Patent ID: 6665467
Filing Date: 2003-12-16
Classification: G02B

Abstract:
An optical wavelength filter, comprising:first and second optical couplers for propagating wavelength division multiplexing (WDM) light comprising a plurality of wavelengths, exciting multiple modes of light comprising high-order modes of light for light of each wavelength of said WDM light, and providing a predetermined phase difference between different modes of light of said multiple modes of light; and a mode converter, which is arranged between said first and second optical couplers, and which performs mode conversion between different-order modes of light belonging to a selected specific wavelength of light from among said multiple modes of light excited by said optical couplers, wherein said mode converter comprises a multimode waveguide, and a plurality of rows of diffraction gratings which are arranged in said multimode waveguide so as to form a periodic structure along in optical wave guiding direction in said multimode waveguide, the rows of diffraction gratings extending in parallel with respect to each other while being mutually staggered by a half period.