Advantages And Disadvantages Of Optical Fibers

Advantages And Disadvantages Of Optical FibersA neat travels in straight lines as we know it is highly impossible to make it follow a cut path to glimmer approximately corners. In 1970s at that place was a great improvement and quicker growing in lineament eyes communications. The main idea of blankly in communication strategy is evolved from simple indicate fires and lamps. Claude chappe has a first directionrn attempt in opthalmic telecommunicate built in the 1790s.The first problem was alleviated with the advent of semiconductor device age, the semiconductor laser invented by Theodore maiman in 1962 light-emitting diode(light emitted diode) is improved in ocular fictitious character which solved the problem o0f passing light through air. The communications through opthalmic lineament was proposed in 1966 by Charles Kao and Charles Hockham of the standard telecommunication laboratory in England. In the past few decades m whatsoever technologies atomic number 18 introduced among them ocular fibre communication is the best communication system.The main comp sensationnts of opthalmic fibre ar philia, lining and coating. The main duty of nitty-gritty is, it carries a light from sender to receiver.CoreIt is a smallest cancel in opthalmic fibre communication system.It is very(prenominal) delicate visual fibre line of workGenerally it is do up of plastic or internal-combustion engine.The core made up with glass is mixed with pure silicon dioxide other impurities manage germanium or phosphorous.These impurities be added to improve the refractile advocate at certain conditionsThe range of glass core is from 3.7 to 200.1.48 is the refractile king of coreThe core made with plastic is larger than glass.CladdingIt is the preventive and surrounded layer of core.It provides the low reflective index.In glass veneer the core and lining is made with same materialDifferent metre of impurities is added to both core and cladding in order to make a difference in refractive index among them is about 1%.1.46 is the refractive index of cladding125 and 140 atomic number 18 the standard cladding diamsCoatingThis is the main protective layer for the entire optical fibre.It protects the optical fibre from shocks and other external damages.Coating has an outside diameter of each 250 or 500.Coating is colour little but to name the coating in more or less applications it is coloured.2) Advantages of Fiber opticsThe band breadth of optical fibre is very high when comp atomic number 18d with other communications.To increase band width in fibre optics is very easy.Data transmission is very fast in fibre optics.We thunder mug transmit data to longer distances without any noise.It is very difficult to tap the information because it is much secured.3) Disadvantages of Fiber optics institution of fibre optics is very cost.When we face any problem with fibre optics we affect special test equipment.Communication with case optic cable is more cost when comp bed with disparate broad band conjunction costs.In cracker-barrel atomic number 18as reference optic communications are very less, in these long time this is one of the main disadvantage of type optic.4) Fibre Optic disadvantageesDue to bending and breaking of optical fibre cables firinges are occurred in fibre optics. Mainly there are two types. internal losings.Extrinsic injuryes.4.1) indwelling lossesA slight variation from one fibre to a nonher fibre even manufactured with in condition tolerances. Losses are occurred by these variations. In immanent losses there are four types of losses. They areNA (Numerical Aperture) match losses.Core diameters pair losses. coaxial match losses.Elliptical mismatch losses.Cladding diameter mismatch loss.1) NA (Numerical Aperture) mismatches lossesIf there are two optical fibres are repaired we are connecting them with splices during this connection mismatches are occurred because the cone of accep tance in the receiving persona ordurenot gather the complete light emitted by the contagion fiber. This means the light is not travelling whole. This mismatch loss is known as numeric aperture mismatch loss.2) Core diameter mismatch lossesThe difference amid the core diameters is the reason of this loss. When the transmitting core greater than the receiving core or transmitting core is lesser than the receiving core light is not on the whole travelling. This type of mismatch is called as Core diameter mismatch losses.3) C at oncentric mismatch lossesIn exemplar conditions the core the core and cladding are concentric, that means a single geometric centre is overlap between them. The fibre core is likely to be offset by a slight marrow from the cladding centre. In fiber cores when the transmitting and receiving are non concentric. They go forth not meet exactly and the light culmination from the transmitting fiber is garbled.4) Elliptical mismatch