Transmission Loss of Optical Fibers; Achievements in Half a Century

Abstract

This paper reviews the evolutionary process that reduced the transmission loss of silica optical fibers from the report of 20 dB/km by Corning in 1970 to the current record-low loss. At an early stage, the main effort was to remove impurities especially hydroxy groups for fibers with GeO 2-SiO 2 core, resulting in the loss of 0.20 dB/km in 1980. In order to suppress Rayleigh scattering due to composition fluctuation, pure-silicacore fibers were developed, and the loss of 0.154 dB/km was achieved in 1986. As the residual main factor of the loss, Rayleigh scattering due to density fluctuation was actively investigated by utilizing IR and Raman spectroscopy in the 1990s and early 2000s. Now, ultra-low-loss fibers with the loss of 0.150 dB/km are commercially available in trans-oceanic submarine cable systems.

Enhanced-Backscattering and Enhanced-Backreflection Fibers for Distributed Optical Fiber Sensors

“…In glass optical fibers, attenuation is given by extrinsic factors (such as contamination with metal/transition elements, hydroxyls, or particles) and by intrinsic factors (electronic bond absorption, vibrational absorption, and scattering). Telecom fibers have minimized the attenuation due to extrinsic factors and absorption to a level such that more than 80% of the total attenuation around 1550 nm is given by Rayleigh scattering [27]. In the last two decades, ultra-low-loss fibers have resulted from a reduced Rayleigh scattering achieved either by reducing the glass fictive temperature Tf in solid fibers [28] or by propagating most of the mode in air in hollow-core fibers [29].…”

Comprehensive Survey of Research on Emerging Communication Technologies from ICETC2020

“…The development and progress of optical communication technologies are indispensable to support 5G and B5G, and Japan is leading in this research area [225]- [229].…”