I'm using a fiber optic bundle as a 2d displacement sensor to measure a small displacement. The bundle contains 40 000 micro fibers and those fibers are glued inside the bundle but not fused. That leads to a multiple dead zone between fibers. In order to improve the active surface of the bundle, we want to fuse the optical fibers at high temperature ( industrial process) but I want to know before performing this operation how can I estimate the impact of coupling between optical fibers when they are fused at high temperature , knowing that we use a borocylicate fibers with a 50 µm core diameter and a clading of 5µm only.
Using a Optical Backscatter Reflectometer (OBR)
http://lunainc.com/obr4600
The core and cladding diameters will remain mostly the same after fusing the fiber, so I don't expect much impact in the performance of the bundle. Slight core deformation can occur, but this should not affect the light guidance as well. Fusing the bundle will fill the air gap, but I am not sure the dead zones will still be significantly reduced.
Good luck with your experiment.
You're asking what is coupling ratio between conventional glass step index multicore fiber, right? You should see coupled modes theory. It seems like you have fibers with many modes but what really matters is geometry after fusion. It depend on bundle tapering, temperature and time which cause different degrees of diffusion etc. Look here:
https://www.researchgate.net/profile/Sergey_Babin/publication/5692480_Mechanism_of_mode_coupling_in_multicore_fiber_lasers/links/0fcfd51072f8d3f891000000
Article Mechanism of mode coupling in multicore fiber lasers
@ Bertrand Morasse : Do you mean that the 4 µm cladding fiber will not be affected when fusing the bundle at high temperature ?
In fact our goal is to increase the ratio of the surface occupied by the core fibers compared to the total surface of the detector which contains a multiple dead zones. This ratio is about 0.52 in our first bundle prototype and we think we could improve it by fusing the fibers on the next prototype. More detailed are presented on this article
http://iopscience.iop.org/0957-0233/26/1/015201
Cordially
To answer your last question, some dopant diffusion can occur, but I would not expect it to be significant (less than 1 um).
- Badges
- Science topic