This invention provides a method and apparatus for spectral power
monitoring by use of a polarization diversity scheme. In the present
invention, a multi-wavelength optical signal is first decomposed into
first and second polarization components, and the second polarization
component is subsequently rotated by 90-degrees, prior to impinging onto a
diffraction grating that provides a higher diffraction efficiency for the
first polarization component. The diffraction grating separates the first
and second polarization components by wavelength respectively into first
and second sets of optical beams, impinging onto an array of optical power
sensors. The inventive optical spectral power monitoring apparatus thus is
able to minimize the insertion loss, while providing enhanced spectral
resolution. Further, by modulating the first and second sets of optical
beams prior to impinging onto the optical power sensor array, the present
invention enables an optical power spectrum associated with each
polarization component in the multi-wavelength optical signal to be
separately determined.
