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.
Waveguide coupler with diffraction grating which selectively inhibits coupling