OPTICAL FUNCTION ELEMENT

PROBLEM TO BE SOLVED: To provide an optical function element which has small stray light to have excellent noise characteristics, and is easy to manufacture. SOLUTION: The optical function element includes a light emitting element 12 as a light source, a dielectric substrate 14 having an optical waveguide 20 formed, and a light receiving element 16 which converts light into electricity, wherein light from the light emitting element 12 is modulated with an external electric signal and the modulated light is output in the form of an electric signal through the light receiving element 16. The optical waveguide 20 includes an input waveguide portion 20a formed on a surface 14a of the dielectric substrate 14, modulation portions 20b and 20c which branch off from the input waveguide portion 20a and are modulated with the external electric signal, and an output waveguide portion 20d connecting with the modulation portions. The light emitting element 12 and light receiving element 16 are disposed on the side of the reverse surface 14b of the dielectric substrate 14, and emit and receive light beams in a direction orthogonal to the top surface 14a and reverse surface 14b, respectively. Mirrors 26 and 28 are provided at a starting end of the input waveguide portion 20a and at an ending end of the output waveguide portion 20d. COPYRIGHT: (C)2009,JPO&INPIT