Silicon Mach-Zehnder waveguide interferometers based on the plasma dispersion effect

Silicon Mach-Zehnder waveguide modulators have been fabricated and operation characterized at the wavelength of 1.3 μm. Device operation is based on the free-carrier-induced change in the refractive index of silicon. Modulation depths of -4.9 dB and response times τresponse<50 ns have been achieved at λ=1.3 μm for an injected carrier density of 6.5×1017 cm-3.