentally and theoretically. The azimuthal dependences of the second-harmonic (SH) signal for different polarizations of terahertz, fundamental and SH optical fields were analytically derived and experimentally verified. The dominance of build-in electric field induced source over surface/bulk-quadruple sources of SH generation was shown for the sample. The build-in electric field was estimated as 130 kV/cm. The relations between components of third-order nonlinear tensor were obtained.