Handbook of Optical Fibers and Cables, Second Edition

Murata

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781351829960
• Edition: 2
• Topic: Tecnología e ingeniería
• Subtopic: Ingeniería eléctrica y telecomunicaciones

This work covers the history of optical communications, fibres and fiber cables, and compares optical fibres with other transmission media. It also discusses optical fibre materials, reliability and manufacture, illustrates the design, construction and properties of recent cables used for optical fibre, describes fibre splicing and presents automated fibre splicing machines, and more.

1

Introduction

This chapter relates the history of optical communications, including the history of optical fibers.

1 HISTORY OF OPTICAL COMMUNICATIONS

1.1 Early Optical Communications

The flare has been a means of communication from the days of ancient Egypt to relatively modern times. Romans are said to have built flaring towers, changed the color of the flaring smoke, and sent information of more than two bits with smoking and smokeless flares. Later, people used telescopes in addition to such flares, and in the seventeenth century, the distance of effective communication covered by flare signaling reached a few kilometers.

1.2 Optical Communications at a Standstill [1]

In 1791, the semaphore signaling system was invented by Chappe of France. It was used in all regions of Europe and spread even to North Africa. Its golden age came around 1844, when it was capable of a total coverage of 5000 km.

In 1845 Morse invented telegraphy, and as this invention was put to practical use, the semaphore signal was gradually phased out of service. The invention of wireless telegraphy by Marconi of Italy in 1896 directed radio engineering to the development of high frequencies, that is, short wavelengths. Progress in this somewhat slowed, however, after the development of millimeter wave communications in 1940.

After the invention of laser in 1960, which led to the development of the 1 = 0.5 μm wavelength band, and the announcement of a low-loss optical fiber in 1970, the center of development in telecommunications jumped from the 1 mm wavelength to the 1/1000 mm wavelength.

2 HISTORY OF OPTICAL FIBERS

Table 1 gives a chronology of the research and development of optical fibers. Because of its coherent characteristics, the laser, when first developed, was expected to be a light source for future information transmission. More than a decade passed, however, without its practical application in telecommunications. During that period, the solid-state laser was developed into the semiconductor laser, which permits easy modulation. The semiconductor laser, however, has a short life at room temperature and thus had very little chance of practical application.

In 1966, Kao and Hockham [2] published their report of a new concept for a transmission medium. This was the first report of optical communications, in which they pointed out the possibility of information transmission by optical fibers.

In 1970, the Corning Glass Works in the United States announced its development of fiber with a loss of 20 dB/km [3, 4]. According to the experience of the communications engineers, when the loss of a transmission medium is not more than 20 dB/km and when the transmission device has a lifetime of more than 1500 hr, its potential for transmission is worth study.

The Corning announcement gave impetus to the study of the semiconductor laser, which in turn accelerated research on optical fibers. An outstanding invention or development usually has an impact on technological progress. In the case of optical fiber communications, two important developments, the semiconductor laser and the optical fiber, proceeded in parallel, with each alternately playing a leading role. (Such a course of development is very rare, and those concerned with optical communications were lucky to see it.)

It is no exaggeration to say that after the 10 dB/km fiber was announced by the Corning Glass Works in 1970, research has focused on how to reduce transmission loss. Figure 1 shows the yearly reductions made in loss of optical fibers. Loss has been reduced by two digits in 10 years: 20 dB/km (0.85 μm) in 1970, 0.5 dB/km (1.2 μm) in 1976 [5], 0.157 dB/km (1.55 μm) in 1984 [6], and 0.154 dB/km (1.55 μm) in 1986 [7], when it approached its theoretical minimum. It can be said that these figures represent the smallest losses of transmission media so far obtained.

Table 1 Chronology or Research and Development of Optical Transmission

Year	Light source	Transmission medium
1879		Theoretical study of waveguide (Rayleigh)
1910		Theoretical study of dielectric waveguide (Hondros and Debye)
1920		Experimental study of dielectric waveguide (Schriever)
1951		Development of glass fiber for medical use
1960	Invention of ruby laser (Maiman, Javan)
1961	He-Ne laser oscillation (Bell Laboratories)	Mode theory of dielectric waveguide (Snitzer)
1962	GaAs semiconductor laser (General Electric, IBM, MIT)	Study of lens array waveguide (Goubou et al.)
1964		Experiments of the above (Bell Labs) Study of gas lens (Bell Labs) Suggestion of graded index fiber (Nishizawa and Sasaki, Tohoku University)
1965	CO2 laser oscillation (Bell Labs)	Study of thin-film optical waveguides (Karbowiak)
1966		Dielectric fiber surface waveguides for optical frequencies (Kao and Hockham)
1969		Trially made graded index fiber-Selfoc (Uchida and Kitano) Graded index rod (Bell Labs)
1970	GaAlAs laser continuous oscillation (Bell Labs, USSR, NEC)	Development of low-loss silica fiber (20 dB/km) (Corning Glass Works) Concept of weakly guiding fiber (Gloge)
1972	GaAlAsSb laser oscillation (NTT)	Development of 4 dB/km fiber (Corning Glass Works)
1973		Development of the MCVD proce...