Scale Effect of a Fluorescent Waveguide in Organic Micromaterials: A Case Study Based on Coumarin Microfibers

The
classical method for evaluating the waveguide ability only
focuses on the optical loss coefficient. However, for the micro- or
submicroscale, an organic waveguide is demonstrated by the present
study whose scale effect should not be neglected. We found that the
optical loss coefficient increased remarkably when decreasing the
sectional size of the microfibers. Furthermore, simulations based
on Finite-Difference Time-Domain also demonstrated the size-dependent
effect of the waveguide. Both the experimental and simulating results
showed that the optical loss coefficient converges to a certain value,
which means that the scale effect can be neglected as the sectional
size is large enough. On the basis of the present study, we suggest
that the scale-dependent effect on the sectional size of the waveguide
should be investigated by evaluating the waveguide ability by the
optical loss coefficient.