Recently, ultra-high definition (UHD) displays have been rapidly developed for video formats with 4K (3840x2160) and 8K (7680x4320) resolutions. In Japan, 4K/8K broadcastings are scheduled to be started, accelerating research and development of 4K/8K distribution technologies. Current UHD displays require uncompressed video transmission with a bit rate well above 100 Gb/s, suggesting that extremely high bit-rates are required even at home in the upcoming 4K/8K era. Therefore, consumer-friendly pluggable optical interface has been highly demanded.
A graded-index plastic optical fiber (GI POF) has been has been a promising optical interface cable for the consumer applications because of its flexibility, safety, and high bandwidth, which allows for transmission speeds up to ~ 40 Gb/s through a 100-m GI POF. Recently, we demonstrated that GI POFs have noise reduction effects which are closely related to microscopic heterogeneities of the core material. Here, we propose a low-noise GI POF for uncompressed 8K video transmission based on noise-sensitive multilevel pulse amplitude modulation (PAM).
We evaluated worst-case bit-error-rate curve of for the low-noise GI POF and a silica GI MMF in the extremely-short optical link, where we used PAM-2 with the corresponding modulation voltage to minimum symbol-level difference in PAM-4. The results showed that the transmission quality is dominantly determined by not loss and bandwidth but noise and stability. Using the low-noise GI POF, we could significantly stabilized data transmission without precise alignment, angled fiber-facets, and optical isolators. The novel GI POF allows for consumer-friendly optical interface for the 8K video multilevel transmission. This research is based on results obtained from a project commissioned by the NEDO.