Wavelength-division multiplexed polarization-insensitive transmissive modulator

1. A wavelength-division multiplexed (WDM) polarization insensitive transmissive-type modulator (PITM) comprising:

a first polarization splitter-rotator (PSR);

a first demultiplexor coupled to the first PSR;

a second demultiplexor coupled to the first PSR;

a plurality of multi-port modulators, each multi-port modulator being coupled to the first demultiplexor and the second demultiplexor and comprising a first output port configured to transmit a first single-wavelength modulated signal, the first single-wavelength modulated signal comprising a modulated first single-wavelength continuous wavelength (CW) light beam, and a second output port configured to transmit a second single-wavelength modulated signal, the second single-wavelength modulated signal comprising a modulated second single-wavelength CW light beam;

a first multiplexor coupled to the plurality of multi-port modulators;

a second multiplexor coupled to the plurality of multi-port modulators; and

a second PSR coupled to the first multiplexor and with the second multiplexor, the second PSR configured to output a multi-wavelength modulated signal that includes the first single-wavelength modulated signal and the second single-wavelength modulated signal of each of the multi-port modulators.

2. The WDM PITM of claim 1 :

wherein the first PSR is configured to:

receive, at a first PSR input port, a multi-wavelength CW light beam;

split the multi-wavelength CW light beam into a first multi-wavelength CW light beam and a second multi-wavelength CW light beam, wherein the first multi-wavelength CW light beam has a transverse electric (TE) polarization orientation and travels in a clockwise direction, and wherein the second multi-wavelength CW light beam has a transverse magnetic (TM) polarization orientation and travels in a counter-clockwise direction;

rotate the second multi-wavelength CW light beam by 90 degrees, such that the second multi-wavelength CW light beam exhibits TE polarization;

transmit, from a first PSR output port, the first multi-wavelength CW light beam; and

transmit, from a second PSR output port, the second multi-wavelength CW light beam.

3. The WDM PITM of claim 1 :

wherein the first demultiplexor comprises:

a first demultiplexor input port; and

a plurality of first demultiplexor output ports,

wherein the first demultiplexor is configured to:

receive, at the first demultiplexor input port, a first multi-wavelength CW light beam; and

transmit, from the plurality of first demultiplexor output ports, a plurality of single-wavelength CW light beams, wherein one single-wavelength CW light beam is transmitted from each one of the plurality of first demultiplexor output ports,

wherein the second demultiplexor comprises:

a second demultiplexor input port; and

a plurality of second demultiplexor output ports, and

wherein the second demultiplexor is configured to:

receive, at the second demultiplexor input port, a second multi-wavelength CW light beam; and

transmit, from the plurality of second demultiplexor output ports, a plurality of single-wavelength CW light beams, wherein one single-wavelength CW light beam is transmitted from each one of the plurality of second demultiplexor output ports.

4. The WDM PITM of claim 1 :

wherein each multi-port modulator is configured to:

receive, at a first multi-port modulator input port, a first single-wavelength CW light beam from the first demultiplexor;

receive, at a second multi-port modulator input port, a second single-wavelength CW light beam from the second demultiplexor;

modulate the received first single-wavelength CW light beam to produce the first single-wavelength modulated signal;

modulate the received second single-wavelength CW light beam to produce the second single-wavelength modulated signal;

transmit, from the first output port, the first single-wavelength modulated signal; and

transmit, from the second output port, the second single-wavelength modulated signal.

5. The WDM PITM of claim 4 , wherein each multi-port modulator comprises a Mach-Zehnder modulator (MZM).

6. The WDM PITM of claim 5 wherein each MZM further comprises:

a first optical coupler coupling the first single-wavelength CW light beam and the second single-wavelength modulated signal;

a second optical coupler coupling the second single-wavelength CW light beam and the first single-wavelength modulated signal;

a first tap coupling out a first portion of the first single-wavelength modulated signal to send to a monitor photodetector (mPD);

a second tap coupling out a second portion of the second single-wavelength modulated signal to send to the mPD, wherein the mPD is configured to generate a combined photodetector (PD) current; and

a processor coupled to the mPD and configured to:

generate a bias current according to the combined PD current; and

apply the bias current to a phase shifter on an arm of the MZM to control the MZM.

