Demultiplexer and its assembly device

A plurality of light receiving and emitting elements (1-5), the optical path connecting the plurality of light beam branching element for reflecting the remainder is transmitted through a portion of the incident light beam (11 to 14), and a corresponding optical element and the light branching element a plurality of coupling elements (6-10) which is arranged in, and a waveguide element disposed on an optical path before entering the reflected light from a certain light beam branching element other light branching element (15-18) It is provided. All binding elements are integrally formed in a single coupling element block (25). Thus, suppressing an increase in assembly time and the manufacturing cost can be suppressed. Further, by using a spherical mirror design parameters is small as a coupling element, the yield is higher the coupling element to form an array into a single block. Further, using a concave mirror as a wave elements, by arranging all of the guided devices in a single waveguide element blocks, the alignment tolerance of the waveguide element blocks becomes loose, the assembly is facilitated.