Integrated coherent optical detector

• US 7,483,600 B2
• Filed: 02/07/2007
• Issued: 01/27/2009
• Est. Priority Date: 07/02/2003
• Status: Active Grant

• Current Assignee: CeLight, Inc.
• Original Assignee: CeLight, Inc.
• Inventors: Harston, Geoffrey, Kaplan, Arkady, Shpantzer, Isaac, Achiam, Yaakov, Cho, Pak Shing, Greenblatt, Arthur
• Primary Examiner(s): Connelly-Cushwa; Michelle R.
• Assistant Examiner(s): CHU, CHRIS H
• Application Number:
  US11/672,372
• Publication Number:
  US 20070140613A1
• Time in Patent Office: 720 Days
• Field of Search: None
• US Class Current: 385/14
• CPC Class Codes: G02B 6/4225 by a direct measurement of the degree of coupling, e.g. the amount of light power coupled to the fibre or the opto-electronic element

Abstract

The present invention provides an integrated device and a method of its fabrication and use. Two parts of the device each having an electronic circuit are aligned adjacent to each other with an accuracy of at least 1 micron. An alignment system includes two parts: a first part integrated with the first electronic circuit of the integrated device on the first substrate and a second part integrated with the second electronic circuit of the integrated device on the second substrate. The second part of alignment system includes at least one photodiode. The maximal value of the photodiode current indicates the best alignment of two parts of the integrated device. In one embodiment the integrated device is a coherent optical detector for high speed optical communications and chemical sensing. In another embodiment the integrated optical device is a coherent optical detector operating in two polarization states of light.

Claims

1. An integrated optical device, comprising:

at least a first input and an alignment input, an optical interface having an interface circuit and a first alignment system both having integrated waveguides, the interface circuit and the first alignment system are adapted to operate at different non-overlapping time periods, the integrated waveguides of the interface circuit and the integrated waveguides of the first alignment system each having at least one output waveguide, the output waveguides of the interface circuit and the output waveguides of the first alignment system being essentially parallel each other, the first alignment system having at least one alignment waveguide to pass light from the alignment input to a first alignment system output, the first alignment waveguide having light intensity losses less than 2 dB, a receiving unit positioned adjacent to the optical interface with an accuracy of at least 10 micron in the direction essentially perpendicular the output waveguides, the receiving unit containing a receiving circuit and a second alignment system, the second alignment system having at least one photodetector positioned along the line of the first alignment system output waveguide, wherein the interface circuit and the first alignment system are each formed as part of a single planar chip.

2. The optical device of claim 1, wherein the accuracy of the receiving unit positioning is at least 1 micron.

3. The optical device of claim 1, wherein the accuracy of the receiving unit positioning is at least 0.1 micron.

4. The optical device of claim 1, wherein the photodetector is positioned adjacent to the first alignment system output.

5. The optical device of claim 1, wherein the second alignment system includes a receiving alignment waveguide connected to the photodetector, the receiving alignment waveguide having light intensity losses less than 2 dB.

6. The optical device of claim 1, wherein the receiving circuit and the second alignment system each formed as part of a single planar chip.

7. The optical device of claim 1, wherein the receiving circuit includes at least one photodiode.

8. The optical device of claim 1, wherein the optical device is an optical link device.

9. The optical device of claim 1, wherein the chip is a single piece of crystal.

10. The optical device of claim 1, wherein the chip is made of LiNbO.sub.3 and LiTaO.sub.3 cut at X, or Y, or Z planes.

11. The optical device of claim 1, wherein the chip material is a ferroelectric material.

12. The optical device of claim 1, wherein the chip material is a semiconductor material.

13. The optical device of claim 12, wherein the semiconductor material is selected from Si and InP.

14. The optical device of claim 1, wherein the optical interface comprises:

a first coupler coupled to the first input, the first coupler producing at least a first and second outputs;

a second coupler coupled to a second input, the second coupler producing at least a first and second outputs;

a third coupler coupled to the first output of the first coupler and to the first output of the second coupler;

a fourth coupler coupled to the second output of the first coupler and to the second output of the second coupler;

first and second crossing waveguides with an angle selected to minimize crosstalk and losses between the first and second cross waveguides, the first crossing waveguide connecting one of the first or second outputs from the first coupler with an input of the fourth coupler, the second crossing waveguide connecting one of the first or second outputs from the second coupler with an input of the third coupler;

a first phase shifter coupled to the first and second waveguides, the first and second waveguides connecting one of the outputs of the first or second coupler and one of the inputs of the third or fourth couplers.

15. The optical device of claim 14, wherein the optical device is an optical pointing device.

16. The optical device of claim 14, wherein the optical device is a tracking device.

17. The optical device of claim 14, further comprising:

a second phase shifter coupled to the first and second waveguides, the first and second waveguides connecting one of the outputs of the first or second coupler and one of the inputs of the third or fourth coupler.

