CHANNEL-SWITCHED CROSS-CONNECT

• US 20020076149A1
• Filed: 02/15/2001
• Published: 06/20/2002
• Est. Priority Date: 11/04/1999
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Deacon, David A.G.
• Granted Patent: US 6,393,186 B1
• Time in Patent Office: Days
• US Class Current: 385/27
• CPC Class Codes: G02B 2006/12119 Bend
• CPC Class Codes: G02B 6/1228 Tapered waveguides, e.g. integrated spot-size transformers for coupling with fibres G02B6/305
• CPC Class Codes: G02B 6/30 for use between fibre and thin-film device
• CPC Class Codes: G02B 6/42 Coupling light guides with opto-electronic elements
• CPC Class Codes: G02B 6/4201 Packages, e.g. shape, construction, internal or external details
• CPC Class Codes: G02B 6/4266 Thermal aspects, temperature control or temperature monitoring thermal aspect of electrical circuits H05K7/20, H05K5/0213, temperature control in general G05D23/19
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 1/065 in an optical waveguide structure
• CPC Class Codes: G02F 1/3132 of directional coupler type
• CPC Class Codes: G02F 2201/307 Reflective grating, i.e. Bragg grating
• CPC Class Codes: H01S 5/0612 controlled by temperature
• CPC Class Codes: H01S 5/141 using a wavelength selective device, e.g. a grating or etalon H01S5/146 takes precedence

Abstract

The several embodiments of the invention include digitally tunable laser source, add-drop and cross connect devices, a tapered waveguide, a lensed waveguide, an asymmetric waveguide pair, a temperature sensor, and a tunable laser array, as well as methods for making and tuning these devices. The laser source, add-drop, and cross connect devices include materials with negative dependence of refractive index on temperature and temperature independent coincidence between resonator modes and a set of specified frequencies, e.g. for DWDM telecommunications channels. The free spectral range may be adjusted to equal a rational fraction of the specified frequency interval. The operating frequency may be selected by a thermo-optically tuned feedback element without substantially tuning the cavity modes. This can be accomplished by means of a waveguide pair with differential thermal response. The operating frequency may be induced to hop digitally between the specified frequencies. In a particular embodiment, semiconductor amplifier and polymer waveguide segments form a linear resonator with a thermo-optically tuned grating reflector. In a further embodiment, an amplifier and two waveguides from a tunable grating assisted coupler form a ring resonator. Tuning may also be accomplished by applying an electric field across a liquid crystal portion of the waveguide structure within the grating. The differential waveguide pair may also be used as a temperature or electric field sensor, or it may be used in a waveguide array to adjust a phase relationship, e.g. in an arrayed waveguide grating. A tapered waveguide may be used to couple different size waveguides, e.g. in a resonator having both a semiconductor diode amplifier waveguide and a planar waveguide structure for coupling to an optical fiber. A lensed planar waveguide may be used to couple to a different size waveguide, e.g. a semiconductor diode amplifier waveguide.

Claims

1. A method of tuning a multifrequency optical channel device, the device having first and second optical waveguide segments coupled to an athermal resonator by first and second frequency selective couplers actuated by a first and second electrode, respectively, said athermal resonator tuned for mode frequency overlap with a plurality of designated frequency channels, the method comprising:

detuning a first coupling frequency of the first coupler relative to a second coupling frequency of the second coupler to achieve a detuning condition in which the first waveguide is decoupled from the second waveguide at said first and second frequencies;

adjusting the first and second coupling frequencies to a vicinity of a desired frequency channel while maintaining said detuning condition; and

retuning the first coupling frequency relative to the second coupling frequency until the first and second frequencies substantially equal each other and the frequency of the desired channel.

2. The method of claim 1 wherein the device is adjusted from a first condition of coupling the first frequency equal to a first channel from the first into the second waveguide segment to a second condition of coupling the first frequency equal to a second channel from the first into the second waveguide segment.

