Optical amplifiers are important in optical communication and laser physics. Raman amplifier soasemiconductor optical amplifier. Optical ampsraman and erbiumdoped fiber amplifiers pp. 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. Amplifier types doped fiber amplifiers use excitation of ions in the host fiber the erbiumdoped fiber amplifier edfa is most common optically pumped by laser light at higher energy shorter wavelength raman and brillouin amplifiers use nonlinear processes to transfer energy from the pump wave to. Raman amplifier gain equations gr is called the raman gain coefficient. Typically the raman noise figure is 2 to 0 db, which is about 6 db better than the edfa noise figure. The main advantage that this amplifier has over the edfa is that it generates very less noise and hence does not degrade span optical to signal noise ratio. A typical setup of a simple erbiumdoped fiber amplifier edfa is shown in figure 1. Pdf a hybrid configuration of raman amplifier and erbiumdoped fiber amplifier edfa is proposed to obtain a better performance in term of. Erbium doped fiber amplifier commercially available since the early 1990s. An optical amplifier may be thought of as a laser without an optical cavity, or one in which feedback from the cavity is suppressed.
Request pdf design and analysis of a hybrid optical amplifier using edfa and raman amplifier in optical communication network, signals travel through fibers over long distances without. Optisystem optical communication system and amplifier design software. Compared to a edfa, the main advantages of raman ampli cation are an improved noise gure and improved gain atness. Finisars hybrid ramanedfa module enables costeffective deployment of ultralong haul networks as well as the extension of existing longhaul, regional and metro networks, without the need for 3r oeo regeneration. Optical ampsraman and erbium doped fiber amplifiers edfas pp. Raman amplifier, increasing the power level, at the end of the link by use of raman scattering. The wdmtransmitter consists of cw laser, data modulators and a multiplexer. Amplification is achieved with improved osnr behavior and reduction of nonlinear impairments.
One key point to be aware of is that the design of an edfa controller cannot be used as such for a raman amplifier controller. Both gain and gain shape can be adjusted by pump powers. The main data flow model that addresses the simulation of the transmission layer is the component iteration data flow cidf. This chapter describes the technologies needed for cascading an erbiumdoped fiber amplifier edfa and a fiber raman amplifier fra or ra to create a hybrid amplifier ha, the edfaraman ha. Raman amplifier has been demonstrated with two stages of amplification and a noise figure less than 5. Rare earth doped fiber amplifiers erbium edfa 1500 nm, praseodymium.
Optical amplifiers venkat venkataramanan instute for opcal. The main difference between these two techniques is related to the gain medium where the amplification of signal takes place. Also at 120 km edfa, raman and soa have almost the same qfactor. What is the difference between edfa and raman amplifiers. But optical filters and wavelength dependent splitters introduce losses and flexibility issues. The main advantage that this amplifier has over the edfa is that it generates verylessnoise. Before the comparison of the different types of optical amplifiers, lets take a closer look at fiber optic amplifier. Alan kost associate research professor of optical sciences, university of. Distributed raman amplifier dra is one in which the iplexing a pump wavelength with signal wavelength and generally length of fiber is longer100 km. However, additional issues arise in raman ampli cation that are not present in edfa.
Gain flattening of lband edfa raman hybrid amplifier. Noise figure analysis of distributed fibre raman amplifier g. A raman amplifier is an optical amplifier based on raman gain, which results from the effect of stimulated raman scattering. Unlike erbiumdoped fiber amplifiers edfas, where the gain spectrum is constant and determined by the. Raman amplifiers have relatively poor pumping efficiency at lower signal powers. Gain flattening of edfa using hybrid edfaraman amplifier. In the hybrid amplifier case, a flat spectral gain could be achieved due low spectral. Edfas, with the raman pump module serving as a preamplifier to the edfa. Optimizing a raman amplifier is more complicated than for an edfa. An ultrahigh gain and efficient amplifier based on raman.
