Types of cable

1. Simplex cable
one fiber, tight-buffered (coated with a 900 um
buffer over the primary buffer coating) with Kevlar
(aramid fiber) strength members and jacketed for
indoor use

2. Zipcord cable (duplex cable)
is simply two of simplex cables joined with a thin
web or conjoined jackets.

3. Distribution cable

4. Breakout cable

It is made of several simplex cables bundled together.
This is a strong, rugged design, but is larger and more
expensive than the distribution cables

5. Loose tube cables: These cables are
composed of several fibers together inside a
small plastic tube, which are in turn wound
around a central strength member and jacketed,
providing a small, high fiber count cable.

6. Ribbon Cable: This cable offers the highest
packing density, since all the fibers are laid out in
rows, typically of 12 fibers, and laid on top of each
other

Modes and Classifications

􀂙Mode
􀁽 the propagation characteristics of an
electromagnetic wave as it travels through a type
of fiber
The number of propagation modes of a fiber is
related to the core diameter, index of refraction and
wavelength of light
􀂙Two basic modes of transmission
􀁽 Single Mode
􀁽 Multimode

Single Mode Step-Index Fiber

Small core diameter
􀂙index of refraction for core is smaller than
multimode
􀂙only one mode of propagation
􀁽 all light rays travel the same path
􀂙light source is Injection Laser Diode(ILD)
􀂙Long distance, high speed transmission

Snell’s Law

􀂙Fundamental principle of
light
􀁽 when it strikes the interface
between two transparent
mediums, a portion of the
light is reflected back into
the first medium and a
portion is transmitted into
the second
􀂙Snell’s Law - predicts the
path of light rays as they
travel between media


Index of Refraction [IOR]
􀁽 Determines the amount of bending that light
undergoes when entering a different medium
􀁽 if the media is more dense waves will bend
towards the normal
􀁽 if the media is less dense waves will bend
away from the normal


Light enters a medium whose index of
refraction is less than the medium from
which it exits will refract away from the
normal
􀁽 unless
􀂃 the angle of incidence exceeds the critical angle

Electromagnetic spectrum

􀂙Covers DC to cosmic rays
􀂙Three basic categories of light
􀁽 Infrared: wavelength from 770 to 106 nm
fiber optics 800 - 1600 nm
􀁽 Visible: 390 to 770 nm
ranges from violet 390nm to red 770 nm
􀁽 Ultraviolet: 10 - 390 nm

Advantages of Optical Fibers

Electrical Isolation
􀂙Immunity to Interference
􀂙Increased Bandwidth
􀂙Lower Loss
􀂙Decreased Size & Weight
􀂙Remote Access
􀂙Safe

Disadvantages of Fiber

Interfacing costs
􀂃 Electronic facilities to optics interface to fiber
􀂃 test and repair equipment is expensive
􀂃 splicing is costly and tedious
􀂙Strength
􀂃 by itself the tensile strength is about 1 lb
􀁽 coax (RG59U) 180 lb
􀂙Remote Powering of Devices
􀂃 cannot carry electrical power through the fiber
􀂃 can be manufactured with companion copper wire

Applications

Communications
􀁽Long Distance Telecoms
􀁽LANs
􀁽 Industrial Control
􀁽 Avionics
􀁽 Military
􀂙Sensing
􀂙Power Delivery
􀂙Illumination

Aircraft, ship and automobile data buses
􀂙CCTV for security
􀂙Links for consumer digital stereo
􀂙Today fiber optics is either the dominant
medium or a logical choice for every
communication system

Theory of light

􀂙 Two theories of behavior
􀁽 Particle
􀁽 “light consisting of rapidly moving particles”
􀁽 Supported by Sir Isaac Newton
􀁽 Wave
􀂃 Thomas Young – light as a series of
waves
􀁽 Double slit experiment discounted particle
theory
􀂙 Quantum Theory
􀁽 Max Planck’s (1858-1947) The founder of the
quantum theory
􀁽 Showed that light emitted or absorbed behaves
as a wave but also as an electromagnetic
particle called a photon
􀂃 Photon – possessing energy in proportion to its
frequency

Fiber Optics

A communication technology using
transmission of light through ultra-pure fibers
of glass, plastic, or other transparent media.
􀂙Rays of light propagate through a transparent
media by reflecting off its boundaries
􀁽 Total Internal Reflection

Fiber Optic - Historical Dates

1854: John Tyndall demonstrated
that light could be guided through
a stream of water based on the
principle of total internal reflection

1958: Invention of LASER
􀂙 1966: Experiments in England show that glass could be made
more transparent by reducing impurities -- minimizing light loss
􀂙 1967:Losses in optical fiber reported at 1000dB/km
􀂙 1987: losses at 0.16dB/km
􀂙 1988: ANSI introduce the Synchronous Optical Network (SONET)
􀁽 fiber WAN backbone
􀂙 1998: Dense wavelength-division multiplexing (DWDM)
􀁽 80-color-band systems operating at 400 Gpbs