20W pulsed IR fiber laser fiber severed

[baltersice]

Hi, Electronics Experts!
I've set foot on some new terrain recently ...
I am always surprised by your universal knowledge, so I thought I'd post this here and hope for some input, in spite of it not being electronics

https://imgur.com/a/G5l5SpT

I got a ~20W fiber laser by SPI Lasers, UK. Someone snipped off the fiber to save a few minutes in the disassembly of some larger bit of kit.

I'd like to try and fix that, but my experience is limited and I'd like to hear a few opinions before messing things up even more.

I don't think there is an internal coupling anywhere - the fiber probably goes from the guts of the laser all the way out through the armored cable to the termination. So I think I have to do some splicing. Will that work for such a <500kHz 20W IR pulsed laser? Or will a splice in that fiber cause a lot of chaos and internal reflections n stuff?

I have an older Sumitomo 36 fusion splicer and some crappy Chinese cleaver. I've attacked the fiber with a scalpel and was able to scratch off some cladding easily, so I think it is a polymer cladding that I can remove with acetone.

The cladding outside diameter is 300 µm, I don't know what the core diameter is yet, but it's probably a bit more girthy than an average telecoms fiber for which the Sumitomo splicer was designed? It should probably be able to handle that anyway I expect?

I've purchased some FT200EMT to practice before messing around with the important fiber.

But to progress in the disassembly (to flip out the top level) I have to release some length of fiber from that slanted spool in the last photo. And I am a bit scared of that ... does anybody know why that slanted spool is there and why it's different from the loosy goosy arrangement next to it? It feels important and easy to mess up ...