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. We propose and demonstrate a hybrid claddingpumped multicore erbiumdoped fiber amplifier edfa and distributed raman amplification for space division multiplexing transmission systems. Raman amplifier adjustments require use of an optical spectrum analyzer osa. This is still two orders of magnitude less than predicted theoretically for an efficient raman amplifier 33. Unlike erbiumdoped fiber amplifiers edfas, which boost wavelengths in the 15301610 nm range, a raman amplifier can increase the signal strength of any wavelength by pumping at thz more than. An optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal. Comparison of the optical amplifiers edfa and soa based on. Raman amplifier archives tutorials of fiber optic products. This chapter describes the technologies needed for cascading an erbiumdoped fiber amplifier edfa and a fiber raman amplifier fra or ra to create a. Noise figure of raman amplifier can also degraded by the pump depletion. Edfas use a pump laser 980 nm or 1480 nm to bring up electrons to a higher energy level. The edfa is forward biased with 980 nm while the ra is reverse biased with 1450 nm in the dualpump configuration. Abstract in this paper, the hybrid optical amplifier composed of single erbium doped fiber amplifier and a raman amplifier is proposed for wavelength division multiplexed system and also investigates the impact of reduced channel.
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. It is based on threelevel amplification mechanism in the c band and raman shift amplification mechanism the in l band, respectively. 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. The cidf domain uses runtime scheduling, supporting conditions, datadependent iteration, and true recursion. Analysis of gain and nf using raman and hybrid rfaedfa jmest. Ability to place a loss element dcu, oadm, gain flattening amplifier between the. Hybrid distributed ramanedfa amplifier with hybrid.
Design and analysis of a hybrid optical amplifier using. The aim of this paper is to analyze the performance of. An optical amplifier is a device that amplifies an optical signal directly, without the need to first the most common example is the erbium doped fiber amplifier edfa, where the core of a silica the amplification window of an optical amplifier is the range of optical wavelengths for which the amplifier yields a usable gain. The system is composed of transmitter, fiber, amplifier and receiver. Raman amplifier only and different hybrid optical amplifiers ramanedfa, edfaraman. Length of raman amplifier in edfa we fixed the length of the fiber and found the values of the gain whose results have been shown above. The ramanactive 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. The edfa and raman amplifiers are based on two different physical phenomenons. Today, we are going to study and compare different types of optical amplifiers in this paper. Performance characteristics of dualpumped hybrid edfa. Raman technology is complex a proper design based on raman amplification from the ground up results in equipment as simple, if not simpler, to operate than an edfabased product. In discrete raman amplifiers pump depletion creates gain saturation which affects the amplifier transients, noise figure and pump mediated crosstalk.
However, it demonstrates the potential of the medium. Both the gain and noise figure are experimentally studied and compared with. This paper suggests a hybrid amplifier using an erbiumdoped fiber amplifier edfa and raman amplifier ra with dualpump configuration. Show schematic of wdm optical system with ytterbium amplifier, edfa, raman amplifier using various advance modulation formats. Semiconductor optical amplifiers soas fiber raman and brillouin amplifiers rare earth doped fiber amplifiers erbium edfa 1500 nm. Introduction to optical amplifiers 417 a raman amplifier is distributed over a long span of optical fiber. Pdf the difference between edfa and raman amplifier. Lband edfa with distributed raman amplifier hybrid optical amplifier 6 can provide wide gain. With an edfa and raman the minimum optical power level occurs toward the middle, not the end, of the fiber. The authors consider two most frequently used hybrid amplifiers that can provide better performance.
