posted Aug 23, 2013, 10:32 AM by Tiberius Brastaviceanu
updated Aug 23, 2013, 10:34 AM
Recently, Hang Qu used Zemax to simulate the fiber bending sensor based on a regular multimode fiber. Here are some of his conclusions:
- Zemax is capable to simulate the bending sensing based on a regular multimode fiber, optimize the optical configuration of the fiber sensor setup (collimating light sources, optimizing coupling efficiency of fiber), calculate the transmission or reflection intensity of fiber in response to bending.
- In the simulation, the mirror can be either coated on the end of fiber, or you can also use external mirror which put in the vicinity of the fiber free end.
- in the simulation, the fiber tip can be cleaved vertical to the fiber axis, or with an angle tilted to fiber axis.
- Zemax can not directly simulate the fiber with scratches, however, one can instead add an absorption layer coated on the core of the fiber to simulate these scratches.
- Zemax can calculate the coupling efficiency of single mode fiber or fiber taper, but have difficulties in simulating the transmission or reflection intensities of single mode fiber or tapered fiber. Because zemax operates by ray tracing, when the core size is large (e.g. multimode fiber), you can approximate use ray tracing and total internal reflection principle to simulate the guidance of fiber. However, when the core size is small (e.g. single mode fiber), you have to use modal analysis to calculate the behavior of fiber. Therefore, for bending sensor based on tapered fiber, I think comsol (3D simulation) would be a better option.
The attachment is some figures for the simulation of the bending multimode fiber with the fiber tip coated with a mirror. If you guys want to use Zemax in you simulation in the future, I am willing to share my opinions.