Method and system for a free space CWDM MUX/DEMUX for integration with a grating coupler based silicon photonics platform

1. A method for communication, the method comprising:

in an optical assembly coupled to a photonic chip, the optical assembly comprising a lens array on the photonic chip, a mirror, a transparent spacer, and a plurality of thin film filters:

receiving an input optical signal comprising a plurality of optical signals at different wavelengths;

communicating the plurality of optical signals through the transparent spacer;

passing a first of the plurality of optical signals through the first of the plurality of thin film filters while reflecting others of the plurality of optical signals back through the transparent spacer;

reflecting the others of the plurality of optical signals towards a second of the plurality of thin film filters via a reflective surface of the transparent spacer;

passing one of the others of the plurality of optical signals through the second of the plurality of thin film filters; and

reflecting the passed optical signals into the photonic chip using the mirror.

2. The method according to claim 1 , wherein each of the plurality of thin film filters is configured for one of the different wavelengths of the plurality of optical signals.

3. The method according to claim 1 , wherein the input optical signal is a coarse wavelength division multiplexed (CWDM) signal.

4. The method according to claim 1 , wherein the optical assembly comprises a second lens array on a surface of the photonic chip, a second mirror, a second transparent spacer, and a second plurality of thin film filters.

5. The method according to claim 4 , comprising receiving a second input optical signal comprising a second plurality of optical signals at different wavelengths at the second transparent spacer.

6. A system for communication, the system comprising:

an optical assembly coupled to a surface of a photonic chip, the optical assembly comprising a lens array on the surface of the photonic chip, a mirror, a transparent spacer, and a plurality of thin film filters, the optical assembly being operable to:

receive an input optical signal comprising a plurality of optical signals at different wavelengths;

communicating the plurality of optical signals through the transparent spacer;

pass a first of the plurality of optical signals through the first of the plurality of thin film filters while reflecting others of the plurality of optical signals back through the transparent spacer;

reflect the others of the plurality of optical signals towards a second of the plurality of thin film filters via a reflective surface of the transparent spacer;

pass one of the others of the plurality of optical signals through the second of the plurality of thin film filters; and

reflect the passed optical signals into the photonic chip using the mirror.

7. The system according to claim 6 , wherein each of the plurality of thin film filters is configured for one of the different wavelengths of the plurality of optical signals.

8. The system according to claim 6 , wherein the input optical signal is a coarse wavelength division multiplexed (CWDM) signal.

9. The system according to claim 6 , wherein the optical assembly comprises a second lens array on the surface of the photonic chip, a second mirror, a second transparent spacer, and a second plurality of thin film filters.

10. The system according to claim 9 , wherein the optical assembly is operable to receive a second input optical signal comprising a second plurality of optical signals at different wavelengths at the second transparent spacer.

11. A method for communication, the method comprising:

in an optical assembly coupled to a surface of a photonic chip, the optical assembly comprising a lens array on the surface of the photonic chip, a mirror, first and second transparent spacers, and a plurality of thin film filters:

receiving a plurality of optical signals at different wavelengths in the optical assembly from the photonic chip via the lens array;

reflecting the plurality of optical signals into the first transparent spacer using the mirror;

passing at least a first and a second of the plurality of optical signals through a corresponding first and second thin film filter of the plurality of thin film filters into the second transparent spacer;

passing a third of the plurality of optical signals through the first transparent spacer into the second transparent spacer without passing through a thin film filter;

reflecting the second of the plurality of optical signals onto the first thin film filter via a reflective surface of the first transparent spacer;

successively reflecting the third of the plurality of optical signals between the reflective surface and the plurality of thin film filters until it reflects off of the first thin film filter; and

coupling the plurality of optical signals into an output waveguide.

12. The method according to claim 11 , comprising focusing the optical signals into the output waveguide using a silicon lens.

13. The method according to claim 11 , wherein each of the plurality of thin film filters is configured for one of the different wavelengths of the plurality of optical signals.

14. The method according to claim 11 , wherein the coupling of the plurality of optical signals into the output waveguide generates a coarse wavelength division multiplexed (CWDM) signal.

15. The method according to claim 11 , wherein the optical assembly comprises a second lens array on the surface of the photonic chip, a second mirror, a third transparent spacer, and a second plurality of thin film filters.

