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. In this paper, the effect of the large signal power on the raman amplification is simulated utilizing optisystem. Calculations and measurements of raman gain coefficients. Unlike the edfa and soa the amplification effect is achieved by a nonlinear interaction between the signal and a pump laser within an optical fiber.
Calculations and measurements of raman gain coefficients of different fiber types 1 chapter 1 introduction 1. Although raman ampli cation in optical bers was observed as. We demonstrated a high power yb raman combined nonlinear fiber amplifier. 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. And the output power stability can be guaranteed by atc and apc circuits. For a particular use, the decision has to be made about which amplifier to be used. Dispersion analysis of fiber raman amplifier for wdm system. Some of the pump wavelengths may be selected to create raman gain in this range. A splicedtogether fiber amplifier configuration is much more resistant to environmental disturbances than its bulkoptical counterpart. Simulation of distributed raman amplification dra for fiber based transmission systems raman spectroscopy. Edfa erbium doped fiber amplifier tutorial exfiber optical technologies co. Unlike erbiumdoped fiber amplifiers edfas, where the gain spectrum is constant and determined by the. 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.
Raman fiber amplifiers are provided in which multiple pump wavelengths are used. With the help of the formula, the effect of the pumping scheme on the srs suppression of the. Again, the transmission fiber can hardly be optimized for raman amplification, as the propagation losses need to be low, and the pump light is also subject to propagation losses. A raman fiber amplifier may be used to amplify optical signal channels over a range of wavelengths. Raman amplifiers for telecommunications selected topics. Schematic diagram of the all fiber raman amplifier based on a mopa configuration with a piece of grin fiber a, all the optical components in the measuring system b and the refractive index profile of the grin fiber c. Gain and noise performance of fiber raman amplifiers. High power ybraman combined nonlinear fiber amplifier. For example, if the nominal raman gain of the amplifier for a given fiber type is 15 db, then a discrete loss point of 0. Fiber amplifiers and fiber lasers based on stimulated raman.
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. The raman optical amplifier is based on an entirely different principle than edfas or conventional lasers. The mars series raman fiber amplifier has well designed builtin drive circuit and logical control circuit. Index termscoherent communications, distributed ampli fiers, optical fiber amplifiers, optical fiber communications, optical fiber networks, raman scattering. Other pump wavelengths may be selected to create raman loss in this range. The fiber gain media of the former is generally within 10 km. Applications for distributed raman amplification optical. Raman fiber amplifier using a wide bandwidth continuous wave pump field of the invention this invention pertains to raman amplifiers and, more particularly, to raman amplifiers utilizing a wide bandwidth continuous wave cw overall power spectrum pump signal. Thus, an up to 100fold increase in pump power combined with up to a tenfold increase in raman gain coefficient leads to a renewed interest in raman amplification in an all fiber configuration.
The ratio between the power of amplified spontaneous emission and the power of incoherent optical noise is quantitatively determined by detailed analysis of experimental data in the pump powers range. Pdf simulation and experimental validation of gain. White paper applications for distributed raman amplification. Calculations and measurements of raman gain coefficients of. Osa 25 w ramanfiberamplifierbased 589 nm laser for. Raman amplifier such as fiber type, fiber length, pump power and gain coefficient for enhancement the gain of fiber raman amplifier. Highefficiency allfiber raman fiber amplifier with record output power yizhu chen, jinyong leng, hu xiao et al. In a fra, the optical signal is amplified due to stimulated raman scattering srs. Pdf this work presents a study to obtain the gain and noise figure of fiber raman amplifiers fras by the two coupled equations of. The optical amplifier defined in claim 1 further comprising a control unit, wherein the raman pump wavelengths produced by the raman pump create a gain spectrum in the raman pumped fiber and wherein the gain spectrum is adjusted in real time by using the control unit to control the raman pump. Fiber raman amplifier fra fiber raman amplifier fra is also a relatively mature optical amplifier. Boosting of an optical signal without any conversion of the. Rotatingpolarization coherent antistokes raman spectroscopy.
Distributed fiber raman amplifiers dfras are well known to reduce the noise generation and to smooth the signal level variation along the link. Raman amplifier and optical transmission system us20050024716a1 en 20030715. Kilowattlevel ybraman fiber amplifier with narrowlinewidth and neardiffractionlimited beam quality pengfei ma, yu miao, wei liu, daren meng, and pu zhou college of advanced interdisciplinary studies, national university of defense technology, changsha, hunan, 410073, peoples republic of china email. Rp photonics encyclopedia raman amplifiers, fiber amplifier.
Kilowattlevel ybraman fiber amplifier with narrowlinewidth. Edfa vs raman optical amplifier fiber optic cables solutions. Mar 05, 2018 raman amplifier noise factor is defined as the osnr at the input of the amplifier to the osnr at the output of the amplifier. Jan 04, 2012 in a distributed raman amplifier, the optical fiber link itself is used as the amplification medium. A silica fiber raman amplifier pumped at a wavelength of 1451. This data source is applied to a driver with nrz format. In general, fra can is divided into lumped type called lra and distributed type called dra. Recent citations kilowattlevel ytterbium raman fiber amplifier with a narrowlinewidth and neardiffractionlimited beam quality pengfei ma et aloctavespanning, continuouswave supercontinuum generation with record. Raman ampli cation is an accepted technique for enhancing system performance. Background of the invention 1 o optical fiber technology is currently utilized in. It consists of little more than a highpower pump laser, usually called a raman laser, and a wdm or directional coupler.
