Fibre coupling a large frame ion // advice?

[danielbriggs]

Hi chaps,
I have something very similar to a large frame ion, in terms of beam quality and output power, and wanted to ask the experts // people with direct experience of doing this, how best to fibre couple such a beam? Planned delivery will be to a remote scan head (20-50m away).

In the past I've coupled a 10W OPSL 532nm before with 50µm with a 5-axis launcher, with correct peaking-procedure, and wasn't impressed with the coupling efficiency.

Does anyone have any recommendations for such quality beams, M^2 <1.4, Po = ~30W, specifically w.r.t. what diameter fibres, and coupling / decoupling lenses?
Is there any possibility to deliver the output and maintain very close to the input beam spec at high efficiencies (>70%)? Dia 2mm, 0.8mRad?

Thanks!
Dan

[planters]

It's my understanding that if you do not use single mode fiber then there will be a loss in beam quality as the beam enters and exits the fiber. I believe that is how fiber helps to homogenize a diode used as a pump source. Other than remaining within the acceptance angle of the fiber with the NA of the launching lens and at these FL probably using aspherical lenses, I can not give any hands on advise. Good luck.

[danielbriggs]

I'm not sure I can couple many watts into SM fibre (<10µm)... I think something may burn

[planters]

I know. Maybe its not practical, but I would certainly eliminate the possibility of free space through a beam tube.

[Draco]

quick question, that has me thinking of a 20+ watt fiber coupled diode bar, i want to get that back into a beam and am told that the lends is not critical, I have a spare double convex lens that would have been used in a green dpss, would this work? the diode is 850nm or something like that

[andy_con]

you could just put a donk on it briggs

[VDX]

... I have a Coherent-diode with 25W@808nm, where they positioned 19 fibers to every of the emitters in the bar and bundled them to an 'output' of 0.7mm diameter - not so easy to get this output into a SM fiber :-/

Other 25W@975nm diodes from IPG are better assembled - here three single 9W emitters are collimated and combined and focussed into a 105µ-fiber, what's much better usable than the 700 microns from Coherent ... but too, hard to fit into a 10 microns fiber ...

Viktor

[mixedgas]

15 mm diameter 13.7 mm focal length into 100 um or greater core.
Achromat required for multiline
single element preferred for ultra high power Qswitched.

Steve

[danielbriggs]

Thanks Steve; much appreciated.

[andy_con]

Oh no thanks to me then