Lecture notes on veer surendra sai university of technology. Optical modulation a tutorial introduction to optical modulation techniques by gary breed editorial director t his article introduces the subject of optical modulation, the process of applying information to a light wave. Fiber optic communication systems and techniques provides solid background in wide ranging topics of fiber optics. A basic fiber optic sensor system consists of an optical fiber and a light modulating arrangement. Measuring bandwidth of 10g laseroptimized multimode fiber. Fiber optics go back as far as roman times, but the first was an optical telegraph, which allowed operators to relay a message from one tower to the next by a series of lights mounted on the towers. Bandwidth is a measure of the datacarrying capacity of an optical fiber. Optical fiber communications by gerd keiser, 4th edition, mc grawhill international editions.
This lecture explains about one of the application of optical properties of material, i. The basic components are light signal transmitter, the optical fiber, and the photo detecting receiver. Optical fiber optical fiber is made from thin strands of either glass or plastic it has little mechanical strength, so it must be enclosed in a protective jacket often, two or more fibers are enclosed in the same cable for increased bandwidth and redundancy in case one of the fibers breaks it is also easier to build a fullduplex system. It is expressed as the product of frequency and distance. The result is that pulses then begin to spread into one another and the symbols become indistinguishable. The first step in the design of an optical communication systems is to decide how the electrical signal should be converted into an bit stream. Fiberoptic communication systems and techniques provides solid background in wide ranging topics of fiberoptics. The design criteria for a fiber optic link design procedure is mainly divided into. The bandwidth and window of fiber optic cable fs community. The communication system of fiber optics is well understood by studying the parts and sections of it. Those light waves may be sent through a transparent medium as a laser beam, or contained within a fiber optic cable. Semiconductor optical amplifiers soas fiber raman and brillouin amplifiers rare earth doped fiber amplifiers erbium edfa 1500 nm.
Fiber types in gigabit optical communications abstract fiber optic cables are the medium of choice in telecommunications infrastructure, enabling the transmission of highspeed voice, video, and data traffic in enterprise and service provider networks. Aug 11, 2017 the noise figure of soa optical amplifier is typically higher, the gain bandwidth can be similar, soas exhibit much stronger nonlinear distortions in the form of selfphase modulation and fourwave mixing. There are two typical choices for the modulation format of the signal. A raman optical amplifier is little more that a highpower pump laser, and a wdm or directional coupler. Besides, optical fiber cable is also light in weight, and all of these features make it an ideal medium for data transmission, which is capable of transmitting unlimited telephone and tv signal. These fibers offer lower splice loss than standard sm fibers and are suitable for a range of applications. Fiber connectors a fiber optic splice establishes an optical connection between two individual optical fibers. All the networks using optical fiber as transmission medium optical networks when transmitted signal remains in optical form till its arrival at destination alloptical network.
There is truly no match for fiber s bandwidth capabilities. Fiber optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The major elements of an optical fiber communication system are shown in the following figure. Sm fiber offers high bandwidth and low modal dispersion. Laser is understood to be the most efficient of em radiation and. All the networks using optical fiber as transmission medium optical networks when transmitted signal remains in optical form till its arrival at destination all optical network. Multimode optical fiber at 850nm is known as the first window, singlemode optical fiber at o band is referred to as the second band. In may 2002, the itut organization divided the fiber optical communication system into six bands as o, e, s, c, l and u6.
Nptel video lectures, iit video lectures online, nptel youtube lectures. In an optical fiber we find two types of dispersions 1 intramodal or chromatic dispersion present in single mode an multimode optical fiber. This is because the bandwidth of optical fibre is almost times. The raman optical amplifiers have a wide gain bandwidth up to 10 nm. Optical fiber characterization nbs special publication 637, optical fiber characterization 1, is a twovolume compilation of previously published nbs technical notes concerning the characterization of optical fibers used for telecommunications. Advanced optical communication nptel online videos. Principles of optical fiber communications tutorialspoint. Introduction to fiber optic sensors 5 temperature, high pressure, corrosive and toxic environments, high radiation, large electromagnetic fields and other harsh environments.
