OREANDA-NEWS. Nippon Telegraph and Telephone Corporation (NTT, Chiyoda-ku, Tokyo, CEO: Hiroo Unoura), and two partners, Fujikura Ltd. (Fujikura, Koto-ku, Tokyo, President and CEO Masahiko Ito), and Hokkaido University (Sapporo, Hokkaido, President Keizo Yamaguchi) have demonstrated the world’s highest density optical fiber using a deployable optical fiber diameter of less than 250 µm. This optical fiber contains 19 optical paths (cores) that can support six kinds of optical signals (modes), and it provides 114 (= 6 modes ? 19 cores) spatially multiplexed communication paths (channels) in one optical fiber.

A glass diameter of less than 250 µm makes it possible to ensure that optical fiber has sufficient reliability (i.e. bendable fiber that does not break). Accommodating 114 channels in one optical fiber enables us to transfer thousands of HDTV videos per second. The achievement indicates the reality of ultra-large capacity optical fiber that can handle a Peta- to Exa-bit transmission capacity.

This remarkable achievement was reported in March as a postdeadline paper at the Optical Fiber Communication Conference and Exposition (OFC 2016), the largest conference on optical communication in North America, which was held in Anaheim, California, USA.

This work was partially based on work commissioned by the National Institute of Information and Communications Technology (NICT).From conventional optical fiber to this achievement

Recent figures released by the Ministry of Internal Affairs and Communications indicate that the data transmission capacity in Japan exceeded 2.5 Tera-bits per second (Tera = 1012) in November 2013. This trend will require a data capacity of 100 Tera-bits per second by the late 2020s. It is also expected that the capacity crunch facing existing optical fiber, which has one optical path (core) supporting one kind of optical signal (mode), may be reached at the same time. This background means we must install additional optical fibers in the 2020s. However, the maximum number of optical fibers that can be stored in one optical fiber cable is limited. We will also need to construct additional optical wiring infrastructure underground and in buildings, if there is insufficient space in the existing infrastructure.

To address these concerns, worldwide research has been under way on new optical fiber that uses space multiplexing technology. For example, multi-core optical fiber accommodates many cores in one optical fiber, and multi-mode optical fiber supports many modes in one core. However, it is difficult to obtain more than 50 communication paths (channels) using one core or mode multiplexing because of the limit to the glass diameter or the controllability of the refractive index profile*4. With this as the background, NTT, Fujikura and Hokkaido University (Laboratory of Information Communication Photonics) combined their expertise to realize an optical fiber with more than 100 channels while maintaining a deployable glass diameter by considering the best mix of core- and mode-multiplexing.