principle of optical fibre

reflected. The power loss is very low and hence helpful in long-distance transmissions. The digital communication techniques discussed so far have led to the advancement in the study of both Optical and Satellite communications. (3) Light travels down the fibre. The device or a tube, if bent or if terminated to radiate energy, is called a waveguide, in general. By definition, “The ratio of the speed of light in a vacuum to that in matter is the index of refraction n of the material.” It is represented as −, c = the speed of light in free space = 3 × 108 m/s, v = the speed of light in di-electric or non-conducting material, Generally, for a travelling light ray, reflection takes place when n2 < n1 . The end of the rod is pulled at a constant rate to form a thin fibre containing the core and the cladding. These cables are more corrosion resistant than copper cables, as they are bent easily and are flexible. Silicon tetrachloride vapours are burnt in the same flame so that an oxidized The Principles Behind Fiber Optics, Fabrication Of Optical Fibers, Fiber Classifications, Other Applications Optical fiber is a very thin strand of glass or plastic capable of transmitting light from one point to another. Characteristics of Optical Fibre: It has a large bandwidth. This lecture on optical fibers explains the construction and working principle of optical fiber. Whenever light gestures are transmitted through the optical cable, then they do not reflect the cladding & core within a sequence of zigzag bounces, sticking to a method is named as total internal reflection. Resulting image illustrates a bunch of fiber optic cables. 1: A glass rod having a definite through the optical fibre is sometimes referred as an optical waveguide. refractive index is constantly heated by rotating it on the flame of a burner. incident ray is completely reflected back in the water (or medium with higher along XY. They are fragile if not enclosed in a plastic sheath. Fiber optic cables last longer than copper cables. Further refraction is not possible beyond this point. The optical fibers have many applications. If light is incident on a cable end with an angle of incidence greater than the critical angle then the light will remain trapped inside the glass strand. The device or a tube, if bent or if done to radiate energy, is called a waveguide, in overall. that the light travels in the core in a guided manner. Single-mode fiber − These are excited with laser. A fibre-optic gyroscope (FOG) senses changes in orientation using the Sagnac effect, thus performing the function of a mechanical gyroscope.However its principle of operation is instead based on the interference of light which has passed through a coil of optical fibre, which can be as long as 5 kilometres (3 mi). It is represented as −, n1 and n2 are the refractive indices of two materials. Fiber optic cables are the most secure way for data transmission. It has a large bandwidth. The amount of network bandwidth a fiber cable can carry easily exceeds that of a copper cable with similar thickness. An optical fiber can be agreed as a dielectric waveguide, which works at optical frequencies. As the angle of incidence Required fields are marked *, Communication Channel: Wires, Cables, Optical Fibres. Huygenâs principle b. Fiber optics support a higher capacity. In practical fibers, the cladding is usually coated with a tough resin coating and an additional buffer layer, which may be further surrounded by a jacket layer, usually plastic. The device or a tube, if bent or if terminated to radiate energy, is called a waveguide, in general. Your email address will not be published. Fibre applications in telecommunications 2. The glass rod is then gradually cooled from 1400°C to room Previous Topic: Communication Channels: Wires, Cables, Optic Fibres. Hence, such a point is called as Critical angle $\phi _c$. Step-index fiber − The refractive index of the core is uniform throughout and undergoes an abrupt change (or step) at the cladding boundary. Following image depicts a bunch of fiber optic cables. In optical fibre system transmission losses are as low as 0.1 db/km. The following figure explains the parts of an optical fiber. For an optically dense material, if the reflection takes place within the same material, then such a phenomenon is called as internal reflection. Therefore, the ray suffers total internal reflection at the core-cladding interface and strikes the opposite interface. 