However these systems were limited in bandwidth and optical systems were investigated. The light forms an electromagnetic carrier wave that is modulated to carry information. The fractional bandwidth of this transmission can be calculated as. Satellite communications by timothy pratt, charles bostian and jeremy allnutt, 2 edition, wiley student edition. The fibre optic receiver is the essential component in this process as it performs the actual reception of the optical signal and converts it into electrical pulses.
The technology ofusing multiple optical signals ont he same fiber iscalled wavee gth divisi utipexi g wdm. Mod1 lec11 practical issues in implementation of fiber link. The next piece of the jigsaw fell into place when the first optical fibers with a sufficiently low loss for communications purposes were developed in the 1970s. The key attribute that enables this performance is very low attenuation, i. A typical glass fiber consists of a central core material. Signal processing in optical fibers 303 source transmitter channel receiver user voice data encoding modulation optical fiber wireless demodulation decoding voice data figure 2. Based on rayleigh backscattered light in an optical fiber single mode or multi mode it senses all points along the fiber and monitors acoustic perturbations to the fiber specifications frequency range 1mhz to 100khz spatial resolution 1 m length 50 km strong applications oil. This lowloss wavelength region ranges from 1260 nm to 1625 nm, and is divided into five wavelength bands referred to as the o, e, s, c and lbands, as shown in figure 1 and 2. Attenuation limit the optical power reaching the receiver. Typical block diagram of a digital communications system. A tutorial introduction to optical modulation techniques.
The reason its called single mode is that only one mode of light can pass through at a time. The fiber manufacture technology now helps us in precise desing of optical fibers as per requirements and using such sophisticated technology. The bandwidth of single mode fibers is much higher than in mu lo. An antitank missile uses fiber optic cable for flight control. Recent years have seen an exponential increase in demand for large bandwidth and high data rate applications. Electronics advanced optical communication youtube. Fiber optic cables are lightweight, take up less space, and are also flexible. For fiber optic cable, theoretically speaking, its bandwidth is infinitely high, transmission capacity is infinitely large and the transmission distance is infinitely far. To reduce fiber dispersion, new types of fiber were invented, including dispersionshifted fibers itu g. Jun 30, 2015 optical communication is basically guided transmission of em waves based on the snells law.
Optical communication is basically guided transmission of em waves based on the snells law. It is true that single mode fiber has unlimited bandwidth. Within the fibre optic receiver, the photodetector is the key element. The field of fibre optics communications has exploded over the past two decades. The topics covered include modes of optical fibers, impairments in optical fiber channel, lasers and photodiodes, optical amplifiers, wdm components, and digital fiberoptic communications. The optical fiber mainly consists the following six parts as shown in figure core. The traditional overfilled launch ofl method of measuring bandwidth in multimode fiber has been replaced by new, more advanced techniques.
Optical signals are amplified up to 10 db in the network optical fiber. So a single mode fibre fibre with one bound eigenfield actually has in theory two such channels, one for each polarisation state of the bound eigenfield. Apr 16, 2018 62 videos play all fiber optic communication systems and techniques prof pradeep kumar k iit kanpur july 2018 acacia talks coherent understanding the cfp2 digitial coherent optics module. The core medium refractive is always greater than the cladding refractive index. The technical notes appeared in the late 1970s and early 1980s, which was the period of commercial. An overview of macrobending and microbending of optical. Fiberoptic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. Medical equipment uses fiber optics to illuminate and observe inside the body and in some cases to send highenergy laser pulses through the fiber to perform internal surgery.
Dispersion is the spreading of the optical pulses as they travel down the fiber. Higher numerical aperature na mean higher coupling from source to fiber, and less losses across joints. Multiple choice questions and answers on optical fiber. Fiber optical signal in fiber optical signal out pump power optical amp medium weak signal amplified signal some types of oas that have been demonstrated include.
