Silicon double-injection electro-optic modulator with junction gate control

Abstract

Novel structures for carrier-induced electro-optical phase modulation in crystalline silicon are examined. A new dual-injection field-effect transistor structure for guided-wave light modulation at 1.3 μm is proposed and analyzed. It consists of an elongated cathode-anode-gate structure integrated in a rib waveguide. Dual-gate and single-gate control are considered. The overlap between the plasma charge density and the optical guided mode is computed. For a cathode-anode voltage of 0.32 V, the effective refractive index of the waveguide mode changes by ΔN=1×10−3 when the gate voltage is altered by 12 V. Numerical estimates of the bias current, pinchoff voltage, interaction length, and modulator speed are given.