18. The optical device of claim 1, wherein the optical interface comprises:

a first coupler coupled to the first input and producing at least a first and second output;

a second coupler coupled to a second input and producing at least a first and second output;

a third coupler coupled to the first output of the first coupler and to the first output of the second coupler;

a fourth coupler coupled to the second output of the first coupler and to the second output of the second coupler;

first and second crossing waveguides with an angle selected to minimize crosstalk and losses between the first and second cross waveguides, the first crossing waveguide connecting one of the first or second outputs from the first coupler with an input of the fourth coupler, the second crossing waveguide connecting one of the first or second outputs from the second coupler with an input of the third coupler;

a first phase shifter coupled to first and second waveguides, the first and second waveguides connecting one of the outputs of the first or second coupler and one of the inputs of the third or fourth couplers, a fifth coupler coupled to the second input and producing at least a first and second output;

a sixth coupler coupled to a third input and producing at least a first and second output;

a seventh coupler coupled to the first output of the fifth coupler and to the first output of the sixth coupler, an eighth coupler coupled to the second output of the fifth coupler and to the second output of the sixth coupler, third and fourth crossing waveguides with an angle selected to minimize crosstalk and losses between the third and fourth cross waveguides, the third crossing waveguide connecting one of the first or second outputs from the fifth coupler with an input of the eight coupler, the second crossing waveguide connecting one of the first or second outputs from the sixth coupler with an input of the seventh coupler, a third phase shifter coupled to third and fourth waveguides, the third and fourth waveguides are connected to one of the outputs of the fifth or sixth coupler and one of the inputs of the seventh or eighth coupler, wherein the first, second, third, fourth, fifth, sixth, seventh and eighth couplers, the two sets of crossing waveguides and the phase shifters are each formed as part of a single planar chip made of an electro-optical material.

19. A method of data transmission, comprising:

transmitting a light beam from a transmitter to a receiver, the light beam being modulated with data;

directing the light beam to a first input of the receiver, the receiver further comprising an alignment input, an optical interface having an interface circuit and a first alignment system both having integrated waveguides, the interface circuit and the first alignment system are adapted to operate at different non-overlapping time periods, the integrated waveguides of the interface circuit and the integrated waveguides of the first alignment system each having at least one output waveguide, the output waveguides of the interface circuit and the output waveguides of the first alignment system being essentially parallel each other, the first alignment system having at least one alignment waveguide to pass an alignment light from the alignment input to a first alignment system output, the first alignment waveguide having light intensity losses less than 2 dB, a receiving unit positioned adjacent to the optical interface with an accuracy of at least 10 micron in the direction essentially perpendicular the output waveguides, the receiving unit containing a receiving circuit and a second alignment system, the second alignment system having at least one photodetector positioned along the line of the first alignment system output waveguide, wherein the interface circuit and the first alignment system are each formed as part of a single planar chip.

20. The method of claim 19, wherein the transmission is in free space.

21. The method of claim 19, wherein the transmission is with a fiber.

22. The method of claim 19, wherein the transmission is applied to a ladar application.

23. The method of claim 19, wherein the transmission is utilized for spectral analysis.

24. An optical communication system, comprising:

a transmitter; and

a receiver receiving an optical beam modulated with data from the transmitter, the receiver including;

at least a first input for receiving the optical beam and an alignment input, an optical interface having an interface circuit and a first alignment system both having integrated waveguides, the interface circuit and the first alignment system are adapted to operate at different non-overlapping time periods, the integrated waveguides of the interface circuit and the integrated waveguides of the first alignment system each having at least one output waveguide, the output waveguides of the interface circuit and the output waveguides of the first alignment system being essentially parallel each other, the first alignment system having at least one alignment waveguide to pass light from the alignment input to a first alignment system output, the first alignment waveguide having light intensity losses less than 2 dB, a receiving unit positioned adjacent to the optical interface with an accuracy of at least 10 micron in the direction essentially perpendicular the output waveguides, the receiving unit containing a receiving circuit and a second alignment system, the second alignment system having at least one photodetector positioned along the line of the first alignment system output waveguide, wherein the interface circuit and the first alignment system are each formed as part of a single planar chip.

25. An optical communication system of claim 24, wherein the receiver further comprises:

a fifth coupler coupled to the second input and producing at least a first and second output;

a sixth coupler coupled to a third input and producing at least a first and second output;

a seventh coupler coupled to the first output of the fifth coupler and to the first output of the sixth coupler, an eighth coupler coupled to the second output of the fifth coupler and to the second output of the sixth coupler, third and fourth crossing waveguides with an angle selected to minimize crosstalk and losses between the third and fourth cross waveguides, the third crossing waveguide connecting one of the first or second outputs from the fifth coupler with an input of the eight coupler, the fourth crossing waveguide connecting one of the first or second outputs from the sixth coupler with an input of the seventh coupler, a third phase shifter coupled to third and fourth waveguides, the third and fourth waveguides are connected to one of the outputs of the fifth or sixth coupler and one of the inputs of the seventh or eighth coupler, wherein the first, second, third, fourth, fifth, sixth, seventh and eighth couplers, the two sets of crossing waveguides and the phase shifters are each formed as part of a single planar chip made of an electro-optical material.

