OPTICAL WAVEGUIDE ELEMENT HAVING DIRECTIONAL COUPLER FOR REDUCING BIDIRECTIONAL CROSS TALK; INCLUDING THE SECOND DUMMY WAVEGUIDE ADJACENT TO THE FIRST WAVEGUIDE FOR MODE COUPLING

摘要

PURPOSE: An optical waveguide element having a directional coupler is provided to reduce a bidirectional cross talk by forming a reflector and a second dummy waveguide on an end portion of the first dummy waveguide. CONSTITUTION: An optical waveguide element having a directional coupler includes first and second waveguides(101,102), a first dummy waveguide(121a), a reflector(104), and a second dummy waveguide(103). The first and second waveguides are arranged to be adjacent to each other on a predetermined range for mode coupling. The first dummy waveguide is extended from an end of the second waveguide. The reflector is implemented on an end portion of the first dummy waveguide. The second dummy waveguide is extended from the reflector and is arranged to be adjacent to the first dummy waveguide for mode coupling. An optical signal propagating from the second waveguide to the first dummy waveguide sequentially passes by the reflector and the second dummy waveguide and then vanishes.