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We compare deploying additional optical amplification sites with deploying Raman pumps in existing sites to increase the capacity of 20-THz optical systems. Results show that deploying Raman pumps is a cost-effective solution to increase system capacity while equalizing the optical performance of transmitted bands.

Multiband (MB) optical fiber transmission systems can unlock additional capacity in existing optical fiber infrastructures, enabling them to keep up with the increase in traffic demand while postponing costly optical fiber deployments. However, due to the worse transmission characteristics of MB systems than C-band-only transmission, the network’s overall spectral efficiency decreases when increasing the transmission bandwidth. The extent of this performance degradation is paramount to determining the commercial viability of deploying MB systems. By estimating the generalized signal-to-noise ratio using the GNPy library, this work analyzes the impact of using counterpropagating Raman amplification to improve the performance of an S + C + L -band transmission system comprising a total bandwidth of 15.5 THz. Raman amplification is proposed to mitigate the worse system performance resulting from the stimulated Raman scattering effect and the worse noise figure of the S-band optical amplifier. We show that the optimized deployment of a counterpropagating Raman pump makes it possible not only to improve but also to equalize the network-wide optical performance of the S + C + L -band transmission system, which potentially reduces the complexity of routing and wavelength assignment algorithms. The capacity, spectral efficiency, and number of feasible lightpaths of the S + C + L -band system are compared with C- and C + L -band systems with and without Raman amplification on two reference networks. Results show that the spectral efficiency of the S + C + L -band system with Raman amplification is similar to the C-band-only system without Raman amplification. These results provide evidence that this strategy can be effectively used to compensate for the worse transmission characteristics of MB systems, the higher noise figure of the S-band optical amplifier, the SRS effect, and the additional losses from the band demultiplexer and coupler required at every amplification stage to separate the transmission bands. Overall, the simulation results highlight that a single optical fiber can approximately carry the same data when using a 15.5 THz transmission band (and Raman amplification) as three parallel fibers using C-band-only transmission (without Raman amplification).

Distributed Raman amplifier (DRA) has been widely studied in recent decades because of its low noise figure and flexible gain. In this paper, we present a novel scheme of DRA with broadband amplified spontaneous emission(ASE) source as pump instead of discrete pump lasers. The broadband pump is optimized by machine learning based inverse design and shaped by programmable waveshaper, so as to realize the ultrafine, dynamic and arbitrary gain spectrum shaping of Raman amplification. For the target of flat gain spectrum, the maximum gain flatness of 0.1086 dB is realized based on the simulation results. For the target of arbitrary gain spectrum, we demonstrate four gain profiles with maximum root mean square error (RMSE) of 0.074 dB. To further measure the performance of arbitrary gain spectrum optimization, the probability density functions (PDF) of RMSE and Errormax are presented. Meanwhile, the numeral relationship between the bands of broadband pump and signal is also explored. Furthermore, this work has great application potential to compensate the gain distortion or dynamic change caused by other devices in communication systems.

This project proposes the design of ultrafast communication circuit which can enable the high speed secured data transmission at 50 Gb/s and 100 Gb/s by the use of distributed Raman amplifier, EDFA (Erbium – doped fiber amplifier), filter, single mode fiber along with Fiber Bragg Grating (FBG) and attenuators. The simulation of the suggested optical circuit involves the use of parameters of Raman amplifier and EDFA and other components included in the optical structure. The design also includes the use of encryption and decryption techniques to ensure secured communication. Thus, realization of these circuits at 50 Gb/s and 100 Gb/s will enable the future optical communication applications for ultrafast data transmission to large distances.

Дипломна робота присвячена наддовгим волоконно-оптичним лініям зв’язку (ВОЛЗ) типу «Nothing in line» (NIL) з використанням оптичних підсилювачів Рамана на кінцевих пунктах прийому/передачі. Метою роботи прокладання нового шляху ВОЛЗ в Україні довжиною понад 300 км та розрахунок потрібних параметрів раманівських підсилювачів для ВОЛЗ типу NIL та інших елементів системи. У роботі приведено аналіз та детальний розрахунок параметрів підсилювача та підбір інших структурних елементів. Прокладання нового шляху ВОЛЗ в Україні було обрано для задоволення потреб населення та розроблено у вигляді карти. Розрахункова частина роботи була розрахована ручним методом, без використання сторонніх програм. Загальний обсяг роботи: 70 сторінок, 25 ілюстрацій, 5 таблиць, 20 посилань, 0 додатків The thesis is devoted with ultra-long fiber optic communication lines (FOCL) «Nothing in line» (NIL) type using Raman optical amplifiers at the endpoints of transmit/receive. The purpose of the work is the laying of a new path of FOCL in Ukraine with a length of 300 km and the calculation of the required parameters of Raman amplifiers for FOCL type NIL and other system elements. The analysis and detailed calculation of amplifier parameters and selection of other structural elements are presented in the paper. The laying of a new pathway for FOCL in Ukraine was chosen to meet the needs of the population and was developed as a map. The calculated bristle work was calculated by manual method, without the use of third-party programs. Total workload: 70 pages, 25 illustrations, 5 tables, 20 links, 0 applications.

