Waveguide coupler with diffraction grating which selectively inhibits coupling

摘要

PCT No. PCT/GB94/02601 Sec. 371 Date Oct. 16, 1996 Sec. 102(e) Date Oct. 16, 1996 PCT Filed Nov. 29, 1994 PCT Pub. No. WO95/14946 PCT Pub. Date Jun. 1, 1995A waveguide coupler comprises at least a first waveguide coupled at a coupling region to a second waveguide such that at least a part of radiation propagating along the first waveguide is coupled into the second waveguide. The second waveguide comprises a diffraction grating disposed at the coupling region to inhibit coupling of radiation from the first waveguide into the second waveguide at wavelengths characteristic of the diffraction grating.