Fundamentals of Plastic Optical Fibers

Appendix

Progress in Low-Loss and High-Bandwidth Plastic Optical Fibers^*

A.1 Introduction

One¹ of the Nobel Prizes in physics in 2009 was awarded to Charles Kao for “groundbreaking achievements concerning light transmission in fibers for optical communication.” In the 1960s, glass optical fibers (GOFs) that could be used for transmitting light had already been developed [2, 3]. However, these fibers exhibited significant propagation losses above 1000 dB/km; thus the transmission distance was severely limited. Kao made a discovery that led to a breakthrough in fiber optics. After closely examining the possibilities for reducing propagation losses, he realized that the attenuation of existing fibers were orders of magnitude above the fundamental limit [4]. He theorized that by using a fiber of the purest glass, it would be possible to transmit light signals over 100 km, in contrast to fibers available in the 1960s that could only realize a distance of 20 m. His prediction of the future potential of low-loss optical fibers inspired other researchers to make great efforts toward its realization. Just 4 years later, in 1970, the first ultrapure fiber with an attenuation of 20 dB/km was successfully fabricated [5]. Others soon followed, and losses were pushed down to the theoretical limit (0.2 dB/km) [6–8]. A first-generation fiber-optic communication system was successfully deployed in 1976, and since then GOFs have steadily connected the world. Today, over a billion kilometers ...