We propose an embedded controller able to autonomously manage Raman amplification in software-defined optical networks. The conceived structure allows the system to work both in single and multi-band transmission, achieving a large range of amplification constraints. A set of experiments validates this proposal.

This paper presents a modification for the already consolidated analytical model that calculates the gain and ripple in multi-pump Raman amplifiers by considering energy conservation. The original analytical model precisely computes the pump-pump interaction to the C- and L-band for a WDM input signal. However, when this method is used to amplify a large bandwidth, as the entire C and a part of the L band, the increase in the number of pump lasers impacts the obtained results. The error, if compared with results obtained by a numerical method, becomes significant. An analysis in terms of energy is proposed to minimize the discrepancy between analytical and numerical results. An improvement is observed to the gain results.

We experimentally investigate the performance of a distributed Raman amplifier (DRA)-based pulse compressor for a phase modulated signal. A 10 Gb/s return-to-zero (RZ)-differential phase shift keying (DPSK) signal is compressed to picosecond range after transmission. Pulsewidth is continuously compressed in a wide range from 20 to 3.2 ps by changing the pump power of the DRA while the compressed waveforms are well-matched with sech2 function. Error-free operations at bit-error-rate (BER) of 10-9 are achieved for the compressed signals of various pulsewidths with low power penalties within 2.3 dB compared to the back-to-back. After the compression, the 10 Gb/s signal is used to generate a 40 Gb/s RZ-DPSK optical time division multiplexing (OTDM) signal. This 40 Gb/s OTDM signal is then successfully demultiplexed to 10 Gb/s DPSK signal by using an optical gate based on four-wave mixing (FWM) in a highly nonlinear fiber (HNLF).

We demonstrate the wavelength conversion of return-to-zero differential phase-shift keying (RZ-DPSK) signal with the pulsewidth-tunable operation using a Raman amplifier (RA)-based ultrashort pulse compressor and a highly nonlinear fiber (HNLF)-based four-wave mixing (FWM) switch. The wavelength of the input RZ-DPSK signal is converted to new wavelengths owing to the FWM effect in HNLF. On the other hand, the pulsewidth of the wavelength-converted RZ-DPSK signal is tuned from 10 to 3 ps by using the ultrashort pulse source based on RA-based adiabatic soliton pulse compression. The bit error rate characteristics of the input RZ-DPSK and the wavelength-converted RZ-DPSK signals with different pulsewidths are measured and error-free operations are achieved in all cases. The optical spectra, autocorrelation traces, and clear and opening eye diagrams show high conversion performance with wide-range pulsewidth tunability.

We describe a hybrid Raman-optical parametric amplifier (HROPA) operating at the O- and E-bands and designed for coarse wavelength division multiplexed (CWDM) passive optical networks (PONs). We present the mathematical model and simulation results for the optimization of this HROPA design. Our analysis shows that separating the two amplification processes allows for optimization of each one separately, e.g., proper selection of pump optical powers and wavelengths to achieve maximum gain bandwidth and low gain ripple. Furthermore, we show that the proper design of optical filters incorporated in the HROPA architecture can suppress idlers generated during the OPA process, as well as other crosstalk that leaks through the passive optical components. The design approach enables error free performance for all nine wavelengths within the low half of the CWDM band, assigned to upstream traffic in a CWDM PON architecture, for all possible transmitter wavelength misalignments (±6 nm) from the center wavelength of the channel band. We show that the HROPA can achieve error-free performance with a 170-nm gain bandwidth (e.g., 1264 nm–1436 nm), a gain of &gt, 20 dB and a gain ripple of &lt, 4 dB.

We consider the networking benefit of selectively upgrading line optical amplifiers to Hybrid Erbium/Raman solution to reduce the number of optical-electrical-optical regenerators. We consider two different network topologies and eleven different hybrid amplification solutions.

Optimal design of a Raman-amplified periodic cell depends strongly on the constraints set by overall system requirements. The best possible tradeoff in terms of cost-effectiveness, nonlinearity, pumping efficiency, optical signal-to-noise ratio (OSNR), and tolerance to relative intensity noise transfer varies depending on characteristics, such as total transmission length, desirable number of spans or power budget requirements. Here, we perform a thorough experimental and theoretical study of the best performing configurations for second-order amplification over a broad range of applications, with span lengths ranging from 10 to 150 km. Results highlight the presence of different regimes in which different contributions to noise become dominant. We find that ultralong Raman fiber laser cells with high forward pumping are to be preferred in unrepeatered transmission applications, whereas in long-haul transmission a shorter cell based on random distributed feedback lasing can be a better option as it enables low relative intensity noise transfer with a higher output OSNR at the cost of a reduced pumping efficiency

Nowadays, optical amplifiers designs are induced by new requirements generated by optical networks. The introduction of WDM reconfigurable networks with increasing rate from 10-40 Gb/s to 100 Gb/s and beyond, demand new optical amplifiers development with improved gain spectral flatness and noise figure for all operational range of input powers and set-point gains. In this paper, it was developed a hybrid distributed Raman/EDFA amplifier with a novel hybrid gain control (HGC) scheme based on joint actuation. The HGC was firstly developed by numerical simulation and after experimentally, in a WDM system with 100 km SSMF fiber span and full C-band load. The Results shows an improved equivalent noise figure with flattened gain spectrum for all amplifier operation range in dynamic optical networks.

