what is fiber optic technology?

Answer 1

Optical Fibres are fibres of usually glass, sometimes plastic in audio applications, usually about 120 micrometres in diameter, which are used to carry signals in the form of pulses of light over distances up to 50 km without the need for repeaters. These signals may be coded voice communications or computer data.

Reflection and Refraction of Light
When light travelling in a transparent material meets the surface of another transparent material two things happen

some of the light is reflected

some of the light is transmitted into the second transparent material

The light which is transmitted usually changes direction when it enters the second material. This bending of light is called refraction and it depends upon the fact that light travels at one speed in one material and at a different speed in a different material. As a result each material has its own Refractive Index which we use to help us calculate the amount of bending which takes place. Refractive index is defined as:-

n=C/V

where

n is the refractive index

C is the speed of light in a vacuum

V is the speed of light in the material

Two possible cases exist.

These are:-

where light goes from a material with a low refractive index to one with a high refractive index, OR

where light goes from a material with a high refractive index to one with a low refractive index.

The transmitted ray now tries to travel in both materials simultaneously For various reasons this is physically impossible so there is no transmitted ray and all the light energy is reflected. This is true for any value of q 1, the angle of incidence, equal to or greater than q c This phenomenon is called Total Internal Reflection (TIR).

We can define the two conditions neccessary for TIR to occur

The refractive index of the first medium is greater than the refractive index of the second one.

The angle of incidence, q1, is greater than or equal to the critical angle, qc

The phenomenon of TIR causes 100% reflection. In no other situation in nature, where light is reflected, does 100% reflection occur. So TIR is unique and very useful.

Light Sources
There are two main light sources used in the field of fibre optics.-

Light Emitting diodes (LED's)

Laser Diodes (LD's)

LED's
An LED is a p-n junction diode in a transparent capsule usually with a lens to let the light escape and to focus it. LED's can be manufactured to operate at 850 nm, 1300 nm, or 1500 nm. These wavelengths are all in the infrared region. LED's have a typical response time of 8 ns, a linewidth of 40 nm, and an output power of tens of microwatts.

Laser Diodes
A laser diode Is an LED with two important differences

(1) The operating current is much higher in order to produce OPTICAL GAIN

(2) Two of the ends of the LD are cleaved parallel to each other. These ends act as perfectly aligned mirrors which reflect the light back and forth through the "gain medium" in order to get as much amplification as possible

The typical response time of a laser diode Is 0.5 ns. The linewidth is around 2 nm with a typical laser power of 10's of milliwatts. The wavelength of a laser diode can be 850 nm, 1300 nm, or 1500 nm.

Answer 2

A technology that uses glass (or plastic) threads (fibers) to transmit data. A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves.
Fiber optics has several advantages over traditional metal communications lines:

Fiber optic cables have a much greater bandwidth than metal cables. This means that they can carry more data.
Fiber optic cables are less susceptible than metal cables to interference.
Fiber optic cables are much thinner and lighter than metal wires.
Data can be transmitted digitally (the natural form for computer data) rather than analogically.
The main disadvantage of fiber optics is that the cables are expensive to install. In addition, they are more fragile than wire and are difficult to splice.

Fiber optics is a particularly popular technology for local-area networks. In addition, telephone companies are steadily replacing traditional telephone lines with fiber optic cables. In the future, almost all communications will employ fiber optics

Answer 3

Fibroptics is the technology of transmitting information via light waves through very thin glass tubes. It makes use of the physics principle of Total Internal Reflection, in that if a beam of light in a material (the glass) hits a less dense material at a certain angle, it will be reflected back instead of passing through the glass and out of the tube.

Thus, by bouncing the light beam in the glass, information signals can be transmitted at high speed and over very long distances with very little attenuation or signal loss, especially as compared to electrical signals.