Satellite communications by timothy pratt, charles bostian and jeremy allnutt, 2. The advent of 850 nm vcsel light sources and 10g laseroptimized 50 m multimode om3 fiber has enabled costeffective 10g transmission for short reach enterprise applications. A variety of semiconductor photodetectors may be used as fibre optic receivers. Latency in optical transmission media is a consequence of limited velocity in the optical media. Optical fiber, its working principle, design, types, properties an. Now, there is optical communication theory and optical communication engineering design. Optical communications became a possibility after the first lasers were developed in the 1960s. Yet, the semiconductor optical amplifier is of small size and electrical pumped, which is often less expensive than edfa. Fiberoptic communication is mainly conducted in the wavelength region where optical fibers have small transmission loss. The first transatlantic telephone cable with optical fibre in 1988. For example, a fiber with a bandwidth of 500mhzkm megahertz kilometer can transmit data at a rate of 500mhz along one kilometer of fiber.
A bandwidth can also indicate the maximum frequency with which a light source can be modulated, or at which modulated light can be detected with a photodetector in the area of optical fiber communications, the term bandwidth is also often inaccurately used for the data rate e. It may be required to fix broken fiber connection or to tap the fiber for additionalconnections ee4367 telecom. Fibre optic receiver fiber receivers electronics notes. Photosensitive sm fiber photosensitive single mode fiber is designed to provide high photosensitivity for uv radiation. As a consequence of its optical characteristics, the chromatic dispersion of a fiber can be changed by acting on the physical properties of the material. Depending on the type of application and the reach to be achieved, various types of. This dispersion is due to finite bandwidth of the signal.
Fiberoptic communication systems and techniques course. The loss profile of an optical fiber with respect to frequency or wavelength is a very smooth. The topics covered include modes of optical fibers, impairments in optical fiber channel, lasers and photodiodes, optical amplifiers, wdm components, and digital fiber optic communications. Optical communication pdf notes oc pdf notes smartzworld. Signal distortion on optical fibers attenuation nptel. Fibre is an integral part of modern day communication infrastucture and can be found along roads, in buildings, hospitals and machinary.
Therefore, we note that uniform amplitude response condition is well satisfied for the optical. Fiber is preferred over electrical cabling when high bandwidth, long distance, or immunity to electromagnetic interference are required. Introduction to fibre optics jodrell bank observatory. The diameter of the cladding is 125 m for both fiber types. An overview of macrobending and microbending of optical fibers. There is truly no match for fibers bandwidth capabilities. This is due to intrinsic properties of the material, glass. Fiberoptic communication is the most modern and advanced mode of data. The mechanism that limits a fibers bandwidth is known as dispersion. Advanced optical communication advanced optical communication. Power received can be related with the transmitted as. The advantages of fiberoptic sensing are well known and have been widely presented 3, 4, 2123.
Optical fibre communication fiber telecommunications. A good order of magnitude rule of thumb for the maximum possible bandwidth of an optical fibre channel is about 1 petabit per second per optical mode. Our complete selection of sm fiber can be viewed here. Feb 15, 2012 the bottom picture shows the size comparison between a copper cable and an optical fiber, both carries the same bandwidth. Optical fibers are recognized as the superior medium for delivering high bandwidth communications signals over long distances. What is the bandwidth and window of fiber optic cable. What are the good sources to learn the basics of optical.
Rp photonics encyclopedia bandwidth, optical spectrum. Revised march 19, 2020 page 2 of 4 aerial fiber optic cables fttx drop cables typical optical cable specifications. Bandwidth limitations bandwidth of an optical fiber determines the data rate. The diameter of the core is 50 m for a multimode optical fiber and nine m for a singlemode optical fiber. Optical fiber networks have high capacity can be used for providing the high bandwidth services even in wireless, infrared means high bandwidth connectivity. The bottom picture shows the size comparison between a copper cable and an optical fiber, both carries the same bandwidth. Wdm optical network divide the vast transmission bandwidth available on a fiber into several different smaller capacity channels nonoverlapping bandwidths, each of these channels can be operated at a moderate bit rate 2. Advanced optical communication nptel online videos, courses. The optical carrier frequency in the range 10 to 1016 hz generally in the near infrared around 1014 hz or 105 ghz yields a far greater potential transmission bandwidth than metallic cable systems i.
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