Kicking the habit/semiconductor lasers without isolators
Abstract
In this paper, we propose and demonstrate a solution to the problem of coherence degradation and collapse caused by the back reflection of laser power into the laser resonator. The problem is most onerous in semiconductor lasers (SCLs), which are normally coupled to optical fibers, and results in the fact that practically every commercial SCL has appended to it a Faraday-effect isolator that blocks most of the reflected optical power preventing it from entering the laser resonator. The isolator assembly is many times greater in volume and cost than the SCL itself. This problem has resisted a practical and economic solution despite decades of effort and remains the main obstacle to the emergence of a CMOS-compatible photonic integrated circuit technology. A simple solution to the problem is thus of major economic and technological importance. We propose a strategy aimed at weaning semiconductor lasers from their dependence on external isolators. Lasers with large internal Q-factors can tolerate large reflections, limited only by the achievable Q values, without coherence collapse. A laser design is demonstrated on the heterogeneous Si/III-V platform that can withstand 25 dB higher reflected power compared to commercial DFB lasers. Larger values of internal Qs, achievable by employing resonator material of lower losses and improved optical design, should further increase the isolation margin and thus obviate the need for isolators altogether.
Additional Information
© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. Received 6 Oct 2020; revised 6 Nov 2020; accepted 7 Nov 2020; published 16 Nov 2020. Funding: Defense Advanced Research Projects Agency (N66001-14-1-4062); Army Research Office (W911NF-14-P-0020, W911NF-15-1-0584, W911NF-16-C-0026). The authors declare no conflicts of interest.Attached Files
Published - oe-28-24-36466.pdf
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Additional details
- Eprint ID
- 107181
- Resolver ID
- CaltechAUTHORS:20201217-160839807
- Defense Advanced Research Projects Agency (DARPA)
- N66001-14-1-4062
- Army Research Office (ARO)
- W911NF-14-P-0020
- Army Research Office (ARO)
- W911NF-15-1-0584
- Army Research Office (ARO)
- W911NF-16-C-0026
- Created
-
2020-12-18Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field