Abstract: This invention provides a novel method and apparatus which use a wavelength-dispersing means such as a diffraction grating to spatially separate a multi-wavelength optical signal along with a reference signal by wavelength into multiple spectral channels and a reference spectral component in a spectral array with a predetermined relative alignment. By aligning the reference spectral component at a predetermined location, the spectral channels simultaneously impinge onto designated locations, e.g., on an array of beam-receiving elements positioned in accordance with the spectral array. The reference spectral component may be further maintained at the predetermined location by way of servo-control, thereby ensuring that the spectral channels stay aligned at the designated locations. The present invention can be used to construct a new line of servo-based optical systems, including spectral power monitors and optical multiplexers/demultiplexers, for WDM optical networking applications.

Abstract: This invention provides a spectral power monitoring apparatus that uses a diffraction grating to separate a multi-wavelength optical signal along with a reference signal by wavelength into multiple spectral channels and a reference spectral component having a predetermined relative alignment, impinging onto an array of optical power sensors. The optical power sensor array may be configured such that the power levels of the spectral channels impinging onto the optical power sensor array can be related to the electrical signals thus produced by a predetermined conversion matrix. The spectral power monitoring apparatus of the present invention further includes an alignment compensation unit, which monitors the real-time impinging position of the reference spectral component and ensures that the corresponding conversion matrix is used for converting the measured electrical signals to the optical power levels of interest.