Microring resonator-based optical device with improved linearity
An example microring resonator (MRR) based optical device having improved linearity is presented. The optical device includes a first MRR and a first bus waveguide optically coupled to the first MRR. Further, the optical device includes a second MRR optically coupled to the first MRR, and a second bus waveguide optically coupled to the second MRR. The first MRR and the second MRR are formed between the first bus waveguide and the second bus waveguide. The optical coupling between the first MRR and the second MRR increases the linearity in the optical output of the optical device.
1 . An optical device comprising:
a first microring resonator (MRR);
a first bus waveguide optically coupled to the first MRR;
a second MRR optically coupled to the first MRR; a second bus waveguide optically coupled to the second MRR, wherein the first MRR and the second MRR are formed between the first bus waveguide and the second bus waveguide; and
an optical distributor coupled to the first bus waveguide and the second bus waveguide and comprising two input ports and two output ports, wherein the optical distributor receives an input light through one of the two input ports, generates a first light stream and a second light stream from the input light, and feeds the first light stream to the first bus waveguide via a first output port of the two output ports and the second light stream to the second bus waveguide via a second output port of the two output ports,
wherein the first MRR and the second MRR are designed to have equal diameters, thicknesses, and widths so that the first MRR and the second MRR have the same resonant wavelength, causing a superlinear transmission region of the second MRR to align with a resonant wavelength of the first MRR.
2 . The optical device of claim 1 , wherein the first MRR is formed between the first bus waveguide and the second MRR, and the second MRR is formed between the first MRR and the second bus waveguide.
3 . The optical device of claim 1 , wherein the first bus waveguide comprises a first output port and the second bus waveguide comprises a second output port, and wherein the first output port and the second output port are formed on a same side of the first MRR and the second MRR thereby reducing routing complexities in optical systems that use the optical device.
4 . The optical device of claim 1 , wherein the second MRR is over-coupled to the second bus waveguide, resulting in the superlinear transmission region comprising superlinear phase variations near a resonant wavelength of the second MRR.
5 . The optical device of claim 1 , further comprising a phase shifter formed along one or both of the first MRR or the second MRR to control a phase angle of light propagating inside the first MRR or the second MRR to align the superlinear transmission region of the second MRR with a resonant wavelength of the first MRR.
6 . The optical device of claim 4 , wherein optical coupling between the first MRR and the second MRR and an alignment of the superlinear transmission region of the second MRR with a resonant wavelength of the first MRR results increases linearity in an optical output signal of the optical device.
7 . The optical device of claim 6 , wherein increase in the linearity of the optical output signal increases bit precision of the optical device.
8 . A coherent optical neural network (ONN) system, comprising:
a first optical device; and
a second optical device optically coupled to the first optical device,
wherein each of the first optical device and the second optical device comprises:
a first microring resonator (MRR);
a first bus waveguide optically coupled to the first MRR and comprising a first output port;
a second MRR optically coupled to the first MRR;
a second bus waveguide optically coupled to the second MRR and comprising a second output port, wherein the first MRR and the second MRR are formed between the first bus waveguide and the second bus waveguide; and
an optical distributor coupled to the first bus waveguide and the second bus waveguide and comprising two input ports and two output ports, wherein the optical distributor receives an input light through one of the two input ports, generates a first light stream and a second light stream from the input light, and feeds the first light stream to the first bus waveguide via a first output port of the two output ports and the second light stream to the second bus waveguide via a second output port of the two output ports,
wherein an input port of the two input ports of the optical distributor of second optical device is connected to one of the first output port and the second output port of a first optical device to receive an optical output signal of the first optical device;
wherein the first MRR and the second MRR are designed to have equal diameters, thicknesses, and widths so that the first MRR and the second MRR have the same resonant wavelength, causing a superlinear transmission region of the second MRR to align with a resonant wavelength of the first MRR.
9 . The coherent ONN of claim 8 , wherein the first output port and the second output port are formed on a same side of the first MRR and the second MRR thereby reducing routing complexities.
10 . The coherent ONN of claim 8 , wherein the second MRR is over-coupled to the second bus waveguide resulting in a superlinear transmission region comprising superlinear phase variations near a resonant wavelength of the second MRR.
11 . The coherent ONN of claim 10 , further comprising a first phase shifter formed along one or both of the first bus waveguide or the second bus waveguide to induce a predetermined phase shift in a light propagating via the first bus waveguide and the second bus waveguide causing the superlinear transmission region of the second MRR to align with superlinear transmission region of the first MRR thereby improving linearity of the optical output signal.
12 . The coherent ONN of claim 8 , further comprising:
a second phase shifter formed along the first MRR to control a phase angle of light propagating inside the first MRR; and
a third phase shifter formed along the second MRR to control a phase angle of light propagating inside the second MRR.
13 . A wavelength division multiplexing (WDM) optical neural network (ONN) system, comprising:
a first bus waveguide;
a second bus waveguide; and
an optical distributor coupled to the first bus waveguide and the second bus waveguide and comprising two input ports and two output ports, wherein the optical distributor receives an input light through one of the two input ports, generates a first light stream and a second light stream from the input light, and feeds the first light stream to the first bus waveguide via a first output port of the two output ports and the second light stream to the second bus waveguide via a second output port of the two output ports,
a plurality of pairs of microring resonators (MRRs) formed between the first bus waveguide and the second bus waveguide along a length of the first bus waveguide and the second bus waveguide, wherein each of the plurality of pairs of MRRs comprises:
a first microring resonator (MRR) optically coupled to the first bus waveguide; and
a second MRR optically coupled to the second bus waveguide and the first MRR, wherein the first MRR is formed between the first bus waveguide and the second MRR, and the second MRR is formed between the first MRR and the second bus waveguide;
wherein the first MRR and the second MRR are designed to have equal diameters, thicknesses, and widths so that the first MRR and the second MRR have the same resonant wavelength, causing a superlinear transmission region of the second MRR to align with a resonant wavelength of the first MRR.
14 . The WDM ONN of claim 13 , wherein the second MRR is over-coupled to the second bus waveguide resulting in a superlinear transmission region comprising superlinear phase variations near a resonant wavelength of the second MRR.
15 . The WDM ONN of claim 13 , further comprising a phase shifter formed along one or both of the first MRR or second MRR to control a phase angle of light propagating inside the first MRR or the second MRR to align a superlinear transmission region of the second MRR with a resonant wavelength of the first MRR thereby improving linearity of an optical output signal of the WDM ONN.