Fiber Optics

Hello all,

Is it possible to use a fiber to improve the beam specs of something? Say, turn a 445nm multimode or a 635nm multimode into a single mode output or something closer to a single mode output? I know I need something to focus the original laser beam into to the laser fiber and something to collimate it at the other end.

Thanks!

Interesting thought.

I might bring some optic fibre home from work and put a multimode into it and see what happens. I know the multimode fibre we have is good for 635nm not sure about 445 though.

I'm certainly not an expert, but i know the beam gets reflected off the sides of the fibre multiple times so not sure if it would work or not. Best demonstration I've seen of it is on the Aixiz ebay site with their acrylic light pipes (although fibre is more complicated than this)

Well Fiber Optic Cable Supplier, Distributor - Fiber Optics For Sale Co. this place has a lot of fiber and accessories. I just don't know which one to pick lol. I e-mailed them but they haven't replied yet...

I think Edmund optics has some fiber for fiber coupled lasers...

I have heaps of 62 micron multimode patch leads at work... We use them on the digital consoles (you can feed 64 mono or 32 stereo audio channels through a fibre using AES over MADI). I have both SC and MT-RJ patch leads. The MT-RJ are dual (two fibres) and the SC are single fibre (two connectors for full duplex).

The will definately pass red and white light. One station we have a 55m run of cable and we used a white LED torch to figure out which fibre was which at the other end. The LED's in them look pale red like a 740 or 808 nm laser looks.

I think single mode fibre may be better though looking at this

For the hobbyist's purpose, multimode fiber is fine, and can be easily found. I am more curious about the various cheap but "good 'nuff" methods of terminating. I'm thinking perhaps the only way is with those gel crimps :undecided:

Basic idea is focus laser down to a spot smaller than the fiber face (and so that all light is coming within its cone of acceptance), and then use aspheric collimating lens to project image of the round fiber.

I thought it was neat that you can shine a flashlight into the side of an unshielded patch fiber and see light come out the ends.

Also, the no-polish gel crimp thingys are cool, should have been thought of a long time ago, though.

My telecoms guy gave me some fiber scraps to play with, a 3-pair cable mm, ~80um diameter

Don't multimode fibers give a non TEM00 output? Or is the effect not very noticeable? However, the core of the fiber is very small so I guess it may be hard to focus to a 1um point>...

I don't know, that's why I've been trying to find someone to give me fiber scraps to play with Logically, the aspheric would simply project an image of the fiber face, which I assume is round.

Of course, you can have all the toys in the world, but not having time to play with them is just as bad. Like I said, I want to find a good way of polishing, or at least getting a nice cleave, cheaply. Probably gonna just get prepolished gel tips.

I e-mailed Thorlabs about what type of fiber to use lol. They haven't responded yet though...

BShanahan14rulz said:

I don't know, that's why I've been trying to find someone to give me fiber scraps to play with Logically, the aspheric would simply project an image of the fiber face, which I assume is round.

Of course, you can have all the toys in the world, but not having time to play with them is just as bad. Like I said, I want to find a good way of polishing, or at least getting a nice cleave, cheaply. Probably gonna just get prepolished gel tips.

Click to expand...

Cheapest cleaver I've seen is this...

Siecor FBC-006 High Precision Fiber Optic Cleaver /Cutter | eBay

I bought some fiber patch leads home tonight and had a play...

I bought home a 1m long dual MT-RJ patch lead and 12 foot long SC patch lead (shown below:

MTRJ:



SC:



I fed the lowest power setting (probably around 200mW) from my 1W 637nm red down it and tried to focus the beam onto the fiber- it was hard keeping it focused as the beam and fiber were very small as in below:


The bean was TINY close to the fibre and spread very quickly, but it was a perfect circle. I didn't have enough hands to do this properly but initial results were promising. The last is using the MTRJ lead:





Then I tried 1.5 watts of 445nm. I couldn't do it with glasses on as I couldn't see the beam. It was bad enough having the whole room lit up blue and I dared not focus the beam on the fiber as I was sure I would melt it. You can clearly see how the beam disperses as it leaves the fibre. It certainly seems like its bouncing around inside the fibre and coming out in colimated beam.
Results below:



I will have more of a play when I have more time and when I can rig up a jig to focus it with.

Andrew

Apocalypse said:

Well Fiber Optic Cable Supplier, Distributor - Fiber Optics For Sale Co. this place has a lot of fiber and accessories. I just don't know which one to pick lol. I e-mailed them but they haven't replied yet...

Click to expand...

I can get fibre patch leads through work reasonably cheaply. I can't remember how much they cost but I think it was about $10-$20 for a metre. I can find out if you like?

The advantage of the patch leads is they are already terminated at both ends and are supposed to butt up against a diode. The patch panels just position two fibres very close to eachother.

And yes I know I'm alternating between English and American spelling of Fibre / Fiber!

AUS said:

I can get fibre patch leads through work reasonably cheaply. I can't remember how much they cost but I think it was about $10-$20 for a metre. I can find out if you like?

The advantage of the patch leads is they are already terminated at both ends and are supposed to butt up against a diode. The patch panels just position two fibres very close to eachother.

And yes I know I'm alternating between English and American spelling of Fibre / Fiber!

Click to expand...

It seems to work for both multimode diodes. The output is very nice at TEM00. Great work and awesome pics! The hard part would be focusing the output team to infinity though. Do you have lenses that can do that? Also, it'd be awesome if you could get some fiber for me. Could you also get a hold of the output lenses also?

Also about the fiber and fibre thing, my computer is set to Canadian spelling so every time I type fiber on word it tries to correct me lol xD

bobhaha said:

Cheapest cleaver I've seen is this...

Siecor FBC-006 High Precision Fiber Optic Cleaver /Cutter | eBay

Click to expand...

bobhaha, you have a few cheaper HERE, HERE, HERE and HERE, to name just a few examples :beer:

Well to be honest I haven't really looked that hard. Thanks though!

Yes, you can make the beam rounder, but you lose most of the power. You might as well use a single mode diode.

TOSLINK:





And lower power to see the shape better:


This is REALLY wide fiber though - about 1mm.