DC-induced generation of the reflected second harmonic in silicon

DC-induced generation of the reflected second harmonic is experimentally observed on the surface of a centrosymmetric silicon single crystal. A direct current with a surface density of j _max ~ 10³ A/cm² violates the symmetry of the electron distribution function and induces the optical second harmonic with an intensity corresponding to the dipole quadratic susceptibility χ^(2)d (j _max) ~ 3 × 10⁻¹⁵ m/V.