Patent ID: 7391973

Claim:
An apparatus for selectively adjusting power levels of component signals of a wavelength division multiplexed (WDM) signal, the apparatus comprising: a circulator configured to receive the WDM signal via a first port and outputting the WDM signal via a second port; a collimating lens configured to receive the WDM signal from the circulator and to collimate the WDM signal; a first filter for receiving the WDM signal from the collimating lens and for modulating the component signals according to a static attenuation profile, thereby providing coarsely modulated component signals, wherein the static attenuation profile includes a predetermined function in which attenuation varies as a function of the wavelength of the component signal; a de-multiplexing device configured to receive the coarsely-modulated component signals from the first filter and for diffracting the coarsely-modulated component signals at different angles; a transform lens configured to receive the diffracted coarsely-modulated signals from the de-multiplexing device and to map the coarsely-modulated signals onto different positions in a plane; and a second filter configured in the plane to receive the coarsely-modulated component signals mapped to the different positions in the plane and to modulate the coarsely-modulated component signals according to a dynamic attenuation profile, thereby providing finely-modulated component signals, wherein the second filter includes a dynamic gain equalizer comprising a diffractive light modulator, the diffractive light modulator including a plurality of elements configured to receive de-multiplexed component signals, wherein each element is controllable to selectively modulate each of the component signals according to the dynamic attenuation profile, wherein the first filter comprises a transparent glass lid with thin-film coatings covering the diffractive light modulator of the second filter.