3. The method of claim 2 wherein no other channels are coupled from the first into the second waveguide segment.

4. A method of tuning a multifrequency optical channel device, the device having first and second optical waveguide segments coupled to an athermal resonator by first and second frequency selective couplers actuated by a first and second electrode, respectively, said athermal resonator tuned for mode frequency overlap with a plurality of designated frequency channels, the method comprising:

detuning a first coupling frequency of the first coupler relative to a second coupling frequency of the second coupler to achieve a detuning condition in which the first waveguide is decoupled from the second waveguide at said first and second frequencies and at a third coupling frequency of the first coupler and at a fourth coupling frequency of the second coupler;

adjusting the third and fourth coupling frequencies to a vicinity of a desired frequency channel while maintaining said detuning condition; and

tuning the third coupling frequency relative to the fourth coupling frequency until the third and fourth frequencies substantially equal each other and the frequency of the desired channel.

5. The method of claim 4 wherein said adjusting step further comprises the steps of:

maintaining a further detuning condition in which the first waveguide is decoupled from the second waveguide at a fifth coupling frequency of the first coupler and a sixth frequency of the second coupler; and

tuning the fifth coupling frequency relative to the sixth coupling frequency and through an equality condition where the fifth and the sixth frequencies substantially equal each other at an intermediate frequency that does not equal any of the designated frequency channels.

6. A method of tuning a multifrequency optical channel device, the device having a first optical waveguide segment coupled to an resonator by a first frequency selective coupler actuated by an electrode, said resonator tuned for mode frequency overlap with a plurality of designated frequency channels, the method comprising:

selecting a desired one of said designated frequency channels; and

actuating said electrode to modify a coupling frequency of said first coupler in order to induce substantial coupling between the first waveguide segment and the resonator at the frequency of said desired channel.

7. The method of claim 6 wherein said resonator is athermal.

8. The method of claim 6 further comprising:

suppressing coupling between the first waveguide and the resonator at the frequency of an undesired channel.

9. The method of claim 6 wherein said first frequency selective coupler is thermo-optic said electrode is a heater, and wherein said actuating step further comprises the steps of:

passing current through said heater electrode; and

heating the first frequency selective coupler.

10. The method of claim 6 wherein a mode frequency of the resonator remains substantially constant during said actuating step.

11. The method of claim 6 wherein said first frequency selective coupler is a grating assisted coupler and said optical coupling is accomplished by reflecting optical energy from the grating.

12. The method of claim 6 wherein said first frequency selective coupler is a grating assisted coupler and said optical coupling is accomplished by codirectional coupling.

13. The method of claim 6 wherein said first frequency selective coupler is electro-optic said electrode is an electric field applying structure, and wherein actuating said electrode further comprises the steps of:

connecting a voltage to said electrode; and

applying an electric field across the first frequency selective coupler.

14. The method of claim 6 wherein said resonator is impedance matched for coupling an input optical beam in the first waveguide segment at the frequency of said desired channel to an output optical beam, and further comprising the step of:

coupling substantially all of the input optical beam at the frequency of said desired channel out of the first waveguide segment.

15. The method of claim 14 further comprising a second waveguide coupled to the resonator by a second frequency selective coupler, and wherein the output optical beam is in the second waveguide.

16. The method of claim 6 further comprising an optical frequency source coupled to a second waveguide segment, said second waveguide segment coupled to the resonator by a second frequency selective coupler, and further comprising the steps of:

coupling a source optical beam from second waveguide segment into the first waveguide segment at the frequency of said desired channel.

17. The method of claim 16 wherein said resonator is impedance matched for coupling an input optical beam in the first waveguide segment at the frequency of said desired channel to an output optical beam in the second waveguide segment, and further comprising the step of:

coupling substantially all of the source optical beam at the frequency of said desired channel out of the second waveguide segment.

19. The method of claim 18 wherein said resonator is athermal.

20. The method of claim 18 further comprising:

suppressing coupling between the first waveguide and the resonator at the frequency of an undesired channel.

21. The method of claim 18 wherein said first differential waveguide coupler is thermo-optic said electrode is a heater, and wherein said actuating step further comprises the steps of:

passing current through said heater electrode; and

heating the first differential waveguide coupler.

22. The method of claim 18 wherein a mode frequency of the resonator remains substantially constant during said actuating step.

