After the work done on the neoVAN fiber we notice a power reduction of ~ 2 W at the neoVAN output. This is visible on plot 1, blue curve: PSL_AMP_DC signal (see plot 2 for the associated legend)
We notice a large neoVAN beam alignement drift around the operations on the fibers. Visible on the plot 3: this is the differential between the neoVAN beam profile before and after the fiber operation. We notice 126 um beam drift
A possible explanation could be that the fiber were put back in place in their SMA sockets with a possible residual twist angle (few degrees) which could impact the orientation of the fiber outptut axis wrt the neoVAN crystal. Although we would have considered this as a very small effect.
Preliminary Conclusion:
- the fiber does impact on the neoVAN optical axis
- the 2 W power lost could be recovered with a proper alignement of the seeder (optical axis of the seeder was kept untouched while the optical axis of the neoVAN was not)