Passive thermo-optic feedback for robust athermal photonic systems

• US 9,063,354 B1
• Filed: 02/07/2012
• Issued: 06/23/2015
• Est. Priority Date: 02/07/2012
• Status: Active Grant

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Rakich, Peter T., Watts, Michael R., Nielson, Gregory N.
• Primary Examiner(s): Lepisto, Ryan
• Assistant Examiner(s): ANDERSON, GUY G
• Application Number:
  US13/368,127
• Time in Patent Office: 1,232 Days
• Field of Search: 385/14, 385/16, 385/27, 398/83, 398/85
• US Class Current: 1/1
• CPC Class Codes: G02B 6/02176 due to temperature fluctuations
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/29338 Loop resonators
• CPC Class Codes: G02B 6/29389 Bandpass filtering, e.g. 1x1 device rejecting or passing certain wavelengths G02B6/2938 takes precedence
• CPC Class Codes: G02B 6/29398 Temperature insensitivity
• CPC Class Codes: G02B 6/35 having switching means by changing the optical properties of the medium G02F1/00
• CPC Class Codes: G02B 6/3576 Temperature or heat actuation thermal forces controlling reflecting elements in general G02B26/0866; thermo-optic devices G02F1/0147
• CPC Class Codes: G02B 6/3582 Housing means or package or arranging details of the switching elements, e.g. for thermal isolation
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 1/025 in an optical waveguide structure G02F1/017, G02F1/2257 take precedence
• CPC Class Codes: G02F 2203/15 involving resonance effects, e.g. resonantly enhanced interaction

Abstract

Thermal control devices, photonic systems and methods of stabilizing a temperature of a photonic system are provided. A thermal control device thermally coupled to a substrate includes a waveguide for receiving light, an absorption element optically coupled to the waveguide for converting the received light to heat and an optical filter. The optical filter is optically coupled to the waveguide and thermally coupled to the absorption element. An operating point of the optical filter is tuned responsive to the heat from the absorption element. When the operating point is less than a predetermined temperature, the received light is passed to the absorption element via the optical filter. When the operating point is greater than or equal to the predetermined temperature, the received light is transmitted out of the thermal control device via the optical filter, without being passed to the absorption element.

Claims

1. A thermal control device thermally coupled to a substrate comprising:

a waveguide for receiving light;

an absorption element, optically coupled to the waveguide, for converting the received light to heat; and

an optical filter optically coupled to the waveguide and thermally coupled to the absorption element, an operating point of the optical filter being tuned responsive to the heat from the absorption element,

wherein, when the operating point of the optical filter is less than a predetermined temperature, the received light is passed to the absorption element via the optical filter, and

when the operating point of the optical filter is greater than or equal to the predetermined temperature, the received light is transmitted out of the thermal control device via the optical filter, without being passed to the absorption element.

2. The thermal control device according to claim 1, wherein the light is converted to heat by the absorption element and is transferred to the substrate when the operating point of the optical filter is less than the predetermined temperature.

3. The thermal control device according to claim 1, wherein the operating point of optical filter is tuned relative to at least one wavelength of the received light and the predetermined temperature is associated with the at least one wavelength of the received light.

4. The thermal control device according to claim 1, wherein the thermal control device is thermally coupled to the substrate via a thermal resistance.

5. The thermal control device according to claim 1, wherein the optical filter includes a plurality of optical filters and the absorption element includes a plurality of absorption elements thermally coupled to the respective plurality of optical filters, and

a combination of the plurality of absorption elements are configured to convert the received light into a predetermined amount of heat.

6. The thermal control device according to claim 1, wherein:

the optical filter includes a long-pass filter, a band edge of the long-pass filter corresponding to the operating point,

the absorption element is disposed adjacent to the long-pass filter and is optically coupled to the long-pass filter, and

the long-pass filter is disposed between the waveguide and the absorption element, such that the received light is transmitted out of the thermal control device via the waveguide, when the band edge of the long-pass filter is greater than or equal to the predetermined temperature.

7. The thermal control device according to claim 6, wherein the long-pass filter includes at least one of a Bragg reflector, a photonic crystal filter or a thin film interference filter.

8. The thermal control device according to claim 6, wherein the absorption element includes at least one of a doped waveguide structure or a thermally conductive element.

9. The thermal control device according to claim 6, wherein:

the band edge of the long-pass filter is greater than a wavelength of the received light when the long-pass filter is greater than or equal to the predetermined temperature, and

the band edge of the long-pass filter is less than the wavelength of the received light when the long-pass filter is less than the predetermined temperature.

