A fast silicon-on-insulator (SOI) waveguide-based optical device enhanced with minority charge carrier lifetime modifiers enables faster modulation speeds in optical attenuators, optical intensity/phase-modulators, and optical switches whose operation principles are based on free-carrier injection into a waveguide. The waveguide is doped with gold (Au) or platinum (Pt) such that when a drive voltage (applied to the device) is turned off, the minority charge carriers rapidly annihilate because gold doping reduces the minority carrier lifetime, which improves transient characteristics of the optical device. Integration of the fast active device with passive devices such as WDM demultiplexers/multiplexers on the SOI optical waveguide platform enables realization of monolithic integrated optical components for advanced functionality such as dynamic spectral equalization.