Optical amplifiers such as raman optical amplifiers and erbiumdoped fiber amplifiers are used in fiberoptic networks to amplify optical signals. Raman amplifiers can be distributed, lumped or discrete, or hybrid. In this way, a raman amplifier can be combinedfa booster or inlineed with a n. Optical amplifiers require electrical or optical energy to excite pump up the state of. Optical amplifiers are important in optical communication and laser physics. It makes raman easier to understand,lists down its. The fiber gain media of the former is generally within 10 km. It can also be a bulk crystal, a waveguide in a photonic integrated circuit, or a cell with a. Common types of raman amplifiers principle theory of raman gain noise sources related information introduction this document describes the practical aspects of raman amplifier implementation in the optical network. Xin jiang, in optical performance monitoring, 2010. Distributed raman sources and patented super raman pumps. It consists of little more than a highpower pump laser, usually called a raman laser, and a wdm or directional coupler. Fiber raman amplifier fra fiber raman amplifier fra is also a relatively mature optical amplifier. White paper applications for distributed raman amplification.
In a typical fiberoptic communications link, erbiumdoped fiber amplifiers may be located at network nodes between successive spans of transmission fiber. In a fra, the optical signal is amplified due to stimulated raman scattering srs. More specifically, the optical amplifier adjusts the gain that it applies to the optical signals so that it. Raman amplification in fiber optical communication systems. A raman amplifier is an optical amplifier based on raman gain, which. Raman amplifier ra amplifies signal by stimulated raman scattering srs. The raman optical amplifiers have a wide gain bandwidth up to. Optical amplifiers are optical active components as a circuit enabling technology for optical communication networks. Raman amplifiers used in conjunction with edfas semiconductor optical amplifiers small package potential use for lowcost applications potential use for optical switching opti 500 c, spring 2011, lecture 23, introduction to optical amplifiers 1 types of optical amplifiers. Optilab provides ra as a pre amplifier to compensate the propagation loss in the long fiber. Oba17 optical booster amplifier avara technologies. Increasing the power level at the end of the transmission line according to receiver sensitivity. The raman optical amplifier cards are part of the cisco ons 15454 mstp intelligent dwdm architecture engineered to reduce dwdm.
An optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal. Raman amplifiers ra utilize the nonlinear optical effect in the fibers to amplify week signal. The main advantage of raman amplifier is that its gain spe. In general, fra can is divided into lumped type called lra and distributed type called dra. Raman amplifiers cannot compete effectively with edfas. Distributed raman amplification dra has emerged in recent years as a key technology for modern optical networks, and especially for coherent transmission. Advantages of raman amplifiers first, raman gain exists in every fiber, which provides a costeffective means of upgrading from the terminal ends.
Optical amplifiers are optical active components as a circuit enabling technology. Osa analytical study on the stimulated raman scattering. Integrated optical amplifiers on silicon waveguides. The distributed type utilizes a transmission optical fiber as an active medium 6. Optical amplifiers are key components in realizing high levels of photonic integration as they compensate for optical losses from individual photonic elements. Introduction to optical amplifiers 417 a raman amplifier is distributed over a long span of optical fiber. For longhaul optical transmission systems broadband hybrid amplifiers with multipump raman amplification and edfa have been a demanding technique. In a raman amplifier, the signal is amplified due to stimulated raman. As a result of this, another signal photon is produced, with the surplus energy resonantly passed to the vibrational states of the medium. Optical amplifiers like erbium doped fiber amplifier edfa and fiber raman amplifier fra are considered as one of the most important elements in technology for optical communication networks. Recognizing this, finisar has invested significant resources in developing and producing stateoftheart raman amplifiers and hybrid raman.
Monitoring raman amplified optical links while in service introduction erbiumdoped fiber amplifier edfa and raman amplifiers are the two main solutions for optical signal amplification in long distance, optical communication systems. Pp ap here are some typical numbers for the raman amp. A raman optical amplifier is little more that a highpower pump laser, and a wdm or directional coupler. The optical amplification occurs in the transmission fiber itself. Specifically, by exploiting raman amplification with an incoherent pump, the amplified signal is shown to develop a series of temporal intensity spikes whose peak power follows a powerlaw probability distribution. In a distributed raman amplifier, the optical fiber link itself is used as the amplification medium.
Oba17 optical booster amplifier avara raman and edfa based optical amplifiers provide an efficient, costeffective and reliable way to deliver longhaul pdh, sdh and giga bit ethernet transmission solutions the avara optical pre amplifier product is rack mountable raman amplifier with integrated edfa preamp and dcm modules for use in long haul. Recognizing this, finisar has invested significant resources in developing and producing stateoftheart raman amplifiers and hybrid raman edfas with. For 10 nm raman fiber amplifiers, the raman fiber features very low loss, as its a good alternative to the 1480 nm laser diode sources that are limited to 100 to 200 mw output power compared to the 1 watt raman laser alternative. Ppt edfa raman amplifier raman amplification optical. The raman amplifier is different from the edfa in that it is a distributed amplification system. Raman gain properties of optical fibers with a high content of. Semiconductor optical amplifiers soas fiber raman and brillouin amplifiers rare earth doped fiber amplifiers erbium edfa 1500 nm, praseodymium pdfa 0 nm the most practical optical amplifiers to date include the soa and edfa types. Erbium doped fiber amplifier edfa, 15001600 nm band, also. Telluritebased fiber raman amplifiers, semiconductor optical amplifiers and fiber optic parametric amplifiers, principle of. In this video, i have covered raman amplifier with following outlines. Raman amplifier gain equations gr is called the raman gain coefficient units of mw. Indeed, laser diodes are limited to 200mw of optical output power while raman lasers can generate 1w. For example, a pump wave at 1064 nm leads to the largest raman gain at a.
