Dual-polarization rotationally-insensitive monostatic transceiver with dual cladding fiber
An apparatus includes multiple dual cladding waveguides each having a single-mode interior section that transports one of multiple outgoing optical signals and a multimode section at least partially surrounding the interior section that transports one of multiple incoming optical signals. Different outgoing signals have different polarizations, and different incoming signals have different polarizations. The apparatus also includes a polarization beamsplitter that combines the multiple outgoing signals to produce transmit optical signals and separates receive optical signals to produce the multiple incoming signals.
1. An apparatus comprising:
multiple dual cladding waveguides each comprising (i) a single-mode interior section configured to transport one of multiple outgoing optical signals and (ii) a multimode section that at least partially surrounds the interior section and that is configured to transport one of multiple incoming optical signals, wherein different outgoing optical signals have different polarizations and different incoming optical signals have different polarizations;
a feedback loop; and
a polarization beamsplitter configured to:
(i) combine the multiple outgoing optical signals to produce transmit optical signals;
(ii) separate receive optical signals to produce the multiple incoming optical signals;
(iii) isolate incorrectly-polarized light of at least one of the multiple outgoing optical signals; and
(iv) direct the incorrectly-polarized light to the feedback loop;
wherein the feedback loop is configured to remove power to the incorrectly-polarized light of the at least one of the multiple outgoing optical signals.
2. The apparatus of claim 1 , further comprising:
a waveplate configured to (i) convert the transmit optical signals into first free-space optical signals having right-hand circular polarization to be transmitted on a first wavelength and left-hand circular polarization to be transmitted on a second wavelength and (ii) convert second free-space optical signals having the left-hand circular polarization received on the first wavelength and the right-hand circular polarization received on the second wavelength into the receive optical signals having a linear polarization.
3. The apparatus of claim 2 , further comprising a transceiver;
wherein the transceiver comprises the dual cladding waveguides, the polarization beamsplitter, and the waveplate.
4. The apparatus of claim 1 , further comprising:
multiple optical modification devices (OMDs) optically positioned between the dual cladding waveguides and the polarization beamsplitter, each OMD comprising a Faraday rotator and an additional waveplate;
wherein each Faraday rotator and its associated additional waveplate are collectively configured to provide a relative polarization change between (i) light propagating in a first direction through the Faraday rotator and the additional waveplate and (ii) light propagating in a second direction opposite the first direction through the Faraday rotator and the additional waveplate.
5. The apparatus of claim 1 , wherein the dual cladding waveguides comprise dual cladding fibers.
6. The apparatus of claim 1 , further comprising:
polarization controllers configured to control the polarizations of the multiple outgoing optical signals;
wherein the feedback loop is configured to control the polarization controllers.
7. The apparatus of claim 6 , further comprising multiple waveguide stressers;
wherein the feedback loop comprises multiple detectors each configured to receive the incorrectly-polarized light in the at least one of the outgoing optical signals; and
wherein each waveguide stresser is configured, in response to a signal from one of the multiple detectors, to stress at least one of the dual cladding waveguides, or single mode core, in order to adjust a polarization angle of the at least one of the outgoing optical signals.
8. A system comprising:
at least two dual cladding waveguides, each dual cladding waveguide corresponding to a respective optical channel and comprising (i) a single-mode interior section configured to transport one of multiple outgoing optical signals and (ii) a multimode section that at least partially surrounds the interior section and that is configured to transport one of multiple incoming optical signals, wherein a first optical channel is associated with a first outgoing optical signal having a first polarization and a first incoming optical signal having the first polarization, and wherein a second optical channel is associated with a second outgoing optical signal having a second polarization and a second incoming optical signal having the second polarization;
a feedback loop; and
a polarization beamsplitter configured to:
(i) combine the first and second outgoing optical signals to produce transmit optical signals;
(ii) separate receive optical signals to produce the first and second incoming optical signals;
(iii) isolate incorrectly-polarized light of at least one of the multiple outgoing optical signals; and
(iv) direct the incorrectly-polarized light to the feedback loop;
wherein the feedback loop is configured to remove power to the incorrectly-polarized light of the at least one of the multiple outgoing optical signals.
