Bloomberg Businessweek USA - 02.09.2019

31

By E. Tammy Kim

Photograph by Daniel Shea

Fiber Optics

A successor to the

humble copper-wire

telephone line, fiber

optics carry all manner

of data around the

world in the form of

light. Specialized fiber

optics are also used in

lasers, medical imaging,

and underground

sensors that detect faint

vibrations or monitor

temperature and

pressure.

Transmission fiber

typically comes in a

bundle—a fiber-optic

cable—but each strand

is a feat. Thin as a fishing

line, the fiber has a pure

glass core through which

the light signal travels;

it’s pulled down from

the “V” point of a glass

(silicon dioxide) preform

through glass cladding

that keeps the light

focused inside the core.

At the preform stage—when

the fiber is still a large, dense

cylinder, about 15centimeters

in diameter and many meters

long—it’s treated with vaporized

chemicals that affect the level

of refraction and thus the

movement of light through the

fiber. Germanium, for example,

might be applied to the core to

concentrate the signal; fluorine

on the cladding redirects the

signal to the core. Each type

of fiber, depending on its use,

requires a unique cocktail.

May contain

or require

PRODUCT COURTESY OFS FITEL, FURUKAWA ELECTRIC CO.

1

H

Hydrogen

6

C

Carbon

7

N

Nitrogen

8

O

Oxygen

2

He

Helium

14

Si

Silicon

26

Fe

Iron

9

F

Fluorine

17

Cl

Chlorine

18

Ar

Argon

32

Ge

Germanium