lossesIf the fiber cores not the utterly circular and fiber cores and cladding are not perfectly concentric this types of losses are occurred. The transmitting optical fiber core is not match with receiver core.5) Cladding diameter mismatch loss.If the diameter of the cladding are not same on the both fiber optics. This type of mismatch is occurred. This means the transmitter light is not completely sending to receiver core.4.2) Extrinsic lossesGenerally in an ideal optical fibre the cores are centred on each other they are placed at 90 degrees angle to their faces. The ends should be in potent contact. Any miss arrangement in these conditions can cause some loses in the signal. There are three types of extrinsic losses.Lateral displacement. rarity breakup.Angular misalignment.1) Lateral displacementIf the centres of core of two optical fibers are do not match this loss whitethorn occur. If the displacement increases less light from the transmitting fiber makes its way into the receiving fibre. A little a mount of displacement is acceptable in larger fibers because the majority of the core s surface area is still in contact. In smaller fibers a slight offset can place the centre of the transmitting core entirely outside of the receiver core.2) End SeparationThe end separation loss is due to Fresnel reflection, it takes place when the light passes from fiber refractive index into the air and vice versa. In refractive index each and both variegate causes an amount of reflected light and therefore the loss is occurred.3) Angular MisalignmentThe optical signal will suffer from these losses when the fibers meet an angle. The solution for this loss is to arrange the fibre end properly that the both ends are in the same line during splicing.4.3) Major causes of losses ingress loss.Scattering loss. additive scattering losses.Non Linear scattering losses.Coupler losses.Insertion losses. reprimand losses. impurity losses.Macro bending and micro bending losses.Packing fraction loss.Absorption loss Absorption loss is occurred by the impurities in the fiber it self such as water and metals. cloth absorption losses Material absorption losses are occurred by absorption of photons within the fiber these losses represent a fundamental lower limit to the attainable loss.Intrinsic absorption losses Interaction with more than one component with glass leads to the intrinsic absorption loss.Scattering lossI couples energy point to radiation modes which causes the energy losses from the fiber. If there is a core diameter irregularity in fiber rag direction excessively a reason of scattering losses.Linear Scattering lossThe quantity of light queen is transferred from jolt is directly pro portional to the occasion in the shake it also causes by inhomogeneties in the glass when the size of it smaller than wave length.Non linear scattering lossIf the electric field with in the fiber has high values then it leads to the presence of non linear scattering ,it also causes when sign ificant power is scattered in all the directions.Coupler lossThe fiber optics coupler are active or passive devices the join loss in optical fiber is defined as,= output power =inputpowerConnection losses increased by fiber to fiber connection due to the following sources of intrinsic and extrinsic. Mainly we have four types marriage losses1.Reflectionlosses.2.Fiber separation.3.Fiber misalignment.4.Fiber mismatchInsertion lossesInsertion losses are combination of distich loss and additional fibre losses. If joints of fiber can increased the attenuation of fibre this is done in multimode operation. Fiber joints can leads to the second order mode in single mode fiber.Reflection lossesLight waves of reflection and transmission occur because frequency do not match the natural resonant frequencies of vibration of object.Impurity lossesThe first source of impurities material in glass fibre is metallic-looking ions, the loss due to this reduces the contribution below 1DB/KM.Macro and microbending lossesThese loss may occur due to sharp bend in fibre, to father high losses a short length of optical fibre is to be bend, as tight as the fibre optic the losses are worst. The major problem in macro losses is in the hands of the installer.The losses in micro bends is same as the macro bands but it just differs in the size and cause. The radius is gibe or less then the diameter the outer layer will shrink and get shorter when the fibre is too cold, fibre optic cables are available with a range of temperatures from C to C.MacrobendMicrobendPacking fractin losses bingle emitter sometimes uses a bundle of fibres, if claddings are in contacts many fibres are packed together. Large area source can match a large bundle in order to eliminate area mismatch loss. Small sources can emit less like than the larger once , in single fibre larger one has more power to couple into a bundle than into a single fibre.Fibre optic as