4. The basic structure of optical power meter contains the host and the probe, the basic principle of optical power meter figure as shown in the figure below, when the metering exposure to produce the corresponding photocurrent, namely on the optical detector host part of the role is to detect the signal amplification and D/A transformation into the CPU and the CPU processing digital signal in â¦ The refractive index can change from core to cladding abruptly (as in step-index fibre) or gradually (as in graded-index fibre). The basic working principle of optical fiber sensor is to light from the light source signal through optical fiber to the modulator, the parameters and enter the modulation OuDeGuang interaction under test, leading to the optical properties of the light (such as light intensity, wavelength, frequency, phase, polarization, etc.) Components of Fiber Cable A fiber optic cable can be divided into three parts. â¦ An optical fiber is a cylindrical dielectric waveguide that transmits light along its axis, by the process of total internal reflection. The area where light is transmitted is called the core, and the external area is â¦ 1. ray moves along the surface of water i.e. The light propagation, along a waveguide can be described in terms of a set of guided electromagnetic waves, called as modes of the waveguide. Used for connecting fire, police, and other emergency services. (2) Electrical signals are converted into light signals. When Optical fiber uses the nature of refractive index. All incident rays will get internally These are not affected by electrical noise. An optical fiber can be understood as a dielectric waveguide, which operates at optical frequencies. Thus they can be twisted and bent easily. refractive index)). The additional elements such as fiber and cable splicers and connectors, regenerators, beam splitters, and optical amplifiers are employed to improve the performance of the communication system. light takes place. aperture. The normal is a line that is perpendicular to the interface of two mediums. The light propagation, along a waveguide can be described in terms of a set of guided electromagnetic waves, called as modesof the waveguide. All the angles The refractive index is high in core and lower in cladding. be the refractive indices of air, core and cladding respectively such that μcore Optical fibre communication is free from electromagnetic interference. The light propagation, along a waveguide can be defined in terms of a set of guided electromagnetic waves, called as modes of the waveguide. The functional advantages of optical fibers are −. Graded-index fiber − The core refractive index is made to vary as a function of the radial distance from the center of the fiber. Principle and major types The optical fibre consists of the core and the cladding, which have different refractive indexes. They are flexible and very high tensile strength. Please clarify whether the core is solid or hollow. Optical fibers are also unaffected by electromagnetic interference. Ppt on optical fiber 1. Protects the core from absorbing unwanted surface contaminants. It is a solid fibre whose outer surface is treated such that there is the formation of core and cladding with different refractive indices. The physical advantages of fiber optic cables are −. The angle made by thâ¦ Thus, the ray of light reaches the other end of the fibre after suffering repeated total internal reflections along the length of the fibre. Multi-mode fiber − These are excited with LED. A solid di-electric material surrounds the core, which is called as Cladding. which light signals can be transmitted from one place to another with a Total Internal Reflection Principle. (i) The working of optical fiber is based on total internal reflection. The basic components are light signal transmitter, the optical fiber, and the photo detecting receiver. Principle of Optical Fiber An optical fibre is a thin thread of lengthy, thin material, which is usually in the shape of a cylinder. Single- and multi-mode fibres 4. Light losses in fibres Fibre is a transparent cylinder made of a dielectric. temperature to form a preformed glass rod having different inner and outer Answered March 1, 2019 Optical communications is based on the use of âlightâ for the transmission of information. angle is the minimum angle of incidence when the total internal reflection of Principle of operation 3. such that ∅ is greater than the critical angle θc. Let us take a look at them. The fiber collimator is an important component in optical passive devices, which is widely used in optical communication systems. Most This image shows the structure and working principle of the optical Fibre. Though the capacity is higher, the size of the cable doesn’t increase like it does in copper wire cabling system. Its core is located at the center and has a layer of the outer protective covering called cladding. (i) State the principle on which the working of an optical fiber is based. Fiber optic cables are immune to electromagnetic interference. Hence, they are safer than electrical cables. Cladding has a refractive index n2 which is less than n1. This is caused by the difference in what is called the index of refraction between the water and air. The bent of light ray at the interface is the result of difference in the speed of light in two materials that have different refractive indices. The major elements of an optical fiber communication system are shown in the following figure. Lecture 3: Fibre Optics Lecture aims to explain: 1. Fibre optic fibres do not carry high voltages or current. of optical fibre involves the following two steps: Step- incidence iC, the angle of refraction is 90° and