Measurement of electro-optic effects in near-intrinsic silicon

The electro-optic effects in silicon include Kerr effect, plasma dispersion effect, and Franz-Keldysh effect etc.. Silicon does not have the linear electro-optic effect in the bulk because of the inversion symmetry, which restricts the development of the silicon-based optoelectronics and silicon photonics. However, the electric field can destroy the inversion symmetry of silicon, and produce so-called electric-field-induced linear electro-optic effect. In intrinsic or near-intrinsic silicon, these electro-optic effects exist simultaneously. In this paper, a transverse electro-optic modulation system was designed to detect these electro-optic effects. The electric-field-induced linear electro-optic effect was demonstrated in the space charge region of silicon sample and distinguished from Kerr effect based on the different frequency response. The relationship between the linear electro-optic signal and the azimuth angle of the analyzer was measured too, which was used for distinguishing the electric-field-induced linear electro-optic effect from the plasma dispersion effect. The results showed that the electric-field-induced linear electro-optic effect was stronger than Kerr effect and the plasma dispersion effect in the near-intrinsic silicon samples.