a signal detection elementSensor provide link to e mbrasure between the electronic units and physical world the sensing element can remark physical and chemical qualities such as temperature, rack, vibration, flow , acceleration, proximity,and chemical concentrations. A basic sensor is made upof a light source(laser or led), a length of fibre and optical detector. Fibre optic itself acts as a sensor by varying he intensity of light these measurements are done. Only the source and the detector is required in the sensors hence it is very simpler.Based on the performance characteristics there are four different types of sensors they are1. Extrinsic sensors.2. Intrinsic sensors.3. Fibre bragg grating (FBG sensors).4. farseeing arrest grating sensor.Extrinsic sensorIn extrinsic sensors the outside part of the fibre undergoes to the sensing effect. The fibre acts as a collection system in light delivery. For example a chemical sensor utilizes a sensitive material on the tip, light is pass through the fibre and reflected back. In the chemical solution as the concentration alterations the tip properties may change and the reflection of the light also changes which gives the measure of chemical concentration.Intrinsic sensorIn intrinsic sensor the changes takes place within the fibre. The change is outside the fibre and the fibre remains unchanged when the intrinsic sensor is in contract to extrinsic sensors. For example when a fibre with scoop surfaces is placed between two plates, the fibre is pressed by the plates when the pressure increases the attenuation of the fibre increases due to this.Bend and micro bend sensorBent in a optical fibre leads to a portion of propagating light beam along the bend is incident at angles essential be smaller than the critical angle by which attenuation, this can be used for sensing measure load and stream are free-base by this mechanism, lose of power occurs if any load lead to a bending of fibre. This measure gives the distribution of strain and load with the use of lost p ower. A series of random bends and small bends along the fibre is known a micro bending. It acts as a coupling between cladding and core modes in a single mode fibre and between multimode fibre.Fibre bragg grating(FBG Sensor)TO MEASURE TEMPERATURE AND STRAINTo measure sensing mechanical strain, temperature and acceleration we use FBG sensors. Parameters that changes any of these results in a change in reflected wavelength, these changes when measured, sensing or external perturbations can be done.Long period grating sensorPeriodic perturbations along the length of the fibre with periods greater than hundred micro meters which includes coupling between the light propagating in core and cladding is long period grating. Cladding code cast the power transmitter through the fibre used to find the refractive index when there is any change in the medium around the fibre.Interferometric sensors In this the light is transmitted through to fibres. one of them (reference arm) isolated from e nvironment and its properties are constant. And another fibre (measure arm) is exposed to parameter during sensing. The face of the light is changed by the parameters. The interferometric sensors has the greatest sensitivity and it has highest performance capabilities.The Interferometric sensor. ( John F.R, 1997, pp-543).ADVANTAGES OF FIBRE OPTICS SENSORSIt allows an access to normally inaccessible areas of interest.It is an non-electrical.Due to small size and less burden of the sensors it effective in cost.It has high sensitivity.It has high reliability.It is very easy to install. transmitterTransmitter converts electrical signal into light signal. It has two functionsLight emittergovernorLight emitterIt works as a soirce of light coupled into optical cable.RegulatorIt modulates the light to represent the binary data.Light emitting diodeThe transmitter are directly modulate when the drive menstruation passed through the LED is varied. The power is directly proportional to the cu rrent flowing in the LED. match to the applications the drive currents is measured. The drive current is switched on and off in digital applications. And the current is varied in Analog application. The LED transmitter is packed with the receiver since the space is reduced and simplifies the circuit designing which reduces the cost.Characteristics of the LEDRecommended operate conditions.Electrical characteristicsOptical characteristicsData rateRecommended operating conditionsIt describe the temperature and potential drop ranges that device can operate in without damage.Without any fluctuations the maximum and minimum operating temperatures can be measured.Electrical characteristicsIt describes..the required supply currentData output voltagesSignal detect output voltagesRise drib timesOptical characteristicsIt includesMinimum optical input powerMaxcimum optical input powerOperating wavelength