Integrated optical network unit

1. An optical network unit comprising:

a transmit/receive port, wherein the transmit/receive port is configured to be coupled to an optical fiber;

a silicon waveguide optically coupled to the transmit/receive port, wherein the silicon waveguide is not the same as the optical fiber;

a tunable filter coupled to the silicon waveguide and providing a first output for a first frequency band and a second output for a second frequency band;

a polarization diverse receiver coupled to the tunable filter, wherein the polarization diverse receiver includes:

a polarization splitter coupled to the first output and providing a first polarization output and a second polarization output;

a first band pass filter coupled to the first polarization output;

a polarization rotator coupled to the second polarization output;

a second band pass filter coupled to the polarization rotator; and

a detector coupled to the first band pass filter and the second band pass filter; and

a laser coupled to the tunable filter.

2. The optical network unit of claim 1 , wherein:

the first band pass filter is for the L band; and

the second band pass filter is for the L band.

3. The optical network unit of claim 1 wherein the detector comprises a material coupled to a silicon structure.

4. The optical network unit of claim 1 wherein the detector comprises a germanium material coupled to a silicon structure.

5. The optical network unit of claim 1 wherein the laser comprises a tunable laser.

6. The optical network unit of claim 1 further comprising an optical modulator disposed between the laser and the tunable filter.

7. The optical network unit of claim 1 wherein the tunable filter passes C-band signals from the silicon waveguide to the first output in a downstream path and passes L-band signals from the second output to the silicon waveguide in an upstream path.

8. The optical network unit of claim 1 further comprising a C-band band pass filter coupled to the second output of the tunable filter.

9. The optical network unit of claim 1 wherein the laser comprises a III-V material coupled to a silicon reflector structure.

10. A method of operating a transceiver, the method comprising:

receiving, at a Tx/Rx port, a downstream optical signal comprising data in multiple wavelength bands including a first band, wherein the downstream optical signal is received from an optical fiber coupled to the Tx/Rx port;

passing the downstream optical signal from the Tx/Rx port through a silicon waveguide and through a tunable filter;

detecting the downstream optical signal at a polarization diverse receiver after passing the downstream optical signal through the silicon waveguide and the tunable filter, wherein the polarization diverse receiver includes:

a polarization splitter having a TE output and a TM output;

a polarization rotator operable to receive the TM output and generate a TE′ output;

a first band pass filter coupled to the TE output;

a second band pass filter coupled to the polarization rotator; and

a detector coupled to the first band pass filter and the second band pass filter;

generating an upstream optical signal in a second band;

transmitting the upstream optical signal through the tunable filter; and

outputting the upstream optical signal from the Tx/Rx port.

11. The method of claim 10 further comprising filtering the downstream optical signal after passing through the tunable filter and before detecting the downstream optical signal.

12. The method of claim 10 wherein the first band pass filter and the second band pass filter are operable to pass signals in the first band.

13. The method of claim 10 wherein generating the upstream optical signal comprises:

producing a laser signal using a tunable laser; and

modulating the laser signal to generate the upstream optical signal.

14. The method of claim 10 wherein the first band is the L band.

15. The method of claim 10 further comprising filtering the upstream optical signal using a band pass filter for the second band.

16. The method of claim 15 wherein the second band is the C band.