OCT medical imaging system using gain waveguide array swept source
View Patent ↗An optical coherence tomography system uses an optical source that comprises a series of gain waveguides that generate light at the frequencies at which the interference signal is to be sampled. In this way, the optical source generates a discretely tuned optical signal. This has the advantage that the tuning can be directly controlled by a controller that is also used to synchronize the sampling of the interference signal. This avoids the need for separate frequency clock synchronization. In embodiments, the gain waveguides are fabricated from one or more semiconductor edge emitting bars. In some implementations, the gain waveguides comprise periodic structures that define the frequency of operation of the waveguide. However in other implementations, the combiner comprises a dispersive element, such as a diffractive grating, that provides frequency specific feedback to each waveguide.
1. An optical coherence analysis system comprising:
a swept optical source including an array of gain waveguides that amplify light at different frequencies and a combiner that combines light from the gain waveguides into an optical signal;
an interferometer for dividing the optical signal between a reference arm and a sample arm leading to a sample; and
a detection system for detecting an interference signal generated from the optical signal from the reference arm and from the sample arm.
2. A system as claimed in claim 1 , wherein the gain waveguides are fabricated from one or more semiconductor edge emitting bars.
3. A system as claimed in claim 1 , wherein the gain waveguides comprise periodic structures that define the frequency of operation of the waveguide.
4. A system as claimed in claim 1 , wherein the combiner comprises a dispersive element that provides frequency specific feedback to each of the gain waveguides.
5. A system as claimed in claim 4 , wherein the dispersive element is a diffractive grating.
6. A system as claimed in claim 1 , wherein the combiner comprises at least one cylindrical lens.
7. A system as claimed in claim 1 , further comprising a switching system and a current source, wherein the switching system provides current from the current source sequentially to the gain waveguides.
8. A system as claimed in claim 7 , wherein the detection system comprises a data acquisition system that samples interference signal.
9. A system as claimed in claim 8 , further comprising a controller for synchronizing the switching system and the sampling by the data acquisition system.
10. A system as claimed in claim 1 , further comprising a switching system and an injection current source, wherein the switching system provides current from the injection current source sequentially to the gain waveguides as a ridge injection current.
11. An optical coherence analysis method comprising:
amplifying light at different frequencies using an array of gain waveguides;
combining the light from the gain waveguides into an optical signal;
dividing the optical signal between a reference arm of an interferometer and a sample arm of the interferometer, the sample arm leading to a sample; and
detecting an interference signal generated from the optical signal from the reference arm and from the sample arm.
12. A method as claimed in claim 11 , wherein the gain waveguides are fabricated from one or more semiconductor edge emitting bars.
13. A method as claimed in claim 11 , wherein the gain waveguides comprise periodic structures that define the frequency of operation of the waveguide.
14. A method as claimed in claim 11 , further comprising feedback back light into the gain waveguides with a dispersive element that provides frequency specific feedback.
15. A method as claimed in claim 14 , wherein the dispersive element is a diffractive grating.
16. A method as claimed in claim 11 , further comprising applying current from a current source sequentially to the gain waveguides.
17. A method as claimed in claim 11 , further comprising applying current from an injection current source sequentially to the gain waveguides as a ridge injection current.
18. A method as claimed in claim 11 , further comprising synchronizing the provision of the current to the different gain waveguides with sampling of the interference signal.
19. An optical coherence analysis system comprising:
a swept optical source including an array of gain waveguides that amplify light at different frequencies and a combiner that combines light from the gain waveguides into an optical signal;
an interferometer for dividing the optical signal between a reference arm and a sample arm leading to a sample;
a detection system for detecting an interference signal generated from the optical signal from the reference arm and from the sample arm;
a switching system and a current source, wherein the switching system provides current from the current source sequentially to the gain waveguides; and
a controller for synchronizing the switching system and the sampling by the data acquisition system.