Polarization diversified wavelength domain demultiplexer with a single set of outputs

1. A system comprising:

a polarization beam splitter configured to output a first polarized signal and a second polarized signal based on an input signal; and

a wavelength demultiplexer (WDM) that is polarization diversified,

the WDM comprising

a first star coupler having a first input and a second input,

a second star coupler having a set of output waveguides, and

arrayed waveguide grating (AWG), wherein the AWG has a shape configured to align a first transmission spectra of the first polarized signal and a second transmission spectra of the second polarization signal from the polarization beam splitter such that the WDM output signals are directed to a single set of output waveguides,

wherein the WDM is configured to receive as two inputs, the first polarized signal and the second polarization signal from the polarization beam splitter, wherein the WDM is further configured to output signals to the single set of output waveguides,

wherein each output waveguide of the single set is configured to recombine signals from both the first polarized signal and the second polarized signal.

2. The system of claim 1 , wherein the WDM is part of a photonic integrated circuit.

3. The system of claim 2 , wherein the outputs of the WDM are integrated waveguides.

4. The system of claim 1 , wherein the shape is configured to direct a plurality of signals output from the first star coupler to specific output locations at the second star coupler.

5. A system comprising:

an optical receiver, comprising:

a polarization beam splitter configured to output a first polarized signal having a first transmission spectra and a second polarized signal having a second transmission spectra based on an input signal; and

a wavelength demultiplexer (WDM) having two inputs, a first input and a second input, that are connected to the two outputs of the polarization beam splitter, and configured to align the first transmission spectra the second transmission spectra and output a single set of outputs that carry signals of both polarizations, based on the first polarized signal from the first input and the second polarized signal from the second input.

6. The system of claim 5 , wherein the WDM is part of a photonic integrated circuit.

7. The system of claim 5 , wherein the WDM is an arrayed waveguide grating.

8. The system of claim 5 , wherein the WDM is an echelle grating.

9. The system of claim 6 , wherein the outputs of the WDM are integrated waveguides.

10. A method of demultiplexing signals, the method comprising:

receiving an input signal;

splitting polarizations, via a polarization beam splitter, of the input signal into a first polarization signal having a first transmission spectra and a second polarization signal having a second transmission spectra;

coupling the first polarization signal to a wavelength demultiplexer via a first input and the second polarization signal to the same wavelength demultiplexer via a second input;

separating the wavelengths using a first star coupler of the wavelength demultiplexer;

aligning the first transmission spectra and the second transmission spectra, using a second star coupler of the wavelength demultiplexer; and

outputting different signals to one set of outputs that carry signals of both polarizations from the second star coupler.

11. The method of claim 10 , wherein the wavelength demultiplexer is an arrayed waveguide grating.

12. The method of claim 10 , wherein the wavelength demultiplexer is an echelle grating.

13. The method of claim 10 , wherein the wavelength demultiplexer comprises one or more integrated waveguides.