Daniel, Nutsinee
Today we saw the most green transmission we haven't seen in awhile. As of today we are back to 18% transmission (we have been at 13% transmission since beginning of January). Here's a plot looking at OPO REFL when OPO was unlocked and totally off-resonance.
This bizarre behavior happened very suddenly, today morning at 8:14 local was the clearest turning point. The intensity servo tried to engage but hit the limit because the set point was too far off from the actual OPO refl power.
Looking at the OPO scan it seems like TEM10 has just disappeared compared to alog46474. We now have 83% mode matched (was 78% back in January).
It appears that we have a self-align OPO cavity. I'll take that.
This is rather starting to sound like SBS (speculated as so by B. Lantz on the SYS fiber call). Im not sure of another mechanism that could move the modes like this over such a short timeperiod. Possibly a 01 acoustic mode pulling energy out of the 00 and moving it slighly into 01, while generating a reverse propagating stokes 01??
If/when it goes back to the lossy state, can you look at the retro-reflection from the fiber from your power monitor pickoff mirror?