An optically pumped raman amplifier has been demonstrated 1, but an electrically pumped silicon optical amplifier is. The raman active medium is often an optical fiber, although it can also be a bulk crystal, a waveguide in a photonic integrated circuit, or a cell with a gas or liquid medium. Comparison of the optical amplifiers edfa and soa based on. Boosting of an optical signal without any conversion of the light into an electrical signal. Performance analysis of a hybrid raman optical parametric. Raman amplification is an alternative amplification technology and has been increasingly implemented in longhaul system. The rst occurred in 1999, and now raman ampli cation is an accepted technique for enhancing system performance. Its features are put to use in this reference design for laser and thermoelectric cooler control in edfa and raman optical amplifiers. Optical ampsraman and erbiumdoped fiber amplifiers pp.
Monitoring raman amplified optical links while in service. Fibre raman amplifiers are being deployed in many new longhaul and ultra longhaul fibreoptic transmission systems, making them the first and most widely commercialized nonlinear optical devices in telecommunications. Such optical fibers allow the pump power and the length of the employed fiber segment to be minimized. Optical amplifiers provided by fibermart are designed for all network segments access, metro, regional and long haul and applications telecom, cable and enterprise. Firstly, it has a wide band, while the band of edfa is only from 1525 nm to 1565 nm and 1570 nm to 1610 nm. Pdf a 90nm wideband 15001590nm optical amplifier consisting of a dispersioncompensatedfiberbased raman fiber amplifier and a semiconductor. To transmit a signals over long distances 100km, to compensate attenuation losses. Amplifier booster, to increase the output power at the beginning of the link pre amplifier preamp, high input sensitivity. The optical amplification occurs in the transmission fiber itself, distributed along the transmission path. Rare earth doped fiber amplifiers erbium edfa 1500 nm, praseodymium.
In this paper, the stimulated raman scattering srs threshold of the distributedpumped fiber amplifier consisting of multiple sub amplifiers is analytically studied based on the rateequation model. Optical signals are amplified up to 10 db in the network optical fiber. An optical amplifier may be thought of as a laser without an optical cavity, or one in which feedback from the cavity is suppressed. Optical amplifiers for nextgeneration telecommunication. The raman amplifier is another widely used fiber amplifier in longhaul systems. A high power pump laser is injected at the far end and travels backward in the fiber to amplify. Raman amplifiers can serve as lownoise preamplifiers, or they can meet the full amplifier needs in all raman systems. Boosting of an optical signal without any conversion of. An optical amplifier pump laser reference design based on the amc7820 rick downs data acquisition products abstract the amc7820 is an integrated circuit designed for analog monitoring and control. A free powerpoint ppt presentation displayed as a flash slide show on id. Currently it is not possible to create a fully optical communication system without a software tool which simulates an optical communication line in real conditions prior to its construction. We report experimental observation and characterization of rogue wavelike extreme value statistics arising from pumpsignal noise transfer in a fiber raman amplifier. A raman amplifier is an optical amplifier based on raman gain, which results from the effect of stimulated raman scattering.
We have a series of erbiumdoped fiber amplifier edfa optical amplifiers, including dwdm edfa for dwdm systems, catv edfa for catv applications, sdh edfa for sdh networks. The aim of this article is to establish a comparison between the edfa erbium doped fibre amplifier and soa semiconductor optical amplifier optical amplifiers in the wdm wavelength division. Typically, the optical pump is introduced at the end of a length of fiber in order to provide optical gain that increases towards the end of the fiber. They are available in modules for easy integration or turnkey solution platforms, e. Optical amplifiers are a key enabling technology for optical communication networks. Raman amplification an overview sciencedirect topics. Figure 2 optical gain spectrum of a hybrid optical amplifier click to enlarge a raman optical amplifier is not a black box like an edfa. With the help of the formula, the effect of the pumping scheme on the srs suppression of the. After knowing the basic information of edfa and raman optical amplifiers, you must consider that the raman amplifier performs better for two main reasons. An optical amplifier pump laser reference design based on. Together with telecommunication system and technology allowing the transmission of channels over the fiber, optical amplifiers have made it possible to transmit many data over distances from 100 km and up to transoceanic distances, providing the data capacity required for. Raman amplification is a distributed process where signal amplification takes place inside the transmission fiber. Osa optical roguewavelike extreme value fluctuations. If the amplifier is contained in a box at the transmitter or receiver end of the system, it will be called a discrete raman amplifier.
Raman gain in fiber depends mainly on the opcal frequencies. Semiconductor optical amplifiers soa, 400 2000 nm band. The srs threshold formula is presented where the predictions agree well with the numerical results. An optical amplifier is adapted to cancel the raman gain of an optical transmission path that degrades those optical signals occupying the low end of the bandwidth such that the power is transferred from the latter signals to the optical signals occupying the high end of the bandwidth. A fiber optical amplifier combining optical parametric and raman processes was. Pdf semiconductor optical and raman hybrid amplifier. While edfas are still the most deployed amplifiers, raman based solutions are gaining momentum in the metro. The cisco ons 15454 multiservice transport platform mstp offers a raman optical amplifier card figure 1 operating in the cband region of the. Different pump configurations fordiscrete raman amplifier.
There are two main reasons of using raman amplifier first is the. White paper introduction to optical amplifiers finisar corporation. Us6088152a optical amplifier arranged to offset raman. Raman amplifier archives tutorials of fiber optic products. Raman cband optical amplifier for the cisco ons 15454.
Demonstrations that used raman ampli cation are circled. Optical amplifiers venkat venkataramanan instute for opcal. New pumping methods and materials are also improving the performance of raman amplifiers. Noise figure analysis of distributed fibre raman amplifier g.
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