“FIBRE OPTICS AND LASERS”

SUMMARY
Fiber optics, or optical fiber, refers to the medium and the technology associated
with the transmission of information as light pulses along a glass or plastic strand
or fiber. Fiber optics is used long-distance and high-performance data networking.

Optical fibres are glass or plastics as thin as human hair, designed to guide light
waves along their lengh. An optical fibre Works on the principle of total internal
reflection. Optical fibres are constructed either as a single fibre or a flexible bundle
or a cable. A fibre bundle is a number of fibres in a single jacket.

OBJECTIVES
 Identify the different types of effects that lasers and fiber optics have in their
fields of application.
 Determine the good performance and materials with which they can be man
ufacture; quality, study and research.
 Research of their different fields, such as in medicine for the use of wound
healing, for pain, inflammation, in sports medicine and even for aesthetic
use.
 Different types of contraindications and precautions to consider.

JUSTIFICATION
The knowledge of this document will allow us a broad concept about the
characteristics of optical and laser fibers. It is intended to facilitate and improve
learning on this topic.
 INTRODUCTION
The field of fibre optics communications has exploded over the past two decades.
Fibre is an intergal part of modern-day communication infrastucture can be found
along roads, in buildings, hospitals and machinery. The fibre itself is a strand of
silica based glass, its dimensions are similar to those of a human hair, surrounded
by a transparent cladding. Light can be transmitted along the fibre over great
distance at very high data rates providing an ideal medium for the transport of
information. This section will provide explanations for some of the terms associated
with the field of fibre optic engineering for telecommunications.
 “FIBRE OPTICS AND LASERS”
LASER
A laser is a device capable of emitting a very powerful beam of light. He the term laser, itself,
comes from the acronym LASER (Light Amplification by Stimulated Emission of Radiation). It is a
device used to concentrate the light in a narrow beam, through which that concentrated and thin
beam of consistent way, very effectively.

The light emitted from this device radiates differently than normally it radiates from atoms, which
do so randomly and without coherence. That is, the atoms radiate a great jumble of photons that
disperse in every way, without one determined, while the laser, so to speak, concentrates and directs
them. In other words, the laser is nothing more than highly organized light, also called coherent. All
emitted waves have the same wavelength and orientation. All photons have the same energy and the
same drive.

Coherent or laser light has three fundamental characteristics:

a) Monochromatic, all light rays, have the same color.

Radiation representation of a filament lamp and a laser emitter where appreciate the
monochromaticity, coherence and directionality of the beam
 The operation of a laser
A laser device uses an effect of quantum mechanics to generate that beam of light with size, shape
and controlled direction. Light rays in their normal state, such as when they come from the Sun,
they travel radially with respect to their source and decrease with distance. A laser, on the other
hand, is a light source that travels in parallel and its energy practically does not decrease with
distance.

As a result, a light wave that bounces off the mirrors originates at the same time that escapes
through the translucent mirror. The laser is formed by a nucleus that is usually of elongated shape, it
can be a crystalline structure (made for example of ruby) or a tube ofglass containing gas. Next to
the core is the exciter, responsible for causing the light excitation of electrons inside the nucleus and
the third a component of a laser are parallel mirrors, which are placed at both ends of the core One
of them is semi-reflective which allows the partial passage of light, by where the light beam of a
laser comes out.

Emission sources
Laser source

 Active material: ruby with chromium atoms, helium-neon gas, carbon dioxide, argon,
gallium arsenide.
 Two mirrors inside (semi-reflective).

Laser classes (according to the emission source)

 Solid type radiation: Rb, Cr and Nd.

Types of laser

Semiconductor

Substance that, without being insulating, has a conductivity much lower than metal.

The diode is achieved by adding impurities to crystals of GaAs in the melting state. Minerals with
different electrical characteristics (let the current pass in one direction only).

Recombinations of electrons and holes that produce detachments of the light energy

He-ne

 A cylindrical tube with gas (He 90% -Ne 10%).

Optical fiber is a transmission medium commonly used in data networks; a very fine thread of
transparent material, glass or plastic materials, for which they are sent pulses of light that represent
the data to be transmitted. The beam of light is completely confined and propagates inside the fiber
with a reflection angle above the total angle of reflection, depending on Snell's law. The light source
can be laser or an LED.

By seeing in detail how the optical fiber is composed, we will understand its advantages and
disadvantages, as well, we will have a global vision of this medium. This example is about a cable
composed of many parts, it is necessary to understand that there are many types of cables that adapt
to different occasions (interior, exterior, etc.) but I took this as a reference because you can see in
detail what elements a cable can contain. This will help because commonly in fiber optic cable
catalogs, they specify that they are compounds, therefore, knowing the components and so that they
work, we can choose the best cable for what we are riding.

The two physical principles by which fiber works are Reflection and Refraction. They are to blame
for carrying this forward.

Refraction: it is the change of direction that the waves carry when they pass from a medium to
other. Simply and for better understanding, this is experienced when we put a spoon in a glass of
water and it seems to move inside this

Reflection: it is also the change of direction of the wave, but towards the origin. This would be
what what happens when we look in the mirror without reflection, we could not comb our hair or
shave in front of the mirror.
Fibers are widely used in telecommunications, since they allow to send large amount of data over a
great distance, with speeds similar to those of radio and higher to conventional cable. They are the
means of transmission par excellence by being immune to electromagnetic interference, also used
for local networks, where you need to take advantage of fiber optic over other transmission media.

Fiber optic communications

Fiber optic is used as a transmission medium for telecommunications networks, because of their
flexibility the optical conductors can be grouped together forming cables. The fibers used in this
field are plastic or glass, and sometimes of both types. For interurban uses they are made of glass,
due to the low attenuation they have.

Multimode and singlemode fibers are used for communications, using multimode for short
distances (up to 500 m) and single mode for long distance couplings. Because single mode fibers
are more sensitive to splices, welds and connectors, fibers and their components are more expensive
than those of fibersmultimode.

Types according to the Propagation mode

The different paths that a beam of light can follow inside a fiber are they call propagation modes.
And according to the propagation mode we will have two types of fiber optic: multimode and single
mode.
Multimode fiber

A multimode fiber is one in which light beams can circulate for more than one way or way. It
supouse that no everybody arrive at the same time. A multimode fiber can have more than a
thousand modes of light propagation. Multimode fibers are commonly used in short distance
applications, less than 2 km, is simple to design and economical. The core of a multimode fiber has
a higher refractive index, but of the same order of magnitude, than the coating. Due to the large core
size of a multimode fiber, It is easier to connect and has a greater tolerance to less precise
components.

Single mode fiber

A single mode fiber is an optical fiber in which only one light mode is propagated. Is achieved
reducing the diameter of the fiber core to a size (8.3 to 10 microns) that only it allows a propagation
mode. Its transmission is parallel to the fiber axis. Unlike of multimode fibers, single mode fibers
allow to reach large distances (up to 400 km maximum, using a high intensity laser) and transmit
high rates of information (tens of Gbit / s).