The better q factor is provided by the raman amplifier 26. Raman amplifier is another important optical amplifier other than edfa. Wdm optical network analysis using edfa and raman amplifier. The raman gain profile may be expressed by the zero kelvin cross section as or by the thirdorder susceptibility tensor components as where is the effective area of the pump and signal overlapping region, is the stokes wavelength, and are the refractive indexes of fiber core at pump and stokes wavelengths, respectively, is the speed of light, is planks constant, and is the dielectric. Fiber raman amplifier is specially designed for amplification of optical signals in longdistance optical transmission systems and dense wavelength division multiplexed optical transmission systems, and can achieve high gain and low noise amplification for optical signals in cband or lband. Optical amplifiers use stimulated emission to amplify a optical signal, just as lasers. For example, semicon ductor laser amplifier can be constructed easily by. Applications for distributed raman amplification finisar corporation. This chapter describes the technologies needed for cascading an erbiumdoped fiber amplifier edfa and a fiber raman amplifier fra or ra to create a hybrid amplifier ha, the edfa raman ha. Edfa uses the principle of stimulated radiation of edf b er to. Erbium doped fiber amplifier edfa is an optical amplifier. Home forums fiber edfaraman hybrid amplifier gain edfaraman hybrid amplifier gain dennis jacq joined may 2016 participant hi guys, i am currently simulating edfaraman amplifier in terms of output gain base on the journal gain flattening of edfa using hybrid edfaraman amplifier with reduced channel spacing. 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.
Raman amplifiers for telecommunications selected topics. Finisar raman amplifiers can contain up to six pump laser. Raman amplification provides more flexibility than edfa. The only competitors to erbiumdoped fiber amplifiers in the 1. The hybrid module consists of a count\ erpropagating raman pump unit and a variable gain \vg\ edfa. Figure 9 typical raman amplifier configuration figure 10 illustrates the optical spectrum of a forwardpumped raman optical amplifier. Pdf performance configuration of ramanedfa hybrid optical. The second source of noise arises from the short upperstate lifetime of raman amplification, as short as 3 to 6 fs. Comparative performance of ramansoa and raman edfa.
White paper applications for distributed raman amplification. Raman gain can occur at any signal wavelength by proper choice of the pump wavelength. White paper introduction to optical amplifiers finisar corporation. Edfa uses the principle of stimulated radiation of edf fiber to amplify the. The pump laser is injected at the transmit end rather than the receive end as shown in figure 9. Boosting of an optical signal without any conversion of. At 50 km output power by edfaedfa and ramanedfa are 36. The claddingpumped multicore edfa is used to efficiently amplify signals in multiple cores simultaneously, while raman pumping is used to control loss in each core individually. In the distance range 40120 km, raman and edfa amplifier have compareable qfactor. Raman amplifier noise factor is defined as the osnr at the input of the amplifier to the osnr at the output of the amplifier. Edfa, semiconductor optical amplifier soa and fiber raman amplifier.
The simulated gff filter curve was designed aiming a flattened spectrum gain over all operation amplifier range. 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. Therefore it is used only for speciality applications. To compare performance of the hybrid amplifiers, the eye diagrams of detected signals were analyzed and the. For fibers with low drs noise, the raman noise figure due to ase is much better than the edfa noise figure. An optical signal can be amplified in the optical domain without being converted to electronic domain and back. After knowing the basic information of edfa and raman optical amplifiers, you must consider that the raman amplifier performs better for two main reasons. This hybrid edfara optical amplifier hoa is dual pumped. The optical signal is injected into this fiber, along with the light from a special pump laser that is designed to excite the erbium ions. Earlier, the lband edfa was used in combination with optical filters 45, raman amplifier, wavelength dependent splitters.
Edfa erbium doped fiber amplifier tutorial exfiber optical technologies co. Comparative performance of ramansoa and ramanedfa hybrid. The raman amplifier is typically much more costly and has less gain than anerbium doped fiber amplifier edfa amplifier. In many cases the raman and edfa modules are combined into a single hybrid ramanedfa module, thus reducing costs, streamlining and optimizing performance, and achieving unified realtime control of both units. For a more detailed discussion on the implementation of optical amplifiers using erbium doped fiber amplifier edfa technology see finisars white paper.
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