Stabilized multimode fiber link using graded-index plastic optical fiber with strong mode coupling

We demonstrate that a multimode fiber (MMF) link based on a vertical surface emitting laser (VCSEL) can be stabilized using a graded-index plastic optical fiber (GI POF) with strong mode coupling. In the MMF link with strong optical feedbacks to the VCSEL, the GI POF allows for higher quality data transmission with less noises and instabilities than silica GI MMFs. By directly observing beams backreflected to the VCSEL, we show that the transmission quality improvement is closely related to random mode coupling because of light scattering by microscopic heterogeneities in the GI POF core. These results suggest that the low-noise GI POF allows for the low-cost optical interconnects without optical isolators, angled fiber endfaces, and precise alignments for consumer applications.