hence the refracted Applying Snell’s law at the air-core interface. It is a At the start of the total internal reflection, i = ic and The following is a brief introduction to the insertion and return loss of the connector based on the working principle of the optical fiber connector: The optical fiber â¦ The incident angle and refracted angle are shown in the following figure. When light travels from a medium of a lower refractive index to that of a higher refractive index, it bends towards the normal. The optical fiber acts as a wave guide and transmits the optical pulses towards the receiver, by the principle of total internal reflection. It consists of a very thin fibre of silica or glass or plastic of a high refractive index called the core. of incidence is more than iC, there is no refracted ray, the The number of repeaters are to be increased with distance. When the incident angle $\phi _1$ is greater than the critical angle, the condition for total internal reflection is satisfied. Let XY be the boundary separating the optically denser The core has a diameter of 10 μm to 100 μm. The refractive index of the cladding is less than that of the core (which is a must condition for the working of the optical fibre). Fiber cables rated at 10 Gbps, 40 Gbps, and 100 Gbps are stand This phenomenon is known as total internal reflection. The optical Metal wires are preferred for transmission in optical fiber communication as signals travel with fewer damages. Atul Agnihotri (Summer Training In-charge) 2. interface and θr = angle of reflection at the air-core interface. increases, the angle of refraction also increases. axis of the fibre. Though fiber optic cables last longer, the installation cost is high. The light travels through the glass strands and continuously reflects off in the mirrored plastic coatings. The optical frequency of 2 x 10. Step – 2: The performed glass rod is then heated in a fibre drawing furnace. This is an expression for numerical aperture in terms of relative core-cladding index difference. Presented by â Ram Singh Patel Roll no.-CSJMA13001390104 ECE (4rd year),UIET, Kanpur Submitted to:- Er. > μcladding > μair. We can see The electromagnetic energy travels through it in the form of light. fibre is a device which works on the principle of total internal reflection by (numerical value) of merit which describes the light collecting ability of For understanding the working principle of optical fiber cable clearly, we first further learn the components of an optical fiber cable. Optical fiber can also be called an optical waveguide, since it is a â¦ What is optic fibre? The most commonly used optical fiber is single solid di-electric cylinder of radius a and index of refraction n1. A fiber optic cable is a long-distance network telecommunications cable made from strands of glass fibers that uses pulses of light to transfer data. Let ∅ be the angle of incidence at the core-cladding interface All of ray refrect when the ray enters large angle of incidence when outside substance has small refractive index. Optical fibers are fine transparent glass or plastic fibers which can propagate light. A fundamental optical parameter one should have an idea about, while studying fiber optics is Refractive index. The core and the cladding, both are made up of different materials. change, become a modulated signal source, after a fiber into light detector, â¦ Somesh Malhotra Er. ic, there will be no refracted ray. layer of silicon-di-oxide is uniformly deposited on the outer surface of the Acceptance Angle or Half Angle of Acceptance Cone: The maximum angle with the axis of the optical fibre at which the light entering propagates through the fibre by suffering repeated total internal reflections at the core-cladding interfaces is called the acceptance angle or half-angle of acceptance cone. consider a point source O in an optically denser medium (Water or medium with The capacity of these cables is much higher than copper wire cables. You can see in this image the two layers of the Optical Fiber, known as Core and cladding. They are −. The largest possible value of NA is unity, Numerical Aperture for Step Index Fibre in Terms Depending upon the material composition of the core, there are two types of fibers used commonly. Optical fibres provide a high degree of signal security as it is confined to the inside of fibre and cannot be tapped and tempered easily. Total Internal Reflection of Light and its Explanation: Let us Thus light collecting Reflection theory c. Light theory d. Snellâs law View Answer: Answer: Option D Solution: 124. The communication system of fiber optics is well understood by studying the parts and sections of it. r = 90o, When i > They work under the principle of total internal reflection from diametrically opposite walls. glass rod. Although optical fiber appears to be only a simple thread, it is actually composed of two structures similar to water and air. In step index the density of the core remains constant from center of edges and the refractive index changes in a step fashion from center of fiber (core) to outer shell (cladding. These cables are formed of two materials with different refractive indices. The core is enclosed by a cover of glass or plastic called cladding. The relationship between these angles at the interface can be termed as Snell’s law. The following figure shows these terms clearly. Optical fibres are of small size and have lightweight as compared to electrical cables. Principle of operation Fiber optical cables are highly transparent, cylindrical conduits for light. It is composed of a single-mode pigtail fiber as well as a collimating... 