Bandwidth optimization of PVDF clad GI-POF

The PVDF clad GI-POF has a flat refractive index region in the core that can cause large modal dispersion. On the other hand, for practical use in high speed optical link, it is assumed to use Under-filled launch (UFL) that launches only small mode groups in the GI core region by adapting an LD as a light source. We investigated the way to reduce the mode coupling (the energy transfer among the propagating modes) and to achieve the high bandwidth property in a PVDF clad GI-POF. It was found that the mode coupling strength could be reduced by increasing the numerical aperture (NA) of the GI region in the PVDF clad GI-POF, and the PVDF clad GI-POF with high bandwidth under UFL condition could be fabricated for the first time by decreasing the mode coupling.