An optical modulator and a method for manufacturing an optical modulator are provided. The optical modulator includes a first waveguide, a second waveguide, a modulating portion connected between the first waveguide and the second waveguide, the modulating portion being configured to receive an input signal from the first waveguide, to modulate the input signal and to supply a corresponding modulated input signal as an output signal to the second waveguide, wherein the modulating portion includes a semiconductor substrate, one end thereof being coupled to the first waveguide, and a corresponding opposite end thereof being coupled to the second waveguide, a Germanium rib provided on the substrate such that the input signal propagates through the Germanium rib along a longitudinal axis thereof, and a first electrode and a second electrode respectively provided on the substrate, wherein the Germanium rib is provided between the first electrode and the second electrode, and wherein the first electrode and the second electrode are configured to apply an electrical field to the Germanium rib in order to modulate the input signal propagating through the Germanium rib.