Semiconductor micro-resonator for monitoring an optical device

• US 20040223697A1
• Filed: 06/15/2004
• Published: 11/11/2004
• Est. Priority Date: 04/26/2002
• Status: Active Grant

• Current Assignee: Broadcom International Pte Ltd. (Broadcom, Inc.)
• Original Assignee: Apogee Photonics, Inc. (Broadcom, Inc.)
• Inventors: Frateschi, Newton C., Andersen, John Kai
• Granted Patent: US 7,016,556 B2
• Time in Patent Office: Days
• US Class Current: 385/39
• CPC Class Codes: G01J 3/0205 Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
• CPC Class Codes: G01J 3/0216 using light concentrators or collectors or condensers
• CPC Class Codes: G01J 3/0259 Monolithic
• CPC Class Codes: G01J 3/12 Generating the spectrum; Monochromators
• CPC Class Codes: H01S 5/026 Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers stabilisation of output H01S5/06
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser

Abstract

An optical device includes an optical waveguide through which light propagates and a micro-resonator structure including an optical sensor. The micro-resonator is configured to resonate at a wavelength of light that may be transmitted through the optical waveguide. When light at that wavelength is transmitted through the optical waveguide, it resonates in the resonator and is detected by the optical sensor to produce an electrical signal. The optical resonator may be a micro-cylinder, disc or ring resonator and may be coupled to the waveguide via evanescent coupling or leaky-mode coupling. Multiple resonators may be implemented proximate to the waveguide to allow multiple wavelengths to be detected. When the waveguide is coupled to a tunable laser, signals provided by the optical sensor may be used to tune the wavelength of the laser.

Claims

1. A monitored optical device comprising:

an optical waveguide through which light propagates; and

a plurality of micro-resonator structures optically coupled to the waveguide, each micro-resonator including an optical sensor configured to provide a respectively different electrical output signal,

wherein each of the plurality of micro-resonator structures is configured to resonate when light at a respectively different predetermined wavelength propagates through the optical waveguide and to provide the electrical output signal having a peak value in response to light at the respective predetermined wavelength.

2. A monitored optical device according to claim 1, wherein the optical device and the plurality of micro-resonator structures are formed on a single semiconductor substrate.

3. A monitored optical device according to claim 2, wherein each of the plurality of micro-resonators is a micro-cylinder having a respectively different circumference.

4. A monitored optical device according to claim 3, wherein the each of the plurality of micro-resonators is positioned with respect to the optical waveguide so that light propagating through the waveguide is received by the micro-resonator via evanescent coupling.

5. A monitored optical device according to claim 4, wherein each of the waveguide and the plurality of micro-resonators has a respective refractive index and the device further includes a cladding material positioned between the waveguide and the micro-resonators, the cladding material having an refractive index less than the refractive index of the waveguide and any of the micro-resonators.

6. A monitored optical device according to claim 1, wherein each of the plurality of micro-resonators is physically coupled to the waveguide so that light propagating through the waveguide is received by the micro-resonators through leaky-mode coupling.

7. A monitored optical device according to claim 1, wherein each of the plurality of micro-resonators includes a quantum well structure and at least one electrical contact for sensing a photocurrent induced by light from the waveguide that is received by the micro-resonator.

8. A monitored optical device according to claim 7, further including circuitry for applying a bias signal to the at least one electrical contact of at least one of the plurality of micro-resonators to cause the at least one micro-resonator to resonate at a different wavelength.

9. A monitored optical device according to claim 1, wherein each of the plurality of micro-resonators includes a bulk semiconductor material and at least one electrical contact for sensing a change in conductivity of the bulk semiconductor material in response to light from the waveguide that is received by the at least one micro-resonator.

10. A monitored optical device according to claim 1, wherein each of the plurality of micro-resonators is optically coupled to a respective photodetector that provides an electrical signal in response to light from the waveguide that is received by the respective micro-resonator.

11. A monitored optical device according to claim 1, further including means, for measuring an amount of optical power propagating through the waveguide to provide a power level signal.