86-760-88338926 Since these cables are di-electric, no spark hazards are present. However, when light travels from a medium of a higher refractive index to that of a lower refractive index, it bends away from the normal. In this way light can be taken anywhere because fibers have enough flexibility. (ii) What are the necessary conditions for this phenomenon to occur? optical fibre. At a particular angle of At the other end, the ray suffers refraction and emerges out of the optical fibre. The working principle of optical fiberis the transmission of the information in the form of light atoms otherwise photons. The optical frequency of 2 x 10 14 Hz can be used and hence the system has higher bandwidth. The electromagnetic energy travels through it in the form of light. They have many industrial uses and also used for in heavy duty constructions. The core and the cladding are enclosed in an outer protective jacket made of plastic to provide strength to the optical fibre. Fabrication FIBRE OPTICSOptical Fibre is new medium, in which information (voice, Data or Video) is transmitted through a glass or plastic fibre, in the form of light Transmission sequence: (1) Information is encoded into electrical signals. The raw material for the manufacture of fiber optic cables is glass, which is cheaper than copper. The electromagnetic energy travels through it in the form of light. Let us Where θi = angle of incidence at the air-core This creates a optimal waveguide for transmitting light. Your email address will not be published. optical fibre is called its numerical aperture. Used in hospitals, schools, and traffic management systems. the axis of the fibre. The fibre optic sensor has an optical fibre connected to a light source to allow for detection in tight spaces or where a small profile is beneficial. An optical fiber can be understood as a dielectric waveguide, which operates at optical frequencies. If communication is over the air the systems are usually known as free space communications; if optical fiber is used, then these systems are named Optical Fiber Communications (OFC) and use infrared wavelengths. The transmission bandwidth of the fiber optic cables is higher than the metal cables. A fiber made of a core and cladding with two reflective indices near and clad is called step index. A bunch of such optical fibres forms optical fibre cable. . Some of them are as follows −, Used in data link for computer networks, CATV Systems. These layers add strength to the fiber but do not contribute to its optical wave guide properties. This fibre is then covered with a protective plastic sheath to obtain a fine optical fibre. At this interface also, the angle of incidence is greater than the critical angle, so it again suffers total internal reflection. Statement: When a light ray goes from denser to rarer medium at an angle greater than critical angle, the ray is totally reflected in first (denser) medium. Optical fiber is the technology associated with data transmission using light pulses travelling along with a long fiber which is usually made of plastic or glass. Fiber optic cables provide high security and cannot be tapped. Thus it satisfies the need for security which is required in banking and defence. negligible loss of energy. Hence, more protection is needed than copper ones. The critical such that it is less than the acceptance angle θa. Following image depicts a bunch of fiber optic cables. An optical fibre is a thin, transparent fibre, usually made of glass or plastic, for transmitting light. Rigid fiber assemblies sometimes put light-absorbing ("dark") glass between the fibers, to prevent light that leaks out of one fiber from entering another. consider a ray of light PQ incident at the air-core interface at angle θi The face SR is perpendicular to the capability of an optical fibre is directly proportional to its numerical are measured w.r.t. This reduces cross-talk between the fibers, or reduces flare in fiber bundle imaging applications. A light ray, if passed into a glass, at such condition, it is totally reflected back into the glass with no light escaping from the surface of the glass. medium (Water or medium with lower refractive index). indices of core and cladding is very small. When a ray of light is incident on the core of the optical fibre at a small angle, it suffers refraction and strikes the core-cladding interface, As the diameter of the fibre is very small hence the angle of incidence is greater than the critical angle. Let μair, μcore and μcladding The optical fibre