Reduced crosstalk photonic switch
Described are various configurations of reduced crosstalk optical switches. Various embodiments can reduce or entirely eliminate crosstalk using a coupler that has a power-splitting ratio that compensates for amplitude imbalance caused by phase modulator attenuation. Some embodiments implement a plurality of phase modulators and couplers as part of a dilated switch network to increase overall bandwidth and further reduce potential for crosstalk.
1. A method of routing light in a switch network, the method comprising:
receiving, by multiple phase modulators, multiple beam components of a light beam;
generating, using one of the multiple phase modulators, a phase-shifted beam component by phase-shifting one of the multiple beam components of the light beam such that the phase-shifted beam component is out of phase with at least one other beam component from the multiple beam components of the light beam, the phase-shifted beam component exhibiting attenuation caused by the one of the multiple phase modulators; and
combining, using an optical coupler, the phase-shifted beam component with the at least one other beam component such that constructive interference occurs for a first output port of the optical coupler and destructive interference occurs for a second output port of the optical coupler, the optical coupler having a physical shape that compensates for the attenuation caused by the one of the multiple phase modulators.
2. The method of claim 1 , wherein the multiple phase modulators are silicon-based modulators that phase-shift the one of the multiple beam components based on a quantity of embedded positive and negative carriers.
3. The method of claim 1 , wherein the multiple phase modulators include a first phase modulator and a second phase modulator, wherein the phase-shifted beam component is phase-shifted by the first phase modulator, and wherein the second phase modulator is in an off-state that passes the at least one other beam component un-shifted.
4. The method of claim 3 , wherein generating the phase-shifted beam component comprises shifting, using the first phase modulator, the phase of the one of the multiple beam components by approximately 90 degrees.
5. The method of claim 3 , wherein generating the phase-shifted beam component comprises shifting, using the first phase modulator, the phase of the one of the multiple beam components by approximately 180 degrees.
6. The method of claim 1 , wherein the optical coupler has a power splitting ratio that compensates for attenuation in the modulated beam component.
7. The method of claim 6 , wherein the power splitting ratio is one of: t^2/(1+t^2), where t is a ratio of field transmission coefficients of the multiple phase modulators.
8. The method of claim 6 , wherein the power splitting ratio is t/(1+t), where t is a ratio of field transmission coefficients of the multiple phase modulators.
9. The method of claim 1 , wherein the optical coupler has tapered sides that modify a superposition of light in the optical coupler such that a power splitting ratio of the optical coupler compensates for attenuation in the modulated beam component.
10. The method of claim 1 , wherein the light beam includes an individual data stream, and the multiple beam components of the optical signal include facsimiles of the data stream.
11. The method of claim 1 , further comprising:
receiving, using an additional optical coupler, the light beam;
generating, using the additional optical coupler, the multiple beam components by splitting the light beam such that the multiple beam components have equal power; and
outputting, using the additional optical coupler, the multiple beam components to the multiple phase modulators.
12. An optical device for routing signals in a switch network, the optical device comprising:
a plurality of phase modulators receiving multiple beam components, one of the plurality of phase modulators generating a phase-shifted beam component by phase-shifting one of the multiple beam components such that the phase-shifted beam component is out of phase with at least one other beam component in the multiple beam components, the phase-shifted beam component exhibiting attenuation caused by the one of the plurality of phase modulators; and
an optical coupler to combine the phase-shifted beam component with the at least one other beam component such that constructive interference occurs for a first output port of the optical coupler and destructive interference occurs for a second output port of the optical coupler, the optical coupler having a physical shape that compensates for the attenuation caused by the one of the plurality of phase modulators.
13. The optical device of claim 12 , wherein the plurality of phase modulators are silicon-based modulators that modulate based on a quantity of embedded positive and negative carriers.
14. The optical device of claim 12 , wherein the plurality of phase modulators include a first phase modulator and a second phase modulator, wherein the phase-shifted beam component is phase-shifted by the first phase modulator, and wherein the second phase modulator is an off-state that passes the at least one other beam component un-shifted.
15. The optical device of claim 12 , wherein the optical coupler has a power splitting ratio that compensates for attenuation in the modulated beam component, wherein the power splitting ratio is t^2/(1+t^2), where t is field transmission.
16. The optical device of claim 12 , wherein the optical coupler has tapered sides that modify a superposition of light in the optical coupler such that a power splitting ratio of the optical coupler compensates for attenuation in the phase-shifted beam component.