Method and system for avoiding package induced failure in swept semiconductor source
View Patent ↗Dry oxygen, dry air, or other gases such as ozone are hermetically sealed within the package of the external cavity laser or ASE swept source to avoid packaging-induced failure or PLF. PIF due to hydrocarbon breakdown at optical interfaces with high power densities is believed to occur at the SLED and/or SOA facets as well as the tunable Fabry-Perot reflector/filter elements and/or output fiber. Because the laser is an external cavity tunable laser and the configuration of the ASE swept sources, the power output can be low while the internal power at surfaces can be high leading to PIF at output powers much lower than the 50 mW.
1. A method for configuring an optical coherence tomography system, comprising
providing a swept source that includes a hermetic package, an optical bench within the hermetic package, a semiconductor gain chip installed on the optical bench for generating light, and a tunable filter installed on the bench for filtering the light from the semiconductor gain chip to generate a swept optical signal;
filling the hermetic package with an atmosphere that contains oxygen;
generating a swept optical signal with the swept source; and
transmitting the swept optical signal to an interferometer.
2. A method as claimed in claim 1 , wherein the atmosphere within the hermetic package contains at least 10% oxygen.
3. A method as claimed in claim 1 , further comprising including a getter in the hermetic package.
4. A method as claimed in claim 3 , wherein the getter captures moisture.
5. A method as claimed in claim 3 , wherein the getter captures hydrogen or hydrocarbons.
6. A method as claimed in claim 3 , wherein the getter is in the form of pellets.
7. A method as claimed in claim 3 , further comprising applying the getter to a lid of the hermetic package.
8. A method as claimed in claim 1 , wherein the semiconductor gain chip is a VCSEL chip.
9. A method as claimed in claim 8 , wherein the tunable filter is integrated with the VCSEL chip.
10. A method as claimed in claim 1 , wherein the semiconductor gain chip and the filter are parts of a laser cavity.
11. A method as claimed in claim 1 , wherein the swept source is a non-laser swept source and the semiconductor gain chip is a broadband source.
12. A method as claimed in claim 1 , further comprising ozone cleaning the hermetic package prior to lid sealing.
13. A method as claimed in claim 1 , wherein the atmosphere within the hermetic package contains 10-50% oxygen.
14. A method as claimed in claim 1 , wherein the hermetic package is filled with dry oxygen.
15. A method as claimed in claim 1 , wherein the hermetic package is filled with ozone.
16. A method as claimed in claim 1 , wherein the swept source tunes the swept optical signal over a wavelength range of about 970-1100 nm.
17. A method as claimed in claim 1 , wherein the semiconductor gain chip is an edge-emitting semiconductor gain chip that is paired with a micro-electro-mechanical Fabry-Perot tunable filter.