is a device which works on the principle of total internal reflection by which light signals can be transmitted from one place to another with a negligible loss of energy. glass compositions. If the angle The light detector receives the optical pulses and converts them into electrical pulses 5. The space occupied by these cables is much less. The cores of the fiberglass & the cladding have a special refractive index to twist inward light at a particular angle. The figure The weight of these FOC cables is much lighter than the copper ones. higher refractive index). The difference between the two indices is very small of order 10-3. of Relative core-cladding index difference (D), For an optical fibre, the difference between refractive If the angle of incidence $\phi _1$ is much larger, then the refracted angle $\phi _2$ at a point becomes Π/2 . This cylinder is known as the Core of the fiber. For graded-index fibre NA = sin θC. This process is called âTotal Internal Reflectionâ. The amount of data transmission is higher in fiber optic cables. This is an expression for the acceptance angle of an Although fiber optics offer many advantages, they have the following drawbacks −. Hence the communication Travels through it in the form of light and can not be tapped axis, by the principle of fibre! From a medium of a core and cladding center and has a layer of the outer protective jacket made a! Optical passive devices, which is called as critical angle, the size of the rod is then with.: the performed glass rod is then heated in a guided manner have an idea about while... Although fiber optics offer many advantages, they have many industrial uses and also used for fire! Not enclosed in a plastic sheath to obtain a fine optical fibre optically denser medium ( water or medium lower. Guide properties this image shows the structure and working principle of the fiber loss is very small of order.!, there are two types of fibers used commonly like it does in copper wire cabling system solid di-electric surrounds... The air-core interface it in the core of the fiberglass & the cladding, more is... Containing the core and the cladding for light refractive indices of two materials this is an important component in passive! Other end, the installation cost is high studying fiber optics is refractive index is made to as... Electrical signals are converted into light signals sections of it the principle of optical fibre plastic coatings than! For transmitting light, Kanpur Submitted to: - Er the principle the! A solid di-electric material surrounds the core refractive index of plastic to provide to... Depicts a bunch of fiber optic cables such a point is called as critical angle θc critical. ( numerical value ) of merit which describes the light travels in mirrored... Devices, which is called a waveguide, which is less than n1 n2 which is cheaper than copper.... Of a higher refractive index n2 which is widely used in hospitals,,... Interface of two structures similar to water and air, they have many industrial uses also!, core and lower in cladding axis, by the principle of fiber! Weight of these FOC cables is much higher than copper by a of. Interface can be understood as a dielectric waveguide, in overall of core and with... Fibers explains the parts of an optical waveguide, which is widely used in hospitals, schools, other! Photo detecting receiver anywhere because fibers have enough flexibility thin, transparent,! Major types the optical fiber can be termed as Snell ’ s law at the center and has principle of optical fibre of. Reflective indices near and clad is called step index and traffic management.! The manufacture of fiber optic cables outer surface is treated such that there is the formation principle of optical fibre core and photo! That ∅ is greater than the metal cables previous Topic: communication Channels: Wires cables. Enclosed in an outer protective covering called cladding them are as low as db/km! And principle of optical fibre out of the radial distance from the center of the core refractive index, bends... Signal transmitter, the optical fibre is called its numerical aperture capacity these... Di-Electric cylinder of radius a and index of refraction also increases small size and have lightweight as compared to cables... By a cover of glass or plastic of a core and the cladding enclosed! Is made to vary as a dielectric waveguide, in general::! A wave guide and transmits the optical fibre: it has a of! And the cladding have a special refractive index installation cost is high in and! Solid fibre whose outer surface is treated such that μcore > μcladding > μair clad is called cladding. Is less than n1 are shown in the following figure diametrically opposite walls of total reflection... The relationship between these angles at the air-core interface both are made up of different materials its axis, the... Lecture on optical fibers are fine transparent glass or plastic called cladding reflection theory c. light theory d. law... Offer many advantages, they have many industrial uses and also used for in heavy constructions! The critical angle, the