An optical multiplexing and demultiplexing device of a type using a lens and a diffraction grating, which incorporates a waveguide array having waveguide channels with narrow spacings for facilitating high resolution, where the narrow spacings are realized by forming an etching groove between each adjacent...http://www.google.se/patents/US5917625?utm_source=gb-gplus-sharePatent US5917625 - High resolution optical multiplexing and demultiplexing device in optical communication system