10. The thermal control device according to claim 1, wherein:

the optical filter includes a microresonator filter, a resonance wavelength band of the microresonator filter corresponding to the operating point,

the absorption element is disposed adjacent to the waveguide, and

the microresonator filter is disposed between the waveguide and a further waveguide, such that the received light is transmitted out of the thermal control device via the further waveguide, when the resonance wavelength band of the microresonator filter is greater than or equal to the predetermined temperature.

11. The thermal control device according to claim 10, wherein the microresonator filter includes at least one of a ring microresonator, an oval microresonator, an elliptical microresonator or a racetrack microresonator.

12. The thermal control device according to claim 10, wherein the absorption element includes a doped waveguide structure and a thermally conductive element coupled between the doped waveguide structure and the microresonator filter.

13. The thermal control device according to claim 10, wherein:

a wavelength of the received light is on resonance with the resonance wavelength band of the microresonator filter when the resonance wavelength band is greater than or equal to the predetermined temperature, and

the wavelength of the received light is off resonance with the resonance wavelength band of the microresonator filter when the resonance wavelength is less than the predetermined temperature.

14. A photonic system comprising:

a light source for generating light having at least one wavelength; and

a thermal control device thermally coupled to an isothermal region of a photonic chip, the thermal control device comprising;

an optical filter configured to receive the light from the light source, and

an absorption element for converting the received light to heat, the optical filter thermally coupled to the absorption element, an operating point of the optical filter being tuned responsive to the heat from the absorption element to selectively transfer heat from the absorption element to the isothermal region,

wherein, when the operating point of the optical filter is less than a predetermined temperature, the received light is passed to the absorption element via the optical filter, and

when the operating point of the optical filter is greater than or equal to the predetermined temperature, the received light is transmitted out of the thermal control device via the optical filter, without being passed to the absorption element.

15. The photonic system according to claim 14, wherein the operating point of optical filter is tuned relative to the at least one wavelength of the light and the predetermined temperature is associated with the at least one wavelength of the light.

16. The photonic system according to claim 14, wherein the photonic system includes at least one photonic element thermally coupled to the isothermal region, the thermal control device transferring the heat to the at least one photonic element.

17. The photonic system according to claim 16, wherein the thermal control device passively controls an operating point of the photonic element.

18. The photonic system according to claim 14, wherein the thermal control device includes a plurality of thermal control devices thermally coupled to a respective plurality of isothermal regions of the photonic chip.

19. The photonic system according to claim 14, wherein the optical filter includes a plurality of optical filters and the absorption element includes a plurality of absorption elements thermally coupled to the respective plurality of optical filters, and

a combination of the plurality of absorption elements are configured to convert the received light into a predetermined amount of heat.

20. The photonic system according to claim 14, wherein the optical filter includes a long-pass filter, a band edge of the long-pass filter corresponding to the operating point.

21. The photonic system according to claim 14, wherein the optical filter includes a microresonator filter, a resonance wavelength of the microresonator filter corresponding to the operating point.

22. A method of stabilizing a temperature of a photonic system comprising:

receiving light by an optical filter;

selectively passing the received light to an absorption element responsive to an operating point of the optical filter, the optical filter thermally coupled to the absorption element such that the operating point of the optical filter is tuned responsive to heat from the absorption element;

when the operating point of the optical filter is less than a predetermined temperature;

passing the received light to the absorption element via the optical filter, and

converting the received light to the heat by the absorption element to transfer heat to the photonic system; and

when the operating point of the optical filter is greater than or equal to the predetermined temperature;

transmitting the received light out of the photonic system via the optical filter, without passing the received light to the absorption element, to reduce the temperature of the photonic system.

23. The method according to claim 22, wherein the tuning of the operating point of optical filter includes tuning the operating point relative to a wavelength of the received light, the predetermined temperature being associated with the wavelength of the received light.

24. The method according to claim 22, wherein the transferring of the heat to the photonic system including transferring the heat to an isothermal region of the photonic system via a thermal resistance.

25. The method according to claim 22, wherein the photonic system includes at least one photonic element thermally coupled to an isothermal region of the photonic system, the transferring of the heat to the photonic system including transferring the heat to the at least one photonic element.

26. The method according to claim 22, wherein the optical filter includes a plurality of optical filters and the absorption element includes a plurality of absorption elements thermally coupled to the respective plurality of optical filters, and

an absorption fraction of each absorption element is selected such that a combination of the plurality of absorption elements convert the received light into a predetermined amount of heat.