Pdf gain and noise performance of fiber raman amplifiers. It consists of a highpower pump laser and fiber coupler optical circulator. Raman fiber amplifiers fiber optic essentials wiley. Pdoped fiber offers a raman shifted gain that is three times higher than the germaniumdoped fibers. In a distributed raman amplifier, the optical fiber link itself is used as the amplification medium. In the pursuit of progress, several kinds of optical amplifiers are published to enhance the signals. Highefficiency allfiber raman fiber amplifier with record. Mostly, all optical amplifiers are used in optical communication. Analytical study on the stimulated raman scattering threshold.
Osa 25 w ramanfiberamplifierbased 589 nm laser for laser. The seed is a 30 w dualwavelength ybdoped fiber laser formed by 1070 nm and 1120 nm lasers. Noise figure analysis of distributed fibre raman amplifier g. In this paper, the stimulated raman scattering srs threshold of the distributedpumped fiber amplifier consisting of multiple subamplifiers is analytically studied based on the rateequation model. The formation dynamics of the optical noise in a silica single mode fiber smf as function of the pump power variation in the counter pumped fiber raman amplifier fra is experimentally studied. For special applications requiring higher pump power, a six pump standalone unit with removable hotswappable pump laser drawers is available. Woburn, massachusetts, 2003 and other private writings. The optical amplification occurs in the transmission fiber itself. Dec 30, 2014 generally, brillouin type amplifier is not used in optical communication. Raman amplification in optical communication systems dtu orbit. The dra noise and signal gain is distributed over the span fibers effective length. In the most common application a two or three pump module provides up to 850mw raman pump power and up to 18db raman onoff gain for g. The influences of various parameters of the laser on 2nd order raman threshold and maximum output power are. Optical device with immediate gain for brightness enhancement of optical pulses.
Dfb sends pulse to check any back reflectionthat exists in the. The ratio between the power of amplified spontaneous emission and the power of incoherent optical noise is quantitatively determined by detailed analysis of experimental data. Boosting of an optical signal without any conversion of. Pdf we report on a 25 w continuous wave narrow linewidth 95% coherent beam combination of two.
New pumping methods and materials are also improving the performance of raman amplifiers. Dispersion analysis of fiber raman amplifier for wdm. Thus, an up to 100fold increase in pump power combined with up to a tenfold increase in raman gain coefficient leads to a renewed interest in raman amplification in an allfiber configuration. Pdf raman fiber amplifier with integrated cooler galina. Amplifier performance polarization extinction ratio 15 db at max. Raman amplifiers for telecommunications selected topics in. The edfa amplifier is used inline amplifier on account of its compatibility. Introduction raman effect principles of the raman fiber amplifier noise in raman amplifiers applications of raman fiber amplifiers. The amplification medium is the span fiber in a distributed type raman amplifier dra. Generally, brillouin type amplifier is not used in optical communication. On the other hand, raman fiber amplifier rfa will be a very good power amplifier because of its high saturation. The srs threshold formula is presented where the predictions agree well with the numerical results.
We demonstrated a high power ybraman combined nonlinear fiber amplifier. We report on a 25 w continuous wave narrow linewidth 95% coherent beam combination of two narrow linewidth erbium doped fiber amplifier tutorial exfiber optical technologies co. The raman fiber amplifier rfa is operated by the thirdorder nonlinear effect of the strong laser in the fiber stimulated raman scattering srs. In a raman amplifier, the signal is intensified by raman amplification. The main application is to produce highpower sources at 1240 and 1480 nm that can be used as pump lasers in oband and cband fiber amplifiers respectively. Finisar raman amplifiers can contain up to six pump laser diodes, providing up to 2w raman pump power. A high power pump laser is injected at the far end and travels backward in the fiber to amplify. Highefficiency all fiber raman fiber amplifier with record output power yizhu chen, jinyong leng, hu xiao et al. We comprehensively study the effects of temporal and spectral optimization on singlemode raman fiber amplifiers. Raman amplifier and method of exciting a raman amplifier jp2005010212a en 20030616. Pdoped fiber offers a raman shifted gain that is three. A simplified block diagram of the finisar raman amplifier deployed in backward pumping configuration.
Raman amplifier worldwide leading supplier in fiber optic network, fttx, fiber cabling, fiber testing and integrated network solutions. However, the noise figure of the amplifier can be controlled by limiting the fiber lengths used and constructing multistage amplifiers, as has been shown in a 2. Two types of raman amplification systems are simulated. A raman amplifier is an optical amplifier based on raman gain, which results from the effect of stimulated raman scattering. As a result of this, another signal photon is produced, with the surplus energy resonantly passed to the vibrational states. Dstributed feedback dfb laser is a narrow spectral bandwith which is used as a safety mechanism forraman card. Recent citations kilowattlevel ytterbiumraman fiber amplifier with a narrowlinewidth and neardiffractionlimited beam quality pengfei ma et aloctavespanning, continuouswave supercontinuum generation with record. Rare earth doped fiber amplifiers erbium edfa 1500 nm, praseodymium. A raman optical amplifier is not a black box like an edfa.
For special applications requiring higher pump power, a. Advanced optical components raman fiber amplifier rfa. It can achieve highperformance output with carriergrade pump laser. The amplification medium is the span fiber in a distributed type raman amplifier. 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. Pdf 25 w ramanfiberamplifierbased 589 nm laser for laser. Another type of distributed amplifier is the raman amplifier, where no rare earth dopant is required, and stimulated raman scattering is used for amplification. Three types of fibers with different gain characteristics are used in our numerical simulations. The ramanactive medium is often an optical fiber, although it can also be a bulk crystal, a waveguide in a photonic integrated circuit. In this thesis, fiber raman amplifiers fras are investigated with the pur pose of. Raman amplifiers, in the encyclopedia of laser physics and technology. May 18, 2017 edfa vs raman optical amplifier although the fiber loss limits the transmission distance, the need for longer fiber optical transmission link seems never ending.
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