Electroabsorption duplexer

An electroabsorption duplexer comprising:

• a substrate;
• a separation area comprising a first epitaxial layer formed of at least one material layer on the substrate, the first epitaxial layer functioning as a first optical waveguide;
• an optical detection/modulation unit comprising a second epitaxial layer formed of at least one material layer on the first epitaxial layer to detect and modulate an optical signal, the second epitaxial layer functioning as a second optical waveguide;
• and
• an optical amplification unit disposed at each both sides of the optical detection/modulation unit comprising the second optical waveguide and a third epitaxial layer formed of at least one material layer on the second epitaxial layer to amplify an optical signal, the third epitaxial layer functioning as a third optical waveguide,
• wherein the optical amplification unit is electrically separated from the optical detection/modulation unit by the separation area and is disposed on at least one side of the optical detection/modulation unit
• wherein an effective refractive index of the optical waveguides increases in order of the first optical waveguide, the second optical waveguide, and the third optical waveguide, the cross-sections of the optical waveguides form a W shape as whole in a direction in which the optical mode propagates, and the optical mode moves in a direction from top to bottom and from bottom to top according to the W shape such that the W shape creates the electrical separation of the optical amplification unit and the optical detection/modulation unit.