Investigation on the electric-field-induced Pockels effect and optical rectification in near-intrinsic silicon samples

Based on the classical polarization theory, we studied and specified the physical mechanism of the electric-field-induced (EFI) Pockels effect and optical rectification in the space charge region of a near-intrinsic silicon sample with the planar capacitor structure. Especially, the effect of the applied DC bias on these EFI effects was investigated. The results show that the electro-optic signal from Pockels effect in silicon linearly increases with the applied DC voltage and the modulating voltage, and the signal of optical rectification is linearly enhanced by the DC bias as well, but the polarization characteristic of optical rectification does not vary. The enhancement of these EFI effects is mainly owed to the strengthening of the built-in field and the extension of the space charge region in the silicon sample. The Kerr effect of silicon was also detected and contrasted against the EFI Pockels effect, and it is verified that the EFI Pockels effect is much stronger than the Kerr effect in the silicon sample. These EFI effects are significant for the development of silicon photonics or silicon optoelectronics.

► DC electric fields can induce Pockels effect and optical rectification in silicon.
► Electric-field-induced (EFI) effects can be explained by the polarization theory.
► EFI Pockels effect is linearly enhanced by external DC voltage.
► Signals of EFI optical rectification linearly increase with external DC voltage.
► Reasons for the enhancement of these EFI effects are discussed qualitatively.