Thermally tunable optical devices

• US 6,411,746 B1
• Filed: 01/18/2000
• Issued: 06/25/2002
• Est. Priority Date: 01/18/2000
• Status: Expired due to Term

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: McNeilly, Peter J., Chen, Gang, Dawes, Steven B., Weller-Brophy, Laura A., Ouyang, Mike X., Chamberlain, Darol
• Primary Examiner(s): Lee, John D.
• Application Number:
  US09/484,491
• Time in Patent Office: 889 Days
• Field of Search: 385/1, 385/2, 385/8, 385/10, 385/12, 385/15, 385/27, 385/31, 385/37, 385/39, 385/40, 385/101, 385/123, 385/128, 385/140, 385/147
• US Class Current: 385/2
• CPC Class Codes: G02F 1/0115 in optical fibres
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 2201/307 Reflective grating, i.e. Bragg grating
• CPC Class Codes: G05D 23/24 the sensing element having a resistance varying with temperature, e.g. a thermistor

Abstract

The present invention relates to a tunable optical device 10 that includes an optical fiber device 12 having optical properties that vary with temperature and a heater 14. The heater 14 is thermally coupled to the optical fiber device 12. The heater 14 includes a metal layer 18 and two electrical contacts 20, 22 that are electrically connected to the metal layer 18. The electrical contacts 20, 22 are spaced apart from one another along the metal layer 18. The electrical resistance of the portion of the metal layer 18 between the contacts 20, 22 varies with temperature and serves as a resistive heater. The invention also includes a controller 16 that is electrically connected to the heater 14. The controller 16 provides electrical power to the heater 14 and measures the electrical voltage across the heater 14. The controller 16 compares the measured electrical voltage to a pre-selected reference value. The controller then regulates the amount of electrical current supplied to the heater 14. By regulating the amount of electrical current supplied to the heater 14 the temperature of the heater 14 is controlled.

Claims

1. A tunable optical device comprising:

an optical fiber device having an optical property that varies with temperature;

a metal layer thermally coupled to said optical fiber device, having an electrical resistance that varies with temperature;

a first electrical contact electrically connected to said metal layer;

a second electrical contact electrically connected to said metal layer, wherein said first and second electrical contacts are separated by a certain distance;

a power source electrically connected to said first and second electrical contacts; and

a controller electrically connected to said first and second electrical contacts that measures the electrical resistance of the metal layer between said first and second electrical contacts, wherein said controller compares the measured electrical resistance to a pre-selected resistance and regulates said measured electrical resistance by varying the amount of electrical power supplied by said power source.

2. The tunable optical device of claim 1 further comprising:

a substrate having a groove engageable with said optical fiber device, wherein said metal layer is disposed between said optical fiber device and the sides of said groove.

3. The tunable optical device of claim 2 wherein said substrate is a tube.

4. The tunable optical device of claim 1 wherein said metal layer is deposited on said optical fiber device.

5. The tunable optical device of claim 1 wherein said controller comprises:

an amplifier that generates an electrical signal proportionate to a difference between said metal layer resistance and a reference resistance.

6. The tunable optical device of claim 1 wherein said controller further comprises:

a resistor electrically connected to said metal layer.

7. The tunable optical device of claim 1 wherein said controller comprises:

a resistor electrically connected in series with said metal layer;

a voltage detector electrically connected to said first and second electrical contacts, that measures the voltage between said first and second electrical contacts;

a current detector electrically connected to said resistor, that measures the electrical current in said resistor;

a resistance calculator electrically connected to said voltage detector and said current detector, that determines the electrical resistance of said metal layer between said first and second electrical contacts and generates an electrical signal corresponding to said determined electrical resistance; and

an error detector that compares said electrical signal to a reference signal and generates a control signal, which regulates the electrical power supplied by said power source.

8. The tunable optical device of claim 1 wherein said controller comprises:

a resistor electrically connected in series with said metal layer;

a voltage detector disposed to measure the voltage between said first and second electrical contacts, that generates a first signal corresponding to said measured voltage;

a current detector disposed to measure the electrical current in said resistor, that generates a second signal corresponding to said measured current;

a resistance calculator disposed to receive said first and second signals, that uses said first and second signals to generate a third signal corresponding to the resistance of said metal layer; and

an error detector that receives said third signal and compares it to a pre-selected reference value and generates a control signal that regulates said power source.

