The I-P curve was measured again, but this time in a lower current range of 1.0-1.9 [A].
The plot below is the latest I-P curve.
Based on the measurement and some thoughts, I decided to run this laser at about 1.8 [A] which gives us a middle power of ~ 360 [mW].
In the 40m history, the laser had been driven at 2.4 [A] in years of approximately 2006-2009, so it's possible to run it at such a high power,
but on the other hand Steve suggested to run it with a smaller power such that the laser power doesn't degrade so fast.
The laser controller handed from PK (#4855) was used in this measurement.
The nominal current was tuned to be 1.8 [A] by tuning a potentiometer on the laser head (see page.18 on the manual of LWE).
There was a huge bump around 1.4 [A] and sudden power drop at 1.48 [A] although I don't know the reason.
The old days the NPRO ( inside the MOPA ) was running ~1.7A 500 mW