Significantly improved frequency response by low-noise graded-index plastic optical fiber (Conference Presentation)

Abstract

The growing demand for high-speed data transmission in consumer applications such as 4K/8K television motivates the development of multilevel modulation. Multilevel modulation can increase bit rate over 2-level modulation for same symbol rate, but is subject to noise and modulation instability in optical link. Recently, we experimentally demonstrated that a graded-index plastic optical fiber (GI POF) significantly improved the transmission signal quality compared with a silica GI multimode fiber (MMF) in the consumer-friendly MMF link without an optical isolator, where laser and optical fiber easily coupled. This high-quality transmission is related to reflection noise reduction because of a strong mode coupling in the GI POF. However, the signal quality also depends on the modulation response of the vertical-cavity surface-emitting laser (VCSEL) coupled with optical fibers. Here, we investigate the influence of the strong mode coupling in the low-noise GI POF on the modulation response of the VCSEL in the consumer-friendly MMF link. We show that the low-noise GI POF can significantly decrease the distortion of the modulation response compared with the silica GI MMF which easily coupled with the VCSEL. This low-distortion performance is related to the strong mode coupling in the low-noise GI POF, which stabilizes the VCSEL owing to the self-coupling reduction of the optical feedback into the VCSEL cavity. This suggests that the novel GI POF allows for highly-stabilized multilevel transmission for consumer-friendly 8K interface. In the conference, we will also discuss the mechanism for the stabilization effects of the low-noise GI POF using theoretical analyses.