Patent ID: 7680362

Claim:
An optical device, comprising: a first optical filter adapted to apply bandpass filtering to a first component of an optical input signal to produce a first filtered signal, wherein said first component has a first polarization; one or more polarization rotators adapted to change (i) the first polarization of the first filtered signal to a different second polarization and (ii) the second polarization of a second component of the optical input signal to the first polarization; and a second optical filter adapted to apply bandpass filtering to the second component having the resulting first polarization to produce a second filtered signal, wherein the optical device is adapted to combine the first and second filtered signals to produce a filtered output signal, wherein at least one of the first and second optical filters comprises: a first optical bandpass filter having a first free spectral range (FSR); and a second optical bandpass filter having a different second FSR and connected in series with the first optical bandpass filter so that an output port of the first optical bandpass filter is connected to an input port of the second optical bandpass filter.