Single-mode systems and components for longer wavelengths (Invited Paper)

Single-mode optical fiber transmission technology in the m wavelength region is reviewed. Owing to low fiber loss in the spectral region and to wide-band single-mode fiber characteristics, longwavelength single-mode fiber transmission systems are capable of high data-rate transmission over tens of kilometers distance without intermediate repeaters. The advantages of the systems and progress in fibers, fiber splicing, and devices are reviewed in detail. Using low-loss fibers and recently developed semiconductor lasers, transmission performance is confirmed at 1.05, 1.1, and m wavelengths. At m, where fiber dispersion almost vanishes, gigabit-per-second pulse signals are successfully transmitted over 20 km without intersymbol interference. The maximum tested data rate is 1.6 Gbit/s, at which 13-km nonrepeatered transmission is confirmed. At m, where ultimate low-loss characteristics are expected in silica fibers, 100 Mbit/s transmission is successfully demonstrated over a 29-km repeater span. These high data-rate transmission capabilities over long fiber spans are attractive for future communications networks which may provide a variety of services at reduced system cost and with improved maintenance and installation convenience.