Introduction
Optical
fibres are arguably one of the world’s most influential scientific developments
from the latter half of the 20th century. Normally we are unaware that we are
using them, although many of us do frequently. The majority of telephone calls
and internet traffic at some stage in their journey will be transmitted along
an optical fibre. More indirectly, many of the systems that we either rely on
or enjoy in everyday life such as banks, television and newspapers as (to name
only a very limited selection) are themselves dependent on communication
systems that are dependent on optical fibres.
There are
various other uses of optical fibres which are irrelevant to this essay,
although it is interesting to note some that many people are unaware of. The
first application of optical fibres was for designer lighting – this has
recently become popular again. Currently, techniques have been, or are being,
developed to detect chemicals along pipelines (by using unprotected chemically
sensitive fibre), detect plutonium smuggling, monitor strain in yacht masts,
allow communication with CAT scan patients, construct gyroscopes with no moving
parts, transmit images from telescopes, and possibly guide atoms (although this
is very early in the stages of development).
In this
essay I shall attempt to cover the many areas of importance in optical fibre
design. Only some crucial areas such as fibre design will be covered in detail;
others such as signal sources and detectors will be discussed more briefly.
I shall
also give some indication of the systems currently in use commercially and some
of the systems currently being developed.