Coupled optical waveguide resonators with heaters for thermo-optic control of wavelength and compound filter shape
An integrated optical device is disclosed comprising a substrate, optical waveguide, and compound optical resonator having a temperature sensor, at least two coupled optical resonators, and a heater localized to each optical resonator. An optical input signal is coupled to one of the resonators making up the compound resonator to form an optical output signal. The center wavelength and shape of the output signal is optimized with a feedback loop using the temperature sensor to control the power dissipated in at least one of the localized heaters. The power dissipated in the remaining resonator heaters is set according to a predetermined function having as an input variable the power dissipated in the resonant heater under control of the said feedback loop.
1. A device comprising:
a substrate;
at least one optical waveguide residing on the substrate;
at least one compound optical resonator optically coupled with the at least one optical waveguide, wherein said compound optical resonator; wherein the device is an integrated optical device having multiple layers and having at least two optical waveguides residing on different layers comprises at least two coupled optical resonators;
first and second subsets of heaters, each of the heaters in the first and second subsets being localized to at least one of said optical resonator; and
a temperature sensor localized to at least two of the coupled optical resonators of said compound optical resonator.
2. The device of claim 1 wherein
power dissipated in the first subset of heaters is adjusted to maintain the temperature sensor at a value;
power dissipated in the second subset of heaters is adjusted as a function of the power dissipated in the first subset of heaters.
3. The device of claim 1 wherein
the first and second subsets of heaters cooperate to comprise an integer number of heaters N;
power dissipated in a power controlled heater within the first or second subsets of heaters is actively controlled to maintain the temperature sensor at a value; and
power dissipated in the remaining (N−1) heaters is adjusted as functions of the power dissipated in the power controlled heater.
4. The device of claim 3 , further comprising a control loop actively controlling the power in the power controlled heater.
5. The device of claim 3 wherein the power dissipated in each of the remaining (N−1) heaters is a linear function of the power dissipated in the power controlled heater.
6. The device of claim 3 wherein the power dissipated in each of the remaining (N−1) heaters is a polynomial function of the power dissipated in the power controlled heater.
7. The device of claim 3 wherein the power dissipated in each of the remaining (N−1) heaters is a second order polynomial function of the power dissipated in the power controlled heater.
8. The device of claim 3 wherein power is supplied to the heaters using pulse width modulation (PWM).
9. The device of claim 1 wherein the heaters are resistive heaters.
10. The device of claim 9 wherein the resistive heaters are metal films.
11. The device of claim 10 wherein the resistance of the resistive heaters is between 10 and 500 ohms.
12. The device of claim 10 wherein the metal film comprises one or more of the elements platinum, gold, nickel, chrome, aluminum, and tungsten.
13. The device of claim 1 wherein the heaters comprise a Peltier thermo-electric element.
14. The device of claim 1 wherein the temperature sensor comprises a resistive temperature device (RTD).
15. The device of claim 14 wherein the resistive temperature device comprises a metal film resistor or a thermistor.
16. The device of claim 14 wherein the resistive temperature device has a resistance between 100 and 10000 ohms.
17. The device of claim 1 wherein the temperature sensor is a platinum film resistor.
18. The device of claim 1 wherein the temperature sensor comprises a thermocouple.
19. The device of claim 1 wherein the optical waveguide comprises a ridge, rib, trench, filled trench or strip-loaded design.
20. The device of claim 1 wherein the optical waveguide comprises a core and a cladding.
21. The device of claim 20 wherein the core has lateral or vertical dimensions of between 0.5 and 5 microns.
22. The device of claim 1 wherein the optical resonator comprises a core and a cladding.
23. The device of claim 22 wherein the core has lateral or vertical dimensions of between 0.5 and 5 microns.
24. The device of claim 1 further comprising a second optical waveguide wherein the optical waveguide and the second optical waveguide are each optically coupled with a separate one of the optical resonators.
25. The device of claim 1 wherein the integrated optical device is a planar lightwave circuit or a photonic integrated circuit.
26. The device of claim 1 wherein the optical resonators have a dn/dT magnitude of between 1×10 −5 and 5×10 −5 .
27. The device of claim 1 wherein the optical resonators and optical waveguide are substantially transparent at a wavelength between 1460 nm and 1625 nm.
28. The device of claim 27 wherein at a wavelength between 1460 nm and 1625 nm the optical loss is less than 0.5 dB/cm.
29. The device of claim 1 , further comprising a control system maintaining the substrate at a predetermined temperature.