16. The method according to claim 15 , comprising receiving a second plurality of optical signals at different wavelengths via the second lens array and reflecting them using the second mirror to the second plurality of thin film filters via the third transparent spacer.

17. A system for communication, the system comprising:

an optical assembly coupled to a surface of a photonic chip, the optical assembly comprising a lens array on the surface of the photonic chip, a mirror, first and second transparent spacers, and a plurality of thin film filters, the optical assembly being operable to:

receive a plurality of optical signals at different wavelengths in the optical assembly from the photonic chip via the lens array;

reflect the plurality of optical signals into the first transparent spacer using the mirror;

pass at least a first and a second of the plurality of optical signals through a corresponding first and second thin film filter of the plurality of thin film filters into the second transparent spacer;

pass a third of the plurality of optical signals through the first transparent spacer into the second transparent spacer without passing through a thin film filter;

reflect the second of the plurality of optical signals onto the first thin film filter via a reflective surface of the first transparent spacer;

successively reflect the third of the plurality of optical signals between the reflective surface and the plurality of thin film filters until it reflects off of the first thin film filter; and

couple the plurality of optical signals into an output waveguide.

18. The system according to claim 17 , wherein the optical assembly is operable to focus the optical signals into the output waveguide using a silicon lens.

19. The system according to claim 17 , wherein each of the thin film filters is configured for one of the different wavelengths of the plurality of optical signals.

20. The system according to claim 17 , wherein coupling of the plurality of optical signals into the output waveguide generates a coarse wavelength division multiplexed (CWDM) signal.

21. The system according to claim 17 , wherein the optical assembly comprises a second lens array on the surface of the photonic chip, a second mirror, a third transparent spacer, and a second plurality of thin film filters.

22. The system according to claim 21 , wherein the optical assembly is operable to receive a second plurality of optical signals at different wavelengths via the second lens array and reflect them using the second mirror to the second plurality of thin film filters via the third transparent spacer.

23. A method for communication, the method comprising:

in an optical assembly coupled to a surface of a photonic chip, the optical assembly comprising a lens array on the surface of the photonic chip, a mirror, a transparent spacer, a plurality of thin film filters, a second lens array on the surface of the photonic chip, a second mirror, and a second plurality of thin film filters:

receiving an input optical signal comprising a plurality of optical signals at different wavelengths;

communicating the plurality of optical signals through the transparent spacer;

passing a first of the plurality of optical signals through a corresponding one of the plurality of thin film filters while reflecting others of the plurality of optical signals back into the transparent spacer;

reflecting the others of the plurality of optical signals towards a second of the plurality of thin film filters via a reflective surface of the transparent spacer;

passing one of the others of the plurality of optical signals through the second of the plurality of thin film filters; and

reflecting the passed optical signals into the photonic chip using the mirror.

24. The method according to claim 23 , wherein each of the plurality of thin film filters is configured for one of the different wavelengths of the plurality of optical signals.

25. The method according to claim 23 , wherein the input optical signal is a coarse wavelength division multiplexed (CWDM) signal.

26. The method according to claim 23 , comprising receiving a second input optical signal comprising a second plurality of optical signals at different wavelengths at a second transparent spacer.

27. A system for communication, the system comprising:

an optical assembly coupled to a surface of a photonic chip, the optical assembly comprising a lens array on the surface of the photonic chip, a mirror, a transparent spacer, a plurality of thin film filters, a second lens array on the surface of the photonic chip, a second mirror, and a second plurality of thin film filters, the optical assembly being operable to:

receive an input optical signal comprising a plurality of optical signals at different wavelengths;

communicating the plurality of optical signals through the transparent spacer;

pass a first of the plurality of optical signals through a corresponding one of the plurality of thin film filters while reflecting others of the plurality of optical signals back into the transparent spacer;

reflect the others of the plurality of optical signals towards a second of the plurality of thin film filters via a reflective surface of the transparent spacer;

pass one of the others of the plurality of optical signals through the second of the plurality of thin film filters; and

reflect the passed optical signals into the photonic chip using the mirror.

28. The system according to claim 27 , wherein each of the plurality of thin film filters is configured for one of the different wavelengths of the plurality of optical signals.

29. The system according to claim 27 , wherein the input optical signal is a coarse wavelength division multiplexed (CWDM) signal.

30. The system according to claim 27 , wherein the optical assembly is operable to receive a second input optical signal comprising a second plurality of optical signals at different wavelengths at a second transparent spacer.