Microresonator-frequency-comb-based platform for clinical high-resolution optical coherence tomography

1. A method of providing optical coherence tomography (OCT) imaging, the method comprising:

using as an imaging source an on-chip frequency comb source interfaced, by a circulator, with an OCT system, wherein the frequency comb source comprises a silicon nitride based ultra high-Q resonator pumped by a pump signal from a laser and tuned to control a resonance of the resonator relative to a frequency of the pump signal, wherein the ultra high-Q resonator has a Q value in a range of from 8×10 5 to 3.7×10 7 ; and

reconstructing OCT images from resulting spectral data from target tissue illuminated by the imaging source.

2. The method of claim 1 , wherein reconstructing OCT images includes the steps of background subtraction, linear-k interpolation, apodization, dispersion compensation, and applying a Fourier transform to the resulting spectral data from the target tissue.

3. The method of claim 1 , wherein frequency combs of the frequency comb source comprise discrete lines with a frequency spacing determined by the geometry of the resonator.

4. The method of claim 1 , wherein frequency combs of the frequency comb source have a bandwidth of 110 nm at 30 dB and a line spacing of 38 GHz.

5. The method of claim 1 , wherein the on-chip frequency comb source comprises integrated micro-heaters on top of the resonator and configured to provide temperature tuning to control cavity resonance of said resonator.

6. The method of claim 1 , wherein the laser comprises a fixed wavelength pump laser.

7. The method of claim 1 , wherein the on-chip frequency comb source comprises an additional resonator pumped by the laser, wherein the additional resonator is disposed on a same chip as the resonator.

8. The method of claim 1 , wherein the on-chip frequency comb source comprises a waveguide configured to couple light from the laser to the resonator.

9. The method of claim 8 , wherein the waveguide comprises silicon nitride.

10. The method of claim 1 , wherein the laser comprises one of a distributed feedback (DFB) laser, external cavity laser, or Fabry-Perot laser.

11. The method of claim 1 , wherein an axial resolution of the OCT images is less than 5 μm.

12. The method of claim 1 , wherein a waveguide used to carry the pump signal to the resonator has a cross-sectional dimension that allows anomalous dispersion at the pump wavelength.

13. The method of claim 1 , wherein the resonator is tuned relative to the frequency of the pump signal such that the frequency comb is not locked in phase.

14. The method of claim 13 , wherein the resonator has a cross-sectional width of between 2000 nm to about 2200 nm.

15. The method of claim 13 , wherein the resonator has a cross-sectional width of between about 2150 nm to about 2200 nm.

16. The method of claim 13 , wherein the resonator has a waveguide structure with a parametric gain that enables ultra-broad optical bandwidth comprising at least an octave in bandwidth.

17. The method of claim 13 , wherein the resonator has as cavity length such that an axial resolution of the OCT system is below 1 μm.

18. The method of claim 1 , wherein the efficiency of the comb is in a range of about 20% to about 30%.

19. The method of claim 13 , wherein the ultra-high Q resonator has losses less than 3 dB/m.

20. A method of providing optical coherence tomography (OCT) imaging, the method comprising:

using as an imaging source an on-chip frequency comb source interfaced, by a circulator, with an OCT system, wherein the frequency comb source comprises a silicon nitride based ultra high-Q resonator pumped by a pump signal from a laser and tuned to control a resonance of the resonator relative to a frequency of the pump signal;

and reconstructing OCT images from resulting spectral data from target tissue illuminated by the imaging source.