Patent ID: 8406579

Claim:
A wavelength division multiplexing and optical modulation apparatus including: at least two modulation region-added grating-assisted cross-state directional coupler units each including: a modulation region-added cross-state directional coupler including an input waveguide and an output waveguide, wherein the modulation region-added cross-state directional coupler is a region in which an end of the output waveguide extends parallel to an end of the output waveguide of the other modulation region-added grating-assisted cross-state directional coupler, wherein the length of the region in which the output waveguides extend parallel to each other is same or larger than the length of the grating, wherein the input waveguide is connected to the output waveguide of the other modulation region-added grating-assisted cross-state directional coupler; a grating located in a portion of the modulation region-added cross-state directional coupler in which the output waveguides and extend parallel to each other; and a modulation region in which the output waveguide extends parallel to the output waveguide of the other modulation region-added grating-assisted cross-state directional coupler unit; and a modulation region-added cross-state directional coupler unit connected to the modulation region-added grating-assisted cross-state directional coupler unit, wherein the modulation region-added cross-state directional coupler unit includes: an output waveguide connected to the input waveguide of the last one of the modulation region-added grating-assisted cross-state directional coupler units; an input waveguide including an end extending parallel to an opposite end of the output waveguide thereof; and a modulation region in which the output waveguide thereof and the input waveguide thereof extend parallel to each other.