Abstract: The invention relates to a planar lightwave circuit including a pair of opposed concave reflective diffraction gratings sharing the same focal line, which separates first and second slab waveguide regions. The ends of input and output waveguides are positioned along the focal line for launching and receiving light directed by one or both of the diffraction gratings. The invention enables light within in a certain wavelength range to be launched from an input waveguide, directed by a single diffraction grating, and output waveguides, all within a single slab waveguide region, while light within another wavelength range will be directed from one diffraction grating to another for output waveguides in a different slab waveguide region.

Abstract: A method for integrating power monitoring capabilities with passive demultiplexing operations, utilizing the high-order diffraction from an optical diffraction grating. The technique helps avoid insertion loss and polarization dependent loss penalties, and device size penalties, typically incurred with optical taps and multiple diffraction gratings. The technique can also be modified slightly to provide information on channel wavelength and optical signal-to-noise-ratio, as well as channel power.

Abstract: An optical performance monitor for measuring the performance of optical networks has an echelle grating for demultiplexing an input beam into a plurality of wavelengths that are focused onto an array of divided output waveguides. Each divided output waveguide is positioned to receive a corresponding demultiplexed wavelength from the echelle grating or other waveguide multiplexer device. The divided output waveguides laterally separate the corresponding demultiplexed wavelength into a first and second portions. A detector array is positioned to receive the respective portions of the demultiplexed wavelengths and by comparing their relative intensity it is possible to detect any drift in the nominal wavelengths of the channels.