Patent ID: 6853770

Claim:
A method of aligning and assembling an optical demultiplexer module having at least an input fiber, a collimator lens, a diffraction grating, and a photodetector array, comprising the steps of: (a) preparing a submodule A including said input fiber and said photodetector array which are fixed in respective positions, and a submodule B including said diffraction grating and said collimator lens which are fixed in respective positions; (b) preparing an alignment jig for allowing said submodules A, B to move independently of each other, and, when the submodules are held by said alignment jig, adjusting the submodules such that a reference surface of said submodule A and an alignment moving direction in which said submodule B is relatively movable for alignment have a predetermined relationship to each other; (c) fixing said submodule A to said adjustment jig such that a reference line of said photodetector array lies horizontally; (d) fixing said submodule B to said adjustment jig such that grooves of said diffraction grating extend vertically; and (e) applying light having a wavelength corresponding to one or more channels from said input fiber, and moving said submodule B with respect to said submodule A to align the submodules for maximizing a light output from a photodetector corresponding to said channel or channels.