9. The system of claim 8 , further comprising:
a waveplate configured to (i) convert the transmit optical signals into first free-space optical signals having right-hand circular polarization to be transmitted on a first wavelength and left-hand circular polarization to be transmitted on a second wavelength and (ii) convert second free-space optical signals having the left-hand circular polarization received on the first wavelength and the right-hand circular polarization received on the second wavelength into the receive optical signals.
10. The system of claim 8 , further comprising:
multiple optical modification devices (OMDs) optically positioned between the dual cladding waveguides and the polarization beamsplitter, each OMD comprising a Faraday rotator and an additional waveplate;
wherein each Faraday rotator and its associated additional waveplate are collectively configured to provide a relative polarization change between (i) light propagating in a first direction through the Faraday rotator and the additional waveplate and (ii) light propagating in a second direction opposite the first direction through the Faraday rotator and the additional waveplate.
11. The system of claim 8 , further comprising:
polarization controllers configured to control the polarizations of the multiple outgoing optical signals;
wherein the feedback loop is configured to control the polarization controllers.
12. The system of claim 11 , further comprising multiple waveguide stressers;
wherein the feedback loop comprises multiple detectors each configured to receive the incorrectly-polarized light in the at least one of the outgoing optical signals; and
wherein each waveguide stresser is configured, in response to a signal from one of the multiple detectors, to stress at least one of the dual cladding waveguides, or a single mode core, in order to adjust a polarization angle of the at least one of the outgoing optical signals.
13. A method comprising:
transporting, via at least two dual cladding waveguides, multiple outgoing optical signals and multiple incoming optical signals, wherein different outgoing optical signals have different polarizations and different incoming optical signals have different polarizations,
wherein each of the dual cladding waveguides comprises (i) a single-mode interior section that transports one of the outgoing optical signals and (ii) a multimode section that at least partially surrounds the interior section and that transports one of the incoming optical signals;
combining the outgoing optical signals to produce transmit optical signals;
separating receive optical signals to produce the incoming optical signals;
isolating incorrectly-polarized light of at least one of the multiple outgoing optical signals;
directing the incorrectly-polarized light to a feedback loop; and
removing, by the feedback loop, power to the incorrectly-polarized light of the at least one of the multiple outgoing optical signals.
14. The method of claim 13 , further comprising:
using a waveplate to:
convert the transmit optical signals into first free-space optical signals having right-hand circular polarization to be transmitted on a first wavelength and left-hand circular polarization to be transmitted on a second wavelength; and
convert second free-space optical signals having the left-hand circular polarization received on the first wavelength and the right-hand circular polarization received on the second wavelength into the receive optical signals having a linear polarization.
15. The method of claim 13 , further comprising:
propagating the incoming optical signals and the outgoing optical signals through optical modification devices (OMDs) optically positioned between the dual cladding waveguides and a polarization beamsplitter, each OMD comprising a Faraday rotator and an additional waveplate;
wherein each Faraday rotator and its associated additional waveplate collectively provide a relative polarization change between (i) light propagating in a first direction through the Faraday rotator and the additional waveplate and (ii) light propagating in a second direction opposite the first direction through the Faraday rotator and the additional waveplate.
16. The method of claim 13 , further comprising:
controlling, by polarization controllers, the polarizations of the multiple outgoing optical signals in response to signals from the feedback loop.
17. The method of claim 16 , wherein controlling the polarizations of the multiple outgoing optical signals comprises:
in response to at least one signal from one or more of multiple detectors in the feedback loop, stressing, by at least one of the polarization controllers, at least one of the dual cladding waveguides, or a single mode fiber, in order to adjust a polarization angle of the at least one of the outgoing optical signals.
18. The system of claim 9 , further comprising a transceiver;
wherein the transceiver comprises the dual cladding waveguides, the polarization beamsplitter, and the waveplate.
19. The system of claim 8 , wherein the dual cladding waveguides comprise dual cladding fibers.
20. The method of claim 13 , wherein the dual cladding waveguides comprise dual cladding fibers.