Patent ID: 6373606
Filing Date: 2002-04-16
Classification: G01J,G02B,H01L

Abstract:
An optical demultiplexer, comprising:an optical fiber, a single collimator lens, a diffraction grating, and an array of photodetectors, wherein a light beam emitted from the optical fiber is demultiplexed by the collimator lens and the diffraction grating into light beams, and the light beams are focused by the collimator lens as beam spots deformed due to an aberration of an optical system of the optical demultiplexer onto the array photodetectors, and said photodetectors are arranged to accommodate and detect all the deformed focused beam spots, and wherein said array of photodetectors comprises a linear array of as many photodetectors as the number of demultiplexed channels in a direction in which the light beam is demultiplexed by said diffraction grating, and said diffraction grating has a diffraction order of m and a diffraction constant d, the center-to-center distance between adjacent ones of said photodetectors along the array of the photodetectors is represented by p, the focal length of said collimator lens is represented by f, the used wavelength is represented by &lgr;0, and the wavelength interval between the demultiplexed channels is represented by &Dgr;&lgr;, then the center-to-center distance p between adjacent ones of the photodetectors along the array of the photodetectors satisfies the following equation: p=mf&it;â€ƒ&it;Î”&it;â€ƒ&it;Î»d&it;1-(m&it;â€ƒ&it;Î»0(2&it;d)2)and wherein the width Wy of said photodetectors along the array thereof ranges from 0.2 to 0.9 p and the width Wx of said photodetectors in a direction perpendicular to the array thereof ranges from 1 Wy to 10 Wy.