Optical demultiplexer and method of controlling an optical demultiplexer
An optical demultiplexer includes an interleaver with at least four ports including a first port adapted to receive the sum of two optical signals A and B, a second port and a third port respectively for signals A and B, and a fourth port. The optical demultiplexer further includes an optical component coupled to at least one of the two ports for signals A and B and configured to split the optical signal to be outputted into a weak intensity optical signal and a strong intensity optical signal.
1. An optical demultiplexer comprising:
a Mach-Zehnder interleaver having a first port configured to receive an input of a sum of a first optical signal with a second optical signal, a second port configured to output the first optical signal, a third port configured to output the second optical signal, and a fourth port; and
an optical component coupled to the second port and configured to split the first optical signal into a weak intensity optical signal and a strong intensity optical signal;
said optical component configured to generate the weak intensity optical signal and back reflect it through said Mach-Zehnder interleaver towards the fourth port.
2. The optical demultiplexer of claim 1 , further comprising:
an optical device configured to receive an input of said weak intensity optical signal and to generate at least a feedback optical signal;
a sensor configured to receive an input of said feedback optical signal and to generate a corresponding electric error signal;
an actuator controlled by a control signal and configured to adjust an optical path difference of said Mach-Zehnder interleaver; and
a control block configured to receive said electric error signal and to generate said control signal to reduce the feedback optical signal.
3. The optical demultiplexer of claim 2 , wherein said sensor comprises a photo-detector coupled to said fourth port of said Mach-Zehnder interleaver and configured to receive an input of said feedback optical signal corresponding to a portion of said weak intensity optical signal.
4. The optical demultiplexer of claim 1 , wherein said optical component comprises a partially reflective grating.
5. The optical demultiplexer of claim 1 , wherein said optical component comprises a partially reflective Bragg grating.
6. An optical demultiplexer comprising:
a plurality of 1×2 optical demultiplexers coupled together according to a perfect binary tree architecture;
each optical demultiplexer of the plurality of 1×2 optical demultiplexers comprising:
a Mach-Zehnder interleaver having a first port configured to receive an input of a sum of a first optical signal with a second optical signal, a second port configured to output the first optical signal, a third port configured to output the second optical signal, and a fourth port; and
an optical component coupled to the second port and configured to split the first optical signal into a weak intensity optical signal and a strong intensity optical signal;
said optical component configured to generate the weak intensity optical signal and back reflect it through said Mach-Zehnder interleaver towards the fourth port.
7. The optical demultiplexer of claim 6 , further comprising:
an optical device configured to receive an input of said weak intensity optical signal and to generate at least a feedback optical signal; and
a sensor configured to receive an input of said feedback optical signal and to generate a corresponding electric error signal.
8. The optical demultiplexer of claim 7 , further comprising an actuator controlled by a control signal and configured to adjust an optical path difference of said Mach-Zehnder interleaver.
9. The optical demultiplexer of claim 8 , further comprising a control block configured to receive said electric error signal and to generate said control signal to reduce the feedback optical signal.
10. The optical demultiplexor of claim 7 , wherein said sensor comprises a photo-detector coupled to said fourth port of said Mach-Zehnder interleaver and configured to receive an input of said feedback optical signal corresponding to a portion of said weak intensity optical signal.
11. A method of controlling an optical demultiplexer comprising a Mach-Zehnder interleaver having a first port configured to receive an input of a sum of a first optical signal with a second optical signal, a second port configured to output the first optical signal, a third port configured to output the second optical signal, and a fourth port, the method comprising:
splitting the first optical signal into a weak intensity optical signal and a strong intensity optical signal;
generating a feedback optical signal from said weak intensity optical signal;
generating an electric error signal corresponding to said feedback optical signal;
adjusting an optical path difference of said Mach-Zehnder interleaver to reduce the electric error signal; and
back reflecting the weak intensity optical signal through said Mach-Zehnder interleaver towards the fourth port.
12. The method of claim 11 , further comprising using an optical component to generate the weak intensity optical signal and back reflect it through said Mach-Zehnder interleaver towards the fourth port.
13. The method of claim 12 , wherein the optical component comprises a reflective grating.
14. The method of claim 12 , wherein the optical component comprises a partially reflective Bragg grating.
15. An optical demultiplexer comprising:
a first Mach-Zehnder interleaver having a first port configured to receive an input of a sum of a first optical signal with a second optical signal, a second port configured to output the first optical signal, a third port configured to output the second optical signal, and a fourth port;
a tap directional coupler having an input port coupled to said first Mach-Zehnder interleaver to receive the first optical signal or the second optical signal, a main output port configured to deliver the strong intensity optical signal, and an auxiliary output port configured to deliver the weak intensity optical signal;
a second Mach-Zehnder interleaver identical to said first Mach-Zehnder interleaver and coupled in cascade thereto to receive an input at a corresponding first port of said weak intensity optical signal;
an optical device configured to receive an input of said weak intensity optical signal and to generate at least a feedback optical signal; and
photo-detectors coupled to the corresponding second and third ports of said second Mach-Zehnder interleaver and configured to generate respective electric error signals corresponding to portions of said weak intensity optical signal that travel through said second Mach-Zehnder interleaver from said first port to said second and third ports.
16. The optical demultiplexer of claim 15 , further comprising:
a sensor configured to receive an input of said feedback optical signal and to generate a corresponding electric error signal; and
a control block configured to receive said electric error signal and to generate a control signal to reduce the feedback optical signal.
17. The optical demultiplexer of claim 16 , wherein said second Mach-Zehnder interleaver having at least one actuator is configured to be controlled by said control block.
18. The optical demultiplexer of claim 17 , wherein said control block is configured to receive said electric error signals and to adjust optical path differences of said first Mach-Zehnder interleaver and said second Mach-Zehnder interleaver.
19. A method of controlling an optical demultiplexer comprising a first Mach-Zehnder interleaver having a first port configured to receive an input of a sum of a first optical signal with a second optical signal, a second port configured to output the first optical signal, a third port configured to output the second optical signal, and a fourth port, the method comprising:
using a tap directional coupler to split the first optical signal into a weak intensity optical signal and a strong intensity optical signal;
receiving an input of said weak intensity optical signal at a second Mach-Zehnder interleaver identical to said first Mach-Zehnder interleaver and coupled in cascade thereto;
generating a feedback optical signal from said weak intensity optical signal;
generating an electric error signal corresponding to said feedback optical signal; and
adjusting an optical path difference of said first and second Mach-Zehnder interleavers to reduce the electric error signal.
20. The method of claim 19 , wherein the tap directional coupler is coupled to the second port of the first Mach-Zehnder interleaver.