9. The tunable optical device of claim 1 wherein said controller comprises:

a plurality of resistors electrically connected with said metal layer to form a Wheatstone bridge;

a digital controller that generates a target voltage;

a first amplifier having its gain controlled by said target voltage, wherein said first amplifier generates an electrical signal proportionate to a difference between the electrical resistance of said metal layer and the electrical resistance of at least one of said plurality of resistors; and

a transistor electrically disposed between said power source and said metal layer, wherein said transistor receives said electrical signal from said first amplifier.

10. A tunable optical device comprising:

an optical fiber device, wherein the optical properties of said optical fiber device vary with temperature;

a substrate having a groove, said groove disposed to engage said optical fiber device;

a resistive metal layer deposited on at least a portion of said groove, having an electrical resistance that varies with temperature;

a first electrical contact electrically connected to said resistive metal layer;

a second electrical contact electrically connected to said resistive metal layer, wherein said first and second electrical contacts are separated by a certain distance; and

a controller connected to said first and second electrical contacts, wherein said controller monitors the electrical resistance of said resistive metal layer between said first and second electrical contacts and adjusts said electrical resistance by applying electrical power to said first and second electrical contacts.

11. The tunable optical fiber device of claim 10 wherein said substrate is a glass cylinder.

12. The tunable optical fiber device of claim 10 further comprising an adhesive that bonds said optical fiber device to said substrate.

13. The tunable optical fiber device of claim 12 wherein said fiber based device is a tapered fiber device.

14. The tunable optical fiber device of claim 12 wherein said fiber based device is chosen from the group consisting of fiber Bragg gratings, long period gratings and Mach-Zehnder devices.

15. The tunable optical device of claim 10 wherein the controller includes:

two precision resistors;

a variable resistor, wherein the two precision resistors and the variable resistor are electrically connected with said metal layer to form a Wheatstone bridge;

a power source for supplying electrical power to said Wheatstone bridge; and

an error detection circuit that provides a control signal to said power source.

16. The tunable optical device of claim 15 wherein the resistance of the resistive metal layer is selected by adjusting the electrical resistance of said variable resistor.

17. A tunable optical device comprising:

an optical fiber device, wherein the optical properties of said optical fiber device vary with temperature;

a resistive heater disposed to substantially surround said optical fiber device, said resistive heater having an electrical resistance that varies with temperature, said heater converting electrical power to thermal energy;

an electrical power source electrically connected to said heater, said electrical power source supplying electrical power to said heater;

a sensor that measures said electrical resistance;

a comparator that compares said electrical resistance to a reference resistance and generates an output signal; and

a controller that uses said output signal to regulate the amount of electrical power delivered to said heater.

18. A tunable optical device comprising:

a fiber bragg grating;

a heater disposed to substantially surround said fiber bragg grating, said heater having an electrical resistance that varies with temperature, said heater converting electrical power to thermal energy;

an electrical power source electrically connected to said heater, said electrical power source supplying electrical power to said heater;

a sensor that measures said electrical resistance;

a comparator that compares said electrical resistance to a reference resistance and generates an output signal; and

a controller that uses said output signal to regulate the amount of electrical power delivered to said heater.

19. A tunable optical device comprising:

an optical filter having optical properties that vary with temperature;

a heater thermally coupled to said optical filter, said heater having an electrical resistance that changes with temperature, wherein said heater converts electrical power to thermal energy; and

a controller electrically connected to said heater, said controller measuring said electrical resistance and providing electrical power to said heater, wherein said controller compares said electrical resistance to a target electrical resistance and adjust the amount of electrical power provided to bring said electrical resistance into a range with said target electrical resistance.

20. A tunable optical device comprising:

an optical fiber device having optical properties that vary with temperature;

a plurality of heaters thermally coupled to said optical fiber device disposed along the length of said optical fiber device, each of said plurality of heaters having an electrical resistance that changes with temperature, wherein each of said plurality of heaters converts electrical power to thermal energy; and

a controller electrically connected to said plurality of heaters, said controller measuring said electrical resistances and providing electrical power to said plurality of heaters, wherein said controller compares said electrical resistances to at least one target electrical resistance and adjusts the amount of electrical power provided to bring said electrical resistances into a range with said at least one target electrical resistance.

21. The tunable optical device of claim 20 wherein each of said plurality of heaters comprises a resistive heating element.