7. The WDM PITM of claim 4 , wherein each multi-port modulator comprises an in-phase/quadrature phase modulator (IQM).

8. The WDM PITM of claim 7 wherein each IQM further comprises:

a first optical coupler coupling the first single-wavelength CW light beam and the second single-wavelength modulated signal;

a second optical coupler coupling the second single-wavelength CW light beam and the first single-wavelength modulated signal;

a first tap coupling out a first portion of the first single-wavelength modulated signal to send to a monitor photodetector (mPD);

a second tap coupling out a second portion of the second single-wavelength modulated signal to send to the mPD, wherein the mPD is configured to generate a combined photodetector (PD) current; and

a processor coupled to the mPD and configured to:

generate three bias currents based on the combined PD current; and

apply the three bias currents to a first phase shifter on an in-phase channel of the IQM, a second phase shifter on a quadrature-phase channel of the IQM, and a third phase shifter on a parent channel of the IQM, to control the IQM.

9. The WDM PITM of claim 4 , wherein each multi-port modulator comprises a micro-ring (MR) resonator.

10. The WDM PITM of claim 1 :

wherein the first multiplexor is configured to:

receive, at each of a plurality of first multiplexor input ports, a first single-wavelength modulated signal from one of the plurality of multi-port modulators; and

transmit, from a first multiplexor output port, a first multi-wavelength modulated signal;

wherein the second multiplexor is configured to:

receive, at each of a plurality of second multiplexor input ports, a second single-wavelength modulated signal from one of the plurality of multi-port modulators; and

transmit, from a second multiplexor output port, a second multi-wavelength modulated signal.

11. The WDM PITM of claim 1 :

wherein the second PSR is configured to:

receive, at a second PSR input port, a first multi-wavelength modulated signal;

receive, at a first PSR input port, a second multi-wavelength modulated signal;

rotate the first or second multi-wavelength modulated signal by 90 degrees;

combine the first multi-wavelength modulated signal and the second multi-wavelength modulated signal to produce the multi-wavelength modulated signal; and

transmit, from a PSR output port, the multi-wavelength modulated signal.

12. The WDM PITM of claim 1 wherein the first demultiplexor, the second demultiplexor, the first multiplexor, and the second multiplexor are arrayed waveguide gratings or micro ring resonators.

13. A method of modulating a multi-wavelength continuous wave (CW) light beam using a wavelength-division multiplexed (WDM) polarization insensitive transmissive-type modulator (PITM), the method comprising:

splitting, by a first polarization splitter-rotator (PSR) of the WDM PITM, a multi-wavelength CW light beam into a first multi-wavelength CW light beam and a second multi-wavelength CW light beam;

splitting, by a first demultiplexor of the WDM PITM, the first multi-wavelength CW light beam into a first plurality of single-wavelength CW light beams;

splitting, by a second demultiplexor of the WDM PITM, the second multi-wavelength CW light beam into a second plurality of single-wavelength CW light beams;

modulating, by a plurality of multi-port modulators of the WDM PITM, the first plurality of single-wavelength CW light beams and the second plurality of single-wavelength CW light beams into a first plurality of single-wavelength modulated signals and a second plurality of single-wavelength modulated signals;

combining, by a first multiplexor of the WDM PITM, the first plurality of single-wavelength modulated signals into a first multi-wavelength modulated signal;

combining, by a second multiplexor of the WDM PITM, the second plurality of single-wavelength modulated signals into a second multi-wavelength modulated signal;

combining, by a second PSR of the WDM PITM, the first multi-wavelength modulated signal and the second multi-wavelength modulated signal into a multi-wavelength modulated signal; and

outputting, from the second PSR of the WDM PITM, the multi-wavelength modulated signal including the first plurality of single-wavelength modulated signals and the second plurality of single-wavelength modulated signals.

14. The method of claim 13 , wherein the first multi-wavelength CW light beam has a transverse electric polarization orientation and travels in a clockwise direction, wherein the second multi-wavelength CW light beam has a transverse magnetic polarization orientation and travels in a counter-clockwise direction, wherein after the first PSR splits the multi-wavelength CW light beam into the first multi-wavelength CW light beam and the second multi-wavelength CW light beam, the first PSR rotates the second multi-wavelength CW light beam by 90 degrees.