23. The method of claim 18 wherein said first differential waveguide coupler is electro-optic said electrode is an electric field applying structure, and wherein actuating said electrode further comprises the steps of:

connecting a voltage to said electrode; and

applying an electric field across the first differential waveguide coupler.

24. The method of claim 18 wherein said resonator is impedance matched for coupling an input optical beam in the first waveguide segment at the frequency of said desired channel to an output optical beam, and further comprising the step of:

coupling substantially all of the input optical beam at the frequency of said desired channel out of the first waveguide segment.

25. The method of claim 24 further comprising a second waveguide coupled to the resonator by a second differential waveguide coupler, and wherein the output optical beam is in the second waveguide.

26. The method of claim 18 further comprising an optical frequency source coupled to a second waveguide segment, said second waveguide segment coupled to the resonator by a second differential waveguide coupler, and further comprising the steps of:

coupling a source optical beam from second waveguide segment into the first waveguide segment at the frequency of said desired channel.

27. The method of claim 26 wherein said resonator is impedance matched for coupling an input optical beam in the first waveguide segment at the frequency of said desired channel to an output optical beam in the second waveguide segment, and further comprising the step of:

coupling substantially all of the source optical beam at the frequency of said desired channel out of the second waveguide segment.

29. The method of claim 28 further comprising:

suppressing coupling between the first waveguide and the resonator at the frequency of an undesired channel.

30. The method of claim 28 wherein said first frequency selective coupler is thermo-optic said electrode is a heater, and wherein said actuating step further comprises the steps of:

passing current through said heater electrode; and

heating the first frequency selective coupler.

31. The method of claim 28 wherein said first frequency selective coupler is a grating assisted coupler and said optical coupling is accomplished by reflecting optical energy from the grating.

32. The method of claim 28 wherein said first frequency selective coupler is a grating assisted coupler and said optical coupling is accomplished by codirectional coupling.

33. The method of claim 28 wherein said first frequency selective coupler is electro-optic said electrode is an electric field applying structure, and wherein actuating said electrode further comprises the steps of:

connecting a voltage to said electrode; and

applying an electric field across the first frequency selective coupler.

34. The method of claim 28 wherein said resonator is substantially impedance matched for coupling an input optical beam in the first waveguide segment at the frequency of said desired channel to an output optical beam, and further comprising the step of:

coupling substantially all of the input optical beam at the frequency of said desired channel out of the first waveguide segment.

35. The method of claim 34 further comprising a second waveguide coupled to the resonator by a second frequency selective coupler, and wherein the output optical beam is in the second waveguide.

36. The method of claim 28 further comprising an optical frequency source coupled to a second waveguide segment, said second waveguide segment coupled to the resonator by a second frequency selective coupler, and further comprising the steps of:

coupling a source optical beam from second waveguide segment into the first waveguide segment at the frequency of said desired channel.

37. The method of claim 36 wherein said resonator is substantially impedance matched for coupling an input optical beam in the first waveguide segment at the frequency of said desired channel to an output optical beam in the second waveguide segment, and further comprising the step of:

coupling substantially all of the source optical beam at the frequency of said desired channel out of the second waveguide segment.

18. A method of tuning a multifrequency optical channel device, the device having a first optical waveguide segment coupled to an resonator by a first differential waveguide coupler actuated by an electrode, said resonator tuned for mode frequency overlap with a plurality of designated frequency channels, the method comprising:

selecting a desired one of said designated frequency channels; and

actuating said electrode to modify a coupling strength of said first coupler in order to induce substantial coupling between the first waveguide segment and the resonator at the frequency of said desired channel.

28. A method of tuning a multifrequency optical channel device, the device having a first optical waveguide segment coupled to an athermal resonator by a first frequency selective coupler actuated by an electrode, said athermal resonator tuned for mode frequency overlap with a plurality of designated frequency channels, the method comprising:

selecting a desired one of said designated frequency channels;

actuating said electrode to modify a coupling frequency of said first coupler in order to induce substantial coupling between the first waveguide segment and the resonator at the frequency of said desired channel, wherein a mode frequency of the resonator remains substantially constant during said actuating.