2019-09-02 Bloomberg Businessweek

31

ByE.TammyKim

PhotographbyDanielShea

Fiber Optics

A successortothe

humblecopper-wire

telephoneline,fiber

opticscarryallmanner

ofdataaroundthe

worldin theformof

light.Specializedfiber

opticsarealsousedin

lasers,medicalimaging,

andunderground

sensorsthatdetectfaint

vibrationsormonitor

temperatureand

pressure.

Transmissionfiber

typicallycomesin a

bundle—afiber-optic

cable—buteachstrand

is a feat.Thinasa fishing

line,thefiberhasa pure

glasscorethroughwhich

thelightsignaltravels;

it’spulleddownfrom

the“V”pointofa glass

(silicondioxide)preform

throughglasscladding

thatkeepsthelight

focusedinsidethecore.

Atthepreformstage—when

thefiberis stilla large,dense

cylinder,about 15 centimeters

in diameterandmanymeters

long—it’streatedwithvaporized

chemicalsthataffectthelevel

ofrefractionandthusthe

movementoflightthroughthe

fiber.Germanium,forexample,

mightbeappliedtothecoreto

concentratethesignal;fluorine

onthecladdingredirectsthe

signaltothecore.Eachtype

offiber,dependingonitsuse,

requiresa uniquecocktail.

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