Patent ID: 7155088

Claim:
An optical modulator comprising: an optical waveguide formed by laminating on a substrate a core layer and a pair of cladding layers sandwiching the core layer, the optical waveguide including an input-side single-mode waveguide for propagating inputted light at single mode, a multi-mode waveguide for propagating the light propagated from the input-side single-mode waveguide at a plurality of guided modes, the light being propogated through the multimode waveguide, and an output-side single-mode waveguide for propagating the light propagated from the multi-mode waveguide at single mode to output the light; a lower electrode layer disposed below the multi-mode waveguide; and an upper electrode disposed above the multi-mode waveguide, the upper electrode cooperating with the lower electrode layer to apply at least one of an electric field and heat to the multi-mode waveguide, wherein a phase of each of the plurality of guided modes propagating through the multi-mode waveguide is modulated by applying at least one of an electric field and heat to the multi-mode waveguide, and intensity of the light outputted from the output-side single-mode waveguide is modulated by an interference of the plurality of guided modes which are phase-modulated.