| 摘要 |
The method for filtering an optical signal comprising a plurality of channels lying on a grid of optical frequencies equally spaced by a given frequency spacing and occupying an optical bandwidth, comprises: a) splitting the optical signal into a first and a second portion spatially separated, wherein the first portion comprises the channels which lie on a first sub-grid comprising a first set of the optical frequencies equally spaced by the double of the frequency spacing and the second portion substantially comprises the remaining channels; b) operating a first optical filter comprising a plurality of resonators, wherein a first resonator of the plurality is optically coupled to the first portion and the remaining resonators are optically coupled in series to the first resonator, so that a respective resonance of each one of the plurality of resonators falls within a first frequency band having bandwidth less than or equal to 15 GHz and comprising a first channel belonging to the first portion; c) operating a second optical filter comprising a plurality of respective resonators, wherein a respective first resonator of the plurality is optically coupled to the second portion and the remaining resonators are coupled in series to the first resonator, so as to obtain a first separation between each resonance of at least one resonator of the second optical filter falling within the optical bandwidth and a respective resonance of at least another different resonator of the second optical filter nearest to said each resonance, the first separation being greater than or equal to 25 GHz; and d) recombining the first and second filtered portions. A corresponding optical device for filtering an optical signal is disclosed.
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