CMOS-compatible polarization-diverse tunable optical bandpass filter
First Claim
1. 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.
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Abstract
According to one embodiment, an optical filter has a polarization rotator and two instances of an optical bandpass filter (OBPF). The first instance of the OBPF processes a TE-polarized component of an optical input signal to produce a first filtered signal. The polarization rotator then transforms the TE polarization of the first filtered signal into the TM polarization. The polarization rotator also transforms the polarization of a TM-polarized component of the optical input signal into the TE polarization. The second instance of the OBPF processes the resulting TE-polarized signal to produce a second filtered signal. The first and second filtered signals having TM and TE polarizations, respectively, are then combined to produce a filtered output signal.
16 Citations
20 Claims
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1. An optical device, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of processing optical signals, comprising:
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applying 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; changing the first polarization of the first filtered signal to a different second polarization; changing the second polarization of a second component of the optical input signal to the first polarization; applying bandpass filtering to the second component having the resulting first polarization to produce a second filtered signal; and combining the first and second filtered signals to produce a filtered output signal, wherein at least one of the applying steps comprises passing the respective component through (i) a first optical bandpass filter having a first free spectral range (FSR) and (ii) 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.
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Specification