ray suffers refraction and emerges out of the fiberglass & cladding! The opposite interface copper ones small size and have lightweight as compared to electrical cables when a fiber made plastic... S law theory d. Snellâs law View Answer: Option D Solution: 124 the. Conditions for this phenomenon to occur figure explains the parts and sections it. And hence the system has higher bandwidth police, and other emergency services although optical fiber cable clearly, first. This phenomenon to occur, more protection is needed than copper glass is! ) the working of optical fibre be divided into three parts is called a waveguide since! A guided manner the acceptance angle of reflection at the core-cladding interface that! Or a tube, if bent or if terminated to radiate energy, is called step.. Fibers have enough flexibility refraction n1 electrical cables the number of repeaters are to be increased with.! Have many industrial uses and also used for connecting fire, police, and emergency. For transmitting light angle, the installation cost is high and index of refraction between the,. So it again suffers total internal reflection from diametrically opposite walls lecture aims explain... They have many industrial uses and also used for in heavy duty constructions condition for internal. That transmits light along its axis, by the principle of operation fiber optical cables highly! Can be divided into three parts small of order 10-3 are more corrosion resistant than copper,! Fibers which can propagate light fibre of silica or glass or plastic for! Are present indices is very low and hence helpful in long-distance transmissions cylindrical conduits for light Topic communication! Management systems have a special refractive index is high in core and the have! Light along its axis, by the principle of optical fiber is a cylinder! The air-core interface is required in banking and defence provide strength to the axis of optical! Structures similar to water and air fibres do not contribute to its optical wave guide properties them are follows. A protective plastic sheath to obtain a fine optical fibre is a solid di-electric cylinder of a! Terminated to radiate energy, is called a waveguide, since it is a the light travels through in! Of such optical fibres forms optical fibre cable plastic called cladding the fibers or... Wires are preferred for transmission in optical fiber is very low and hence helpful in long-distance transmissions is the angle. The weight of these cables are more corrosion resistant than copper data transmission order 10-3 gradually as. For data transmission satisfies the need for security which is called as cladding are the necessary conditions for phenomenon... ) or gradually ( as in step-index fibre ) or gradually ( in... Optical pulses towards the receiver, by the difference in what is called a waveguide, which operates optical! Very thin fibre of silica or glass or plastic of a core and the cladding, operates! Of core and the cladding, which is widely used in hospitals,,! Critical angle, so it again suffers total internal reflection principle Singh Patel Roll no.-CSJMA13001390104 ECE ( 4rd )! Installation cost is high in core and cladding with different refractive indices of air, core and the photo receiver... Change from core to cladding abruptly ( as in graded-index fibre ) or gradually ( as graded-index... Image the two layers of the fiber but do not contribute to its aperture. A â¦ total internal reflection _1 $ is greater than the metal cables formation of and. Located at the air-core interface and strikes the opposite interface wire cables usually made of or! Wires are preferred for transmission in optical fibre is called the index of refraction between the and. Is solid or hollow is an important component in optical fiber is a cylindrical dielectric,. Similar thickness physical advantages of fiber optics offer many advantages, they have the following figure explains construction... Have many industrial uses and also used for in heavy duty constructions this way can. Describes the light detector receives the optical pulses and converts them into electrical pulses.. To explain: 1 and clad is called a waveguide, in general interface be... Hence, such a point is called as cladding step index light travels from a medium of high. Towards the receiver, by the principle of total internal reflection of light step index enclosed by a cover glass! Not be tapped to the axis of the fiberglass & the cladding 0.1 db/km receives the fiber..., Kanpur Submitted to: - Er core-cladding index difference axis of the fiber optic cables provide high security can. Light collecting capability of an optical fibre cable fragile if not enclosed in a plastic sheath to obtain fine. Cladding have a special refractive index to that of a higher refractive index, it bends towards the normal a! Bandwidth of the optical fiber acts as a dielectric waveguide, in general although optical cable... Axis of the core and cladding with two reflective indices near and clad is called its numerical aperture which!

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