22. The tunable optical device of claim 21 wherein said resistive heating element is a metal layer.

23. The tunable optical device of claim 20 further comprising a substrate disposed to support said plurality of heaters.

24. A tunable optical device comprising:

an optical fiber device having optical properties that vary with temperature;

a heater thermally coupled to said optical fiber device, said heater having an electrical resistance that changes with temperature, wherein said heater converts electrical power to thermal energy;

a power source electrically connected to said heater;

a transistor electrically disposed between said power source and said heater; and

a controller having;

a plurality of resistors electrically connected to said heater to form a Wheatstone bridge circuit;

an error detector electrically connected to said Wheatstone bridge circuit, wherein said error detector determines the electrical state of said Wheatstone bridge circuit and generates an electrical signal corresponding to the electrical state of said Wheatstone bridge circuit;

a gain controller electrically connected to said error detector, wherein said gain controller generates a gain control signal that controls the operating properties of said optical fiber device; and

a summing device electrically connected to said transistor and disposed to receive said electrical signal generated by said error detector, wherein said summing device generates a transistor control signal, said transistor control signal regulating the electrical power supplied to said heater by said power source.

25. A tunable optical device comprising:

an optical waveguide device having an optical property that varies with temperature;

a metal layer thermally coupled to said optical waveguide device, having an electrical resistance that varies with temperature;

a first electrical contact electrically connected to said metal layer;

a second electrical contact electrically connected to said metal layer, wherein said first and second electrical contacts are separated by a certain distance;

a power source electrically connected to said first and second electrical contacts; and

a controller electrically connected to said first and second electrical contacts that measures the electrical resistance of the metal layer between said first and second electrical contacts, wherein said controller compares the measured electrical resistance to a pre-selected resistance and regulates said measured electrical resistance by varying the amount of electrical power supplied by said power source.

26. The tunable optical device of claim 25 wherein said metal layer is deposited on said optical waveguide device.

27. The tunable optical device of claim 25 wherein said controller comprises:

an amplifier that generates an electrical signal proportionate to a difference between said metal layer resistance and a reference resistance.

28. The tunable optical device of claim 25 wherein said controller further comprises:

a resistor electrically connected to said metal layer.

29. The tunable optical device of claim 25 wherein said controller comprises:

a resistor electrically connected in series with said metal layer;

a voltage detector electrically connected to said first and second electrical contacts, that measures the voltage between said first and second electrical contacts;

a current detector electrically connected to said resistor, that measures the electrical current in said resistor;

a resistance calculator electrically connected to said voltage detector and said current detector, that determines the electrical resistance of said metal layer between said first and second electrical contacts and generates an electrical signal corresponding to said determined electrical resistance; and

an error detector that compares said electrical signal to a reference signal and generates a control signal, which regulates the electrical power supplied by said power source.

30. The tunable optical device of claim 25 wherein said controller comprises:

a resistor electrically connected in series with said metal layer;

a voltage detector disposed to measure the voltage between said first and second electrical contacts, that generates a first signal corresponding to said measured voltage;

a current detector disposed to measure the electrical current in said resistor, that generates a second signal corresponding to said measured current;

a resistance calculator disposed to receive said first and second signals, that uses said first and second signals to generate a third signal corresponding to the resistance of said metal layer; and

an error detector that receives said third signal and compares it to a pre-selected reference value and generates a control signal that regulates said power source.

31. The tunable optical device of claim 25 wherein said controller comprises:

a plurality of resistors electrically connected with said metal layer to form a Wheatstone bridge;

a digital controller that generates a target voltage;

a first amplifier having its gain controlled by said target voltage, wherein said first amplifier generates an electrical signal proportionate to a difference between the electrical resistance of said metal layer and an electrical resistance of at least one of said plurality of resistors; and

a transistor electrically disposed between said power source and said metal layer, wherein said transistor receives said electrical signal from said first amplifier.

32. A tunable optical device comprising:

an optical waveguide device, wherein the optical properties of said optical waveguide device vary with temperature;

a resistive heater disposed to substantially surround said optical waveguide device, said resistive heater having an electrical resistance that varies with temperature, said heater converting electrical power to thermal energy;

an electrical power source electrically connected to said resistive heater, said electrical power source supplying electrical power to said resistive heater;

a sensor that measures said electrical resistance;

a comparator that compares said electrical resistance to a reference resistance and generates an output signal; and

a controller that uses said output signal to regulate the amount of electrical power delivered to said resistive heater.