Granted Patent B2

US 8,249,467 · App. 12/721,802 · Granted Aug 21, 2012

Abstract

Claims (42)

1. A method of testing a dual-polarization optical transmitter comprising a pair of polarization transmitters for respectively generating first and second polarization signals, and a combiner for generating an optical signal composed of the first and second polarization signals with respective different polarization vectors, the method comprising:

controlling each of the polarization transmitters to transmit respective polarization optical signals having predetermined characteristics;

tapping an output of the dual-polarization optical transmitter to obtain a first tap signal representative of the first polarization signal, and a second tap signal representative of the second polarization signal;

combining the first and second tap signals to generate a combined light wherein at least a component of the first tap signal and a component of the second tap signal are co-polarized; and

detecting a power level of the combined light.

2. The method as claimed in claim 1 , wherein tapping an output of the dual-polarization optical transmitter comprises tapping the optical signal transmitted by the dual-polarization optical transmitter to obtain a dual polarization tap light including the first and second tap signal.

3. The method as claimed in claim 2 , wherein combining the first and second tap signals comprises:

polarization splitting the dual polarization tap light to separate the first and second tap signals;

adjusting a polarization angle of at least one of the first and second tap signals, such that at least a component of the first tap signal and a component of the second tap signal are co-polarized; and

combining at least the co-polarized components of the first and second tap signals.

4. The method as claimed in claim 3 , wherein adjusting the polarization angle comprising rotating the polarization vector of at least one of the tap signals such that the first and second tap signals are co-polarized.

5. The method as claimed in claim 2 , wherein combining the first and second tap signals comprises supplying the dual polarization tap light to a polarization beam splitter such that respective polarization vectors of the first ad second tap signals are oriented at an equal angle with respect to a principle axis of the polarization beam splitter.

6. The method as claimed in claim 1 , wherein tapping an output of the dual-polarization optical transmitter comprises tapping a complementary output of each polarization transmitter to obtain the first and second tap signals.

7. The method as claimed in claim 6 , wherein combining the first and second tap signals comprises:

adjusting a polarization angle of at least one of the first and second tap signals, such that at least a component of the first tap signal and a component of the second tap signal are co-polarized; and

combining at least the co-polarized components of the first and second tap signals.

8. The method as claimed in claim 1 , further comprising processing the detected power to calculate a value of a selected performance parameter of the dual-polarization optical transmitter.

9. The method as claimed in claim 1 , further comprising comparing a detected feature to a predetermined threshold value.

10. The method as claimed in claim 9 , wherein the predetermined threshold value is based on a tolerance of selected performance parameter of the dual-polarization optical transmitter.

11. A system for testing a dual-polarization optical transmitter comprising a pair of polarization transmitters for respectively generating first and second polarization signals, and a combiner for generating an optical signal composed of the first and second polarization signals with respective different polarization vectors, the system comprising:

a processor for controlling each of the polarization transmitters to transmit respective polarization optical signals having predetermined characteristics;

means for tapping an output of the dual-polarization optical transmitter to obtain a first tap signal representative of the first polarization signal, and a second tap signal representative of the second polarization signal;

means for combining the first and second tap signals to generate a combined light wherein at least a component of the first tap signal and a component of the second tap signal are co-polarized; and

a photodetector for detecting a power level of the combined light.

12. The system as claimed in claim 11 , wherein the means for tapping an output of the dual-polarization optical transmitter comprises an optical tap connected to tap the optical signal transmitted by the dual-polarization optical transmitter to obtain a corresponding dual polarization tap light including the first and second tap signal.

13. The system as claimed in claim 12 , wherein the means for combining the first and second tap signals comprises:

a polarization beam splitter configured to split the dual polarization tap light to separate the first and second tap signals;

a polarization rotator for adjusting a polarization angle of at least one of the first and second tap signals, such that at least a component of the first tap signal and a component of the second tap signal are co-polarized; and

an optical combiner for combining at least co-polarized components of the first and second tap signals.

14. The system as claimed in claim 13 , wherein the polarization rotator is configured to rotate the polarization vector of at least one of the tap signals such that the first and second tap signals are co-polarized.

15. The system as claimed in claim 12 , wherein the means for combining the first and second tap signals comprises an optical connection for supplying the dual polarization tap light to a polarization beam splitter such that respective polarization vectors of the first ad second tap signals are oriented at an equal angle with respect to a principle axis of the polarization beam splitter.

16. The system as claimed in claim 15 , wherein the optical connection comprises a polarization rotator.

17. The system as claimed in claim 11 , wherein the means for tapping an output of the dual-polarization optical transmitter comprises a complementary output port of each polarization transmitter.

18. The system as claimed in claim 17 , wherein the means for combining the first and second tap signals comprises:

a polarization rotator for adjusting a polarization angle of at least one of the first and second tap signals, such that at least a component of the first tap signal and a component of the second tap signal are co-polarized; and

an optical combiner for combining at least co-polarized components of the first and second tap signals.

19. The system as claimed in claim 11 , wherein a polarization rotator is responsive to a control signal from the processor.

20. The system as claimed in claim 11 , wherein the processor is further configured to process the detected power level to calculate a value of a selected performance parameter of the dual-polarization optical transmitter.

21. The system as claimed in claim 11 , wherein the processor is further configured to compare the detected power level to a predetermined threshold value.

22. The system as claimed in claim 21 , wherein the predetermined threshold value is based on a tolerance of a selected performance parameter of the dual-polarization optical transmitter.

23. The system as claimed in claim 11 , wherein the processor comprises an interface for signalling between the system and a computer.

24. The system as claimed in claim 11 where the system is co-packaged with the dual-polarization transmitter.

Assignments (8)