Tips for working with optical fiber?

April 3, 2008 11:09 AM

Tips for working with optical fibers (stripping, cleaving, aligning, etc.)?

I'll soon start working with an infrared laser and optical fibers as part of my research. Unfortunately, my lab colleagues don't have much experience in this area. Can you recommend any books or websites that would have useful tips on operational details such as stripping, cleaving, and aligning? Really, any tricks of the trade would be appreciated.

(Regarding safety: I'll have the safety folks approve any setup before I start working with it. This is a 1W 1064nm laser accompanied by a visible guide laser, output from an uncollimated single-mode fiber, and it will be used inside an enclosure in a light-tight room by an operator wearing OD 5 eye protection.)

posted by Mapes to science & nature (3 comments total)

ObGoogle
posted by rhizome at 11:18 AM on April 3

I did some menial fibre assembly work a while back (plastic fibre, for data). Not sure if this is any help, but the system they had there was based on putting a plug on each end of the fibre, so it could be easily slotted (and unslotted) from sockets, and those connectors would ensure the fibre was aligned with the receiver or emitter.

- First step was a standard wire-stripping tool with an appropriate guage hole, which would pull the insulation off the end without nicking the fibre.
- Slot the fibre into a plug. Use a crimping tool to make the plug permanent. The fibre would slide in and about halfway inside it, the hole would narrow, so that only un-insulated fibre could go the rest of the way. The idea was strip enough insulation that a small amount of fibre would poke out the end.
- Next step was a clipboard with two grades of sandpaper on it, and a block with a hole drilled in it perpendicular to the face (ie just drilled via drill-press). The hole was the diametre of the plug, so by putting the plug in the block, then running the block+fibre over the sandpaper, the block would ensure that the end of the fibre was sanded square-on with the plug.
- Sand it on the rough sandpaper first to square off the fibre and level it down to the start of the plug. You can tell it's level when the plastic dust left on the sandpaper changes colour as the plug plastic starts to get sanded in addition to the fibre. Then move the block on to the fine sandpaper to polish the end for light transmission.
- Done.
posted by -harlequin- at 11:43 AM on April 3

I've never had to work with fiber stripping, cleaving, etc - I've always bought connectorized fiber, but I've done some alignment of fiber launches. It's a pain, but with a visible guide laser shouldn't be too bad.

First, get a good single mode fiber mount. Then the real trick is to get the fiber roughly aligned so that enough light comes out the other end that you can see it. Once you've done that you then start scanning each adjustment on the fiber launch to maximize the power that comes out the other end. You'll want a decent power meter for this. The challenge with this whole process is that the fiber is only a few microns in diameter and you need to be very close in alignment both in X and Y but also in angle.

Newport has a good tutorial on fibers.
posted by pombe at 4:34 PM on April 3