15. The method of claim 13 , wherein splitting the multi-wavelength CW light beam comprises:

receiving, at an input port of the first PSR, the multi-wavelength CW light beam;

splitting the multi-wavelength CW light beam into a first multi-wavelength CW light beam and a second multi-wavelength CW light beam, wherein the first multi-wavelength CW light beam has a transverse electric polarization orientation and travels in a clockwise direction, and wherein the second multi-wavelength CW light beam has a transverse magnetic polarization orientation and travels in a counter-clockwise direction;

rotating the second multi-wavelength CW light beam by 90 degrees;

transmitting, from a first output port of the first PSR, the first multi-wavelength CW light beam; and

transmitting, from a second output port of the first PSR, the second multi-wavelength CW light beam.

16. The method of claim 13 , wherein modulating the first plurality of single-wavelength CW light beams and the second plurality of single-wavelength CW light beams comprises, for each multi-port modulator:

receiving, at a first input port, one single-wavelength CW light beam of the first plurality of single-wavelength CW light beams and modulating the received single-wavelength CW light beam to produce a first single-wavelength modulated signal;

receiving, at a second input port, one single-wavelength CW light beam of the second plurality of single-wavelength CW light beams and modulating the received single-wavelength CW light beam to produce a second single-wavelength polarized signal;

transmitting, from a first output port, the first single-wavelength modulated signal; and

transmitting, from a second output port, the second single-wavelength polarized signal.

17. The method of claim 13 , wherein each multi-port modulator FPM of the plurality of multi-port modulators comprises a cross-state modulator.

18. The method of claim 13 , wherein each multi-port modulator FPM of the plurality of multi-port modulators comprises a bypass-state modulator.

19. The method of claim 13 ,

wherein combining the first plurality of single-wavelength modulated signals into the first multi-wavelength modulated signal comprises:

receiving, at a plurality of input ports of the first multiplexor, the first plurality of single-wavelength modulated signals;

combining the first plurality of single-wavelength modulated signals into the first multi-wavelength modulated signal; and

transmitting, from an output port of the first multiplexor, the first multi-wavelength modulated signal, and

wherein combining the second plurality of single-wavelength modulated signals into a second multi-wavelength polarized signal comprises:

receiving, at a plurality of input ports of the first multiplexor, the second plurality of single-wavelength modulated signals;

combining the second plurality of single-wavelength modulated signals into the second multi-wavelength modulated signal; and

transmitting, from an output port of the second multiplexor, the second multi-wavelength modulated signal.

20. An wavelength-division multiplexed (WDM) polarization insensitive transmissive-type modulator (PITM) comprising:

an input port configured to receive a multi-wavelength continuous wave (CW) light beam;

an output port configured to transmit a multi-wavelength modulated signal; and

a plurality of multi-port modulators coupled to the input port and the output port, wherein each multi-port modulator comprises:

a first input port configured to receive a first single-wavelength CW light beam, wherein the first single-wavelength CW light beam has been extracted from the multi-wavelength CW light beam, wherein the first single-wavelength CW light beam has a transverse electric polarization orientation, and wherein the first single-wavelength CW light beam travels in a clockwise direction;

a second input port configured to receive a second single-wavelength CW light beam, wherein the second single-wavelength CW light beam has been extracted from the multi-wavelength CW light beam, wherein the second single-wavelength CW light beam has a transverse magnetic polarization orientation that has been rotated 90 degrees, and wherein the second single-wavelength CW light beam travels in a counter-clockwise direction;

a first output port configured to transmit a first single-wavelength modulated signal, wherein the first single-wavelength modulated signal comprising the first single-wavelength CW light beam; and

a second output port configured to transmit a second single-wavelength modulated signal, wherein the second single-wavelength modulated signal comprising the second single-wavelength CW light beam, wherein the multi-wavelength modulated signal comprises the first single-wavelength modulated signal and the second single-wavelength modulated signal of each of the multi-port modulators.

21. The WDM PITM of claim 1 , wherein the multi-port modulator comprises a four-port modulator (FPM).

22. The method of claim 13 , wherein the multi-port modulator comprises a four-port modulator (FPM).

23. The WDM PITM of claim 20 , wherein the multi-port modulator comprises a four-port modulator (FPM).