26. An optical communication system, comprising:

a transmitter transmitting an optical beam modulated with data to a receiver;

the receiver including;

a first coupler coupled to the first input and producing at least a first and second output;

a second coupler coupled to the second input and producing at least a first and second output;

a third coupler coupled to the first output of the first coupler and to the first output of the second coupler;

a fourth coupler coupled to the second output of the first coupler and to the second output of the second coupler;

first and second crossing waveguides with an angle selected to minimize crosstalk and losses between the first and second cross waveguides, the first crossing waveguide connecting one of the first or second Outputs from the first coupler with an input of the fourth coupler, the second crossing waveguide connecting one of the first or second outputs from the second coupler with an input of the third coupler;

a first phase shifter coupled to the first and second waveguides, the first and second waveguide being connected to one of the outputs of the first or second coupler and one of the inputs of the third or fourth coupler, an alignment system, the alignment system including at least one waveguide and at least one photodetector, the first, second, third and fourth couplers, the two crossing waveguides, the phase shifter and the alignment system are each formed as part of a single planar chip made of an electro-optical material, wherein the transmitter comprises;

a first Mach-Zehnder modulator that produces a first output;

a second Mach-Zehnder modulator that produces a second output;

a splitter coupled to the first and second Mach-Zehnder modulators;

a combiner that combines the first and second outputs; and

a phase shifter coupled to the first and second Mach-Zehnder modulators, wherein the-first Mach-Zehnder modulator, the second Mach-Zehnder modulator, the splitter, the combiner and the phase shifter are formed as part of a single planar chip made of electro-optical material.

27. An optical communication system, comprising:

a transmitter transmitting an optical beam modulated with data to a receiver, the receiver including;

a first coupler coupled to the first input and producing at least a first and second output;

a second coupler coupled to the second input and producing at least a first and second output;

a third coupler coupled to the first output of the first coupler and to the first output of the second coupler;

a fourth coupler coupled to the second output of the first coupler and to the second output of the second coupler;

first and second crossing waveguides with an angle selected to minimize crosstalk and losses between the first and second cross waveguides, the first crossing waveguide connecting one of the first or second outputs from the first coupler with an input of the fourth coupler, the second crossing waveguide connecting one of the first or second outputs from the second coupler with an input of the third coupler;

a first phase shifter coupled to the first and second waveguides, the first and second waveguide being connected to one of the outputs of the first or second coupler and one of the inputs of the third or fourth coupler, an alignment system, the alignment system including at least one waveguide and at least one photodetector;

the receiver further comprises;

a fifth coupler coupled to the second input and producing at least a first and second output;

a sixth coupler coupled to a third input and producing at least a first and second output;

a seventh coupler coupled to the first output of the fifth coupler and to the first output of the sixth coupler, an eighth coupler coupled to the second output of the fifth coupler and to the second output of the sixth coupler, third and fourth crossing waveguides with an angle selected to minimize crosstalk and losses between the third and fourth cross waveguides, the third crossing waveguide connecting one of the first or second outputs from the fifth coupler with an input of the eight coupler, the fourth crossing waveguide connecting one of the first or second outputs from the sixth coupler with an input of the seventh coupler, a third phase shifter coupled to third and fourth waveguides, the third and fourth waveguides are connected to one of the outputs of the fifth or sixth coupler and one of the inputs of the seventh or eighth coupler, the first, second, third, fourth, fifth, sixth, seventh and eighth couplers, the two sets of crossing waveguides, the phase shifters and the alignment system are each formed as part of a single planar chip made of an electro-optical material;

wherein the transmitter comprises;

a first Mach-Zehnder modulator that produces a first MZ output;

a second Mach-Zehnder modulator that produces a second MZ output;

a third Mach-Zehnder modulator that produces a third MZ output;

a fourth Mach-Zehnder modulator that produces a fourth MZ output;

a first input splitter coupled to the first and second Mach-Zehnder modulators;

a first phase shifter coupled to the first MZ and second MZ outputs;

a first output combiner positioned to combine the first MZ and second MZ outputs from the first and second Mach-Zehnder modulators;

a second input splitter coupled to the third and fourth Mach-Zehnder modulators;

a second phase shift coupled to the third MZ and fourth MZ outputs; and

a second output combiner positioned to combine the third MZ and fourth MZ outputs.