Double-layered antisymmetric two mode Bragg gratings
AssigneeCisco Technology, Inc.
InventorsTao Ling, Ravi S. Tummidi, Shiyi Chen
Life of this patent
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Abstract
Embodiments herein describe a dual-layer Bragg grating that can be used as a dual-bandpass filter. In one embodiment, the dual-layer Bragg grating comprises at least two layers, each having an anti-symmetrical structure. In addition, the anti-symmetrical structures can have different pitches which are tuned to different bands. That is, the pitch of the anti-symmetrical structure in one layer can be set to reflect a first band in a received optical signal while the pitch of the anti-symmetrical structure in the other layer is set to reflect a second band in the received optical signal.
Claims20
A Bragg grating, comprising:
- a first layer comprising a first anti-symmetrical structure in a first plane parallel with a top plane with a first pitch, wherein the first layer further comprises an input configured to receive an optical signal at a first end of the Bragg grating;
- and
- a second layer comprising a second anti-symmetrical structure in a second plane parallel with the top plane with a second pitch that is different than the first pitch, wherein the first layer is disposed between the second layer and the top plane, wherein the second layer further comprises:
- a first mode transition disposed in the second layer at the first end of the second layer;
- and
- a second mode transition disposed in the second layer at a second end of the second layer opposite the first end of the second layer.
A photonic chip comprising:
- an input waveguide configured to receive an optical signal;
- a first layer comprising a first anti-symmetrical structure with a first pitch in a first plane parallel with a top layer in a top plane, wherein the first layer is coupled to the input waveguide, and wherein the first layer receives the optical signal from the input waveguide, and
- a second layer parallel with the top layer in the top plane and comprising a second anti-symmetrical structure partially overlapping the first layer, wherein the second layer has a second pitch that is different than the first pitch, and wherein the first and second layers are tuned to reflect different bands contained in the optical signal, wherein the first layer is disposed between the second layer and the top plane, and wherein the second layer further comprises:
- a first mode transition disposed in the second layer at a first end of the second layer;
- and
- a second mode transition disposed in the second layer at a second end of the second layer opposite the first end of the second layer.
A passband filter comprising:
- an input configured to receive an optical signal comprising at least three bands;
- a dual-layer Bragg grating configured to receive the optical signal and reflect at least two of the at least three bands and permit at least one of the at least three bands to pass through;
- a first optical coupler disposed between the input and the dual-layer Bragg grating;
- a Bragg grating configured to receive the at least two bands reflected by the dual-layer Bragg grating through the first optical coupler, wherein at least one of the at least two bands reflected are permitted to pass through the Bragg grating and at least one of the at least two bands reflected are further reflected, and wherein the Bragg grating is different from the dual-layer Bragg grating;
- a second optical coupler disposed between the first optical coupler and the Bragg grating;
- a first output configured to output the at least one of the at least two bands reflected that are further reflected through the second optical coupler from the Bragg grating;
- a second output configured to output the at least one of the at least two bands permitted to pass through the Bragg grating;
- and
- a third output configured to output the at least one band that passed through the dual-layer Bragg grating.
Dependencies are inferred from the claim text.