Filtered ASE swept source for OCT medical imaging
View Patent ↗An integrated swept wavelength optical source uses a filtered ASE signal with an optical amplifier and tracking filter. This source comprises a micro optical bench, a source for generating broadband light, a first tunable Fabry Perot filter, installed on the bench, for spectrally filtering the broadband light from the broadband source to generate a narrowband tunable signal, an amplifier, installed on the bench, for amplifying the tunable signal, and a second tunable Fabry Perot filter, installed on the bench, for spectrally filtering the amplified tunable signal from the amplifier. A self-tracking arrangement is also possible where a single tunable filter both generates the narrowband signal and spectrally filters the amplified signal. In some examples, two-stage amplification is provided. The use of a single bench implementation yields a low cost high performance system. For example, polarization control between components is no longer necessary.
1. A wavelength swept optical source, comprising:
a micro optical bench;
a source for generating broadband light;
a first tunable Fabry Perot filter, installed on the bench, for spectrally filtering the broadband light from the broadband source to generate a tunable signal, wherein a full width half maximum bandwidth of the first Fabry-Perot tunable filter is less than 20 GHz;
an amplifier, installed on the bench, for amplifying the tunable signal;
at least one filter-amplifier lens, installed on the bench, for coupling the tunable signal from the first tunable Fabry Perot filter into the amplifier;
a second tunable Fabry Perot filter, installed on the bench, for spectrally filtering the amplified tunable signal from the amplifier; and
at least one amplifier-filter lens, installed on the bench, for coupling the tunable signal from the amplifier into the second tunable Fabry Perot filter;
wherein the amplifier is located on the bench optically between the first tunable Fabry-Perot filter and the second tunable Fabry-Perot filter.
2. A wavelength swept optical source as claimed in claim 1 , further comprising a hermetic package, the micro optical bench being installed within the hermetic package.
3. A wavelength swept optical source as claimed in claim 2 , wherein the hermetic package is a butterfly package.
4. A wavelength swept optical source as claimed in claim 1 , further comprising thermoelectric cooler attached to a backside of the optical bench to control a temperature of the optical bench.
5. A wavelength swept optical source as claimed in claim 1 , wherein the source comprises a superluminescent light emitting diode, which is installed on the bench.
6. A wavelength swept optical source as claimed in claim 1 , wherein the source comprises a semiconductor optical amplifier, which is installed on the bench.
7. A wavelength swept optical source as claimed in claim 1 , wherein the first tunable Fabry Perot filter and the second tunable Fabry Perot filter are operated in a reflective mode.
8. A wavelength swept optical source as claimed in claim 1 , wherein a full width half maximum bandwidth of the second Fabry-Perot tunable filter is at least 2 times broader in frequency than the bandwidth of the first Fabry-Perot tunable filter.
9. A wavelength swept optical source as claimed in claim 1 , wherein a full width half maximum bandwidth of the first Fabry-Perot tunable filter is about 10 GHz or less.
10. A wavelength swept optical source as claimed in claim 1 , wherein the amplifier is a semiconductor optical amplifier.
11. A wavelength swept optical source as claimed in claim 1 , further comprising a second amplifier for amplifying the amplified tunable signal from the second tunable Fabry Perot filter.
12. A wavelength swept optical source as claimed in claim 1 , further comprising an isolator between the first tunable Fabry Perot filter and the amplifier.
13. A wavelength swept optical source as claimed in claim 1 , further comprising an isolator between the amplifier and second tunable Fabry Perot filter.
14. An optical tomography system comprising:
a wavelength swept optical source, including: a micro optical bench, a source for generating broadband light, a tunable Fabry Perot filter, installed on the bench, for spectrally filtering the broadband light from the broadband source to generate a tunable signal, an amplifier, installed on the bench, for amplifying the tunable signal, and at least one filter-amplifier lens, installed on the bench, for coupling the tunable signal from the tunable Fabry Perot filter into the amplifier, wherein a full width half maximum bandwidth of the Fabry-Perot tunable filter is less than 20 GHz; and
an interferometer for transmitting the amplified tunable signals from the wavelength swept optical source to a sample and reference path and combining the optical signals from the sample and the reference path to generate an interference signal.
15. A system as claimed in claim 14 , wherein the wavelength swept optical source further includes a second amplifier, installed on the bench, for amplifying the amplified tunable signal from the amplifier.
16. A system as claimed in claim 14 , wherein the wavelength optical swept source further includes a second tunable Fabry Perot filter, installed on the bench, for spectrally filtering the amplified tunable signal from the amplifier.
17. A system as claimed in claim 14 , further comprising a hermetic package, the micro optical bench being installed within the hermetic package.
18. A system as claimed in claim 17 , wherein the hermetic package is a butterfly package.
19. A system as claimed in claim 14 , further comprising thermoelectric cooler attached to a backside of the optical bench to control a temperature of the optical bench.
20. A system as claimed in claim 14 , wherein the source comprises a superluminescent light emitting diode, which is installed on the bench.
21. A system as claimed in claim 14 , wherein the source comprises a semiconductor optical amplifier, which is installed on the bench.
22. A system as claimed in claim 14 , wherein the tunable Fabry Perot filter is a microelectromechanical filters.
23. A system as claimed in claim 16 , wherein a full width half maximum bandwidth of the second Fabry-Perot tunable filter is at least 2 times broader in frequency than the bandwidth of the first Fabry-Perot tunable filter.
24. A system as claimed in claim 14 , wherein a full width half maximum bandwidth of the first Fabry-Perot tunable filter is about 10 GHz or less.
25. A system as claimed in claim 14 , wherein the amplifier is a semiconductor optical amplifier.
26. A system as claimed in claim 14 , further comprising an isolator between the tunable Fabry Perot filter and the amplifier.