Abstract

Silicon is a centrosymmetric crystal, so it does not exhibit a Pockels (linear electro-optic) effect. It does, however, exhibit a free-carrier effect in which both the real and the imaginary parts of the refractive index are changed when carriers are introduced either through doping or injection. Demonstrations of the use of the free-carrier effect in silicon include direct amplitude modulation from carrier injection in a forward biased p-i-n (Ref. ¹) or MIS (Ref. ²) diode as well as amplitude modulation from a phase shift in a 2 × 2 switch³ and an interferometric modulation scheme.⁴ These investigations required large current densities (greater than 100 A/cm²) to achieve modulation of 10%-60%. Furthermore, the size of the real index change was not reported.

© 1990 Optical Society of America