Integrated optical coherence tomography systems and methods
Disclosed herein are optical integration technologies, designs, systems and methods directed toward Optical Coherence Tomography (OCT) and other interferometric optical sensor, ranging, and imaging systems wherein such systems, methods and structures employ tunable optical sources, coherent detection and other structures on a single or multichip monolithic integration. In contrast to contemporary, prior-art OCT systems and structures that employ simple, miniature optical bench technology using small optical components positioned on a substrate, systems and methods according to the present disclosure employ one or more photonic integrated circuits (PICs), use swept-source techniques, and employ a widely tunable optical source(s).
1. An optical system for optical coherence tomography comprising:
interferometer circuitry configured to divide a tunable optical signal between a reference path and a sample path and to combine optical signals returning from the reference path and the sample path to generate an interference signal, said interferometer circuitry including dual-polarization, dual-balanced, in-phase and quadrature (I/Q) detection outputs;
a detection system comprising at least one photodetector coupled to the interferometer circuitry; and
a tunable optical source configured to generate the tunable optical signal;
wherein the interferometer circuitry and the tunable optical source are integrated onto a photonic integrated circuit (PIC).
2. The optical system of claim 1 further comprising a k-clock module configured to generate a k-clock signal for triggering the detection system, wherein said k-clock module is integrated onto the PIC.
3. The optical system of claim 1 wherein said tunable optical source includes one or more optical frequency modulators.
4. The optical system of claim 1 wherein said tunable optical source includes one or more tunable optical filters.
5. The optical system of claim 1 further comprising one or more surface grating couplers integrated onto the PIC and configured to couple light between the PIC and one or more optical fibers.
6. The optical system of claim 1 further comprising one or more facet couplers integrated onto the PIC and configured to couple light between the PIC and one or more optical fibers.
7. The optical system of claim 1 further comprising a non-silicon optical gain element in optical communication with the PIC, wherein the PIC is a silicon photonic PIC.
8. The optical system of claim 1 wherein the PIC includes a plurality of optical ports, and wherein each one of said plurality of optical ports is coupled to an optical fiber, and each one of said optical fibers is included in a single block affixed to the PIC.
9. The optical system of claim 1 further comprising a carrier substrate onto which is mounted the PIC and one or more additional electrical chips.
10. The optical system of claim 1 further comprising an optical gain element integrated onto the PIC, the optical gain element having a gain response that is wavelength-dependent.
11. The optical system of claim 1 further comprising a modulator integrated onto the PIC, said modulator positioned in an optical path of the tunable optical signal.
12. The optical system of claim 1 , further comprising processor circuitry configured to process the interference signal to determine information about a longitudinal reflectivity profile of optical properties of a sample positioned in the sample path.
13. The optical system of claim 1 , wherein the detection system is integrated on the PIC.
14. An electro-optical system comprising:
one or more couplers configured to optically couple light comprising a tunable optical signal into one or more photonic integrated circuits (PICs);
interferometer circuitry configured to divide the tunable optical signal between a reference path and a sample path and to combine optical signals returning from the reference path and the sample path to generate an interference signal; and
a detection system configured to detect the interference signal,
wherein the interferometer circuitry, one or more couplers and detection system are all integrated onto the one or more photonic integrated circuits (PICs) and commonly packaged or positioned on a common substrate.
15. The system of claim 14 where the interferometer circuitry comprises dual-balanced, in-phase and quadrature detection outputs and the detection system comprises integrated photodetectors.
16. The system of claim 14 where the interferometer circuitry comprises dual polarization, dual-balanced, in-phase and quadrature outputs and the detection system comprises integrated photodetectors.
17. The system of claim 16 further comprising a tunable optical source configured to generate the tunable optical signal and a k-clock module configured to generate a k-clock signal for triggering the detection system, wherein the k-clock module, the interferometer circuitry, the tunable optical source and the detection system are all integrated onto the one or more photonic integrated circuits (PICs).
18. The system of claim 14 , further comprising processing circuitry configured to process the interference signal to determine a ranging or longitudinal reflectance image of a sample positioned in the sample path of the interferometer circuitry.