Optical waveguide intensity modulator in silicon, based on carrier injection in a Si1−xGex pin heterostructure

A Si1−xGex pin optical waveguide modulator operating at a wavelength of λ = 1.3 μm was designed and demonstrated. The free carrier absorption by carriers injected into the i region under high forward bias was used to attenuate the guided mode intensity. Numerical simulations indicate that this structure can operate at speeds up to 200 MHz. A maximum modulation depth of 85% was measured for a 2 mm long waveguide using a peak modulation current of 4200 A cm−2.