12. A monitored optical device according to claim 11, wherein the means for measuring comprises a micro-structure, having a resonant length less than any wavelength of light that is transmitted through the waveguide.

13. A monitored optical device according to claim 12, wherein the micro-structure is positioned with respect to the waveguide so that light propagating through the waveguide is received by the micro-structure via evanescent coupling.

14. A monitored optical device according to claim 12, wherein the micro-structure is physically coupled to the waveguide so that light propagating through the waveguide is received by the micro-structure through leaky-mode coupling.

15. A monitored optical device according to claim 11, wherein the means for measuring includes a quantum well structure and at least one electrical contact for sensing a photocurrent induced by light from the waveguide that is received by the means for measuring.

16. A monitored optical device according to claim 11, wherein the means for measuring is optically coupled to a photodetector that provides an electrical signal in response to light from the waveguide that is received by the means for measuring.

17. A monitored optical device according to claim 11, wherein the means for measuring includes a bulk semiconductor material and at least one electrical contact for sensing a change in conductivity of the bulk semiconductor material in response to light from the waveguide that is received by the means for measuring.

18. A monitored optical device according to claim 11, wherein the means for measuring comprises a micro-structure having a plurality of resonant modes such that light having wavelengths in a range of interest for the monitored optical device resonates in the micro-structure.

19. A tunable semiconductor laser system comprising:

a semiconductor laser, formed on a semiconductor substrate, including an optical gain medium having an index of refraction and an optical path length, the laser producing laser light at a predetermined wavelength;

tuning means, coupled to the substrate and responsive to a tuning signal to adjust one of the index of refraction and the optical path length of the optical gain medium to change the predetermined wavelength of the laser light;

a micro-resonator structure formed on the semiconductor substrate and optically coupled to the optical gain medium and including an optical sensor configured to provide an electrical output signal, wherein the micro-resonator is configured to resonate when light at a predetermined wavelength propagates through the optical gain medium and to provide the electrical output signal having a peak value in response to light at the predetermined wavelength; and

control circuitry coupled the micro-resonator and to the tuning means for providing the tuning signal in response to the output signal of the micro-resonator structure.

20. A tunable semiconductor laser system according to claim 19, wherein the micro-resonator is a micro-cylinder.

21. A tunable semiconductor laser system according to claim 19, wherein the micro-resonator is positioned with respect to the optical gain medium so that light propagating through the optical gain medium is received by the micro-resonator via evanescent coupling.

22. A tunable semiconductor laser system according to claim 21, wherein each of the optical gain medium and the micro-resonator has a refractive index and the device further includes a cladding material positioned between the optical gain medium and the micro-resonator, the cladding material having an refractive index less than the refractive index of both the optical gain medium and the micro-resonator.

23. A tunable semiconductor laser system according to claim 19, wherein the micro-resonator is physically coupled to the optical gain medium so that light propagating through the optical gain medium is received by the micro-resonator through leaky-mode coupling.

24. A tunable semiconductor laser system according to claim 19, further including circuitry for applying a bias signal to the micro-resonator to cause the micro-resonator to resonate at a different wavelength.

25. A tunable semiconductor laser system according to claim 19, further including means, for measuring an amount of optical power propagating through the optical gain medium to provide a power level signal.

26. A tunable semiconductor laser system according to claim 25, wherein the means for measuring comprises a micro-structure, having a resonant length less than any wavelength of light that propagates through the optical gain medium.

27. A tunable semiconductor laser system according to claim 26, wherein the micro-structure is positioned with respect to the optical gain medium so that light propagating through the optical gain medium is received by the micro-structure via evanescent coupling.

28. A tunable semiconductor laser according to claim 26, wherein the micro-structure is physically coupled to the optical gain medium so that light propagating through the optical gain medium is received by the micro-structure through leaky-mode coupling.

29. A tunable semiconductor laser according to claim 25, wherein the means for measuring comprises a micro-structure having a plurality of resonant modes such that light having wavelengths in a range of interest for the tunable semiconductor laser resonates in the micro-structure.