Timeline for Unexpected wavelength jumps in a laser observed: a fundamental noise source in VCSELs?
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| Apr 27, 2019 at 19:13 | comment | added | svilches | Let us continue this discussion in chat. | |
| Apr 27, 2019 at 18:41 | comment | added | The Photon | Also, given the fairly sparse details in the datasheet (Output power is 1 mW, but they don't even say how much forward current is needed to get that power) this vendor may not be entirely conservative about their specs. | |
| Apr 27, 2019 at 18:39 | comment | added | The Photon | "single mode" should mean a single transverse mode. I didn't catch that in the datasheet earlier. But, for example, if you're giving it more back-reflection than it's designed for, or driving it with more current than it's designed for, it might go multi-mode. Also, given the small effects you're seeing, it's possible that hops in the side-modes could be part of the effect. | |
| Apr 27, 2019 at 18:37 | comment | added | svilches | Very interesting, I assumed that "single mode VCSELs" would be single transversal and single longitudinal mode. So would it be possible that some of the 4-10 transversal modes are flipping polarization and effecting the overall wavelength? | |
| Apr 27, 2019 at 18:34 | comment | added | The Photon | To test whether you're getting polarization hops, put a polarizing filter in before your inteferometer (or better yet, use a spectrum analyzer/spectrometer). | |
| Apr 27, 2019 at 18:32 | comment | added | svilches | About polarization flips: I understand that they are binary (only two different modes) and that they happen only once at a very specific biasing point of the laser. In our measurements we observe multiple preferred wavelength steps (as seen in the plots in the original question) and they happen at multiple biasing currents. How could I confirm or reject this hypothesis? | |
| Apr 27, 2019 at 18:32 | comment | added | The Photon | @svilches, do you have an optical spectrum analyzer or spectrometer available? That would be the easiest way to tell. One possibility is that polarization hops cause much smaller frequency deviation than transverse mode hops. The other is that you have 4-10 modes operating (typical for the kind of laser you linked to in another comment), so when one of them hops it doesn't cause as big a change in your MZ interferometer output as it would if you had a single mode laser where all the output power hopped at the same time. | |
| Apr 27, 2019 at 18:28 | comment | added | svilches | I am suspecting of these transverse mode hops. Do you have an intuition about the spectral spacing of such jumps? This paper [doi 10.1109/3.985571] shows a spectral spacing of ~100 GHz between transverse modes, while I am observing ~50 MHz hops (3 orders of magnitude difference...) | |
| Apr 27, 2019 at 15:03 | history | answered | The Photon | CC BY-SA 4.0 |