Tento dokument je zaměřen na simulaci a analýzu S-band multi-vlnových délek výkonného Ramanova laseru Brillouine s využitím vláken Bragg a Ramanového zesilovače v kruhové dutině. Raman zesilovače se používají pro zesílení signálu průměrného výkonu modelu. This paper is focusing on simulation and analyzing of S-band multi-wavelength Brillouine Raman fiber laser performance utilizing fiber Bragg grating and Raman amplifier in ring cavity. Raman amplifier average power model is employed for signal amplification

We propose a low-cost Raman based amplification scheme for coarse wavelength division multiplexing systems. We also present a mathematical model suitable to be used in the design, analyze and optimization of Raman amplification systems. We validate the mathematical model with extensive comparisons with experimental results. Good agreement is obtained between numerical and experimental results. An amplification system offering more than 18 dB of gain over more than 80 nm is obtained using only four low power (up to 500 mW) semiconductor lasers. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 297–301, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23075

Mūsdienās optiskās šķiedras ir piedzīvojušas strauju attīstību un aizvien plašāk tiek pielietotas telekomunikācijās. Viena no aktuālam tematikām ir esošo sakaru sistēmu sasniedzama pārraides attāluma palielināšana, pielietojot kombinētos optisko signālu pastiprināšanas risinājumus. Ar datorsimulāciju palīdzību šajā darbā tika realizētas 16 kanālu DWDM pārraides sistēmas ar SOA un Ramana-SOA optisko signālu pastiprināšanas risinājumiem. Tika novērtēta uztverto optisko signālu kvalitāte, un tika secināts ka kombinēta risinājuma izmantošana ļauj sasniegt lielāku signāla-trokšņu attiecību.

In this report we introduced a 10Gbit/s 16 channel DWDM transmission system with NRZ-OOK modulation format and 50 GHz channel spacing, supplemented it with a single in-line distributed Raman amplifier 72 km away from the transmitter block and compared Co and Counter-propagating pumping by obtaining the maximal transmission distance.

In this work, the O-band discrete Raman amplifier gain bandwidth optimization using genetic algorithm of a commercial simulator is carried out. The main objective of the study was to optimize the wide Raman amplifier gain bandwidth obtaining values of gain variation less than 0.5 dB. Using a fiber DCF (Dispersion Compensating Fiber) as Raman amplifier medium, the pump number was varied and the gain variation for each pump configuration has been verified. For a fixed 70 nm (1275-1345 nm) bandwidth consisting of 62 signal frequencies points, the results were generated for one, two, three, four, five, six, seven and eight backward pumps, which with the last one it was obtained the best result of 0.35 dB gain variation. In addition to this analysis, it was also found the Raman amplifier noise figure for this band and made a brief comparison with the conventional profile bands. Neste trabalho a otimização da largura de banda de ganho de um amplificador Raman discreto na banda "O" utilizando algoritmo genético de um simulador comercial foi realizada. O objetivo principal do trabalho foi otimizar a maior largura de banda de ganho do amplificador Raman obtendo valores de variação de ganho menores que 0.5 dB. Utilizando uma fibra DCF (Dispersion Compensating Fiber) como meio de ganho do amplificador Raman, o número de bombeio foi variado e a variação de ganho para cada configuração de bombeio foi verificada. Para uma largura de banda fixa em 70 nm (1275-1345 nm) compreendendo 62 pontos de freqüências de sinal, foram gerados resultados para um, dois, três, quatro, cinco, seis, sete e oito bombeios contrapropagantes sendo que com esta última configuração foi obtido o melhor resultado de variação de ganho de 0.35 dB. Além desta análise, também foi verificado o perfil da figura de ruído do amplificador Raman nesta banda e feita uma breve comparação com o perfil em bandas convencionais.

This thesis deals with extremes statistics which has become an attractive subject in optics since a comparison with oceanic rogue waves has been proposed at the end of 2007. We report some potential mechanisms stimulating the rogue wave formation in the context of guided propagation of light in optical fibers. In a first part, we explore optical rogue waves in supercontinuums generated by fourth-order modulation instability and we propose a stabilization method based on the use of two continuous seeds. Then, we present a detailed study on Raman fiber amplifiers where we determine the conditions of emergence of giant structures : in presence of a partially incoherent pumping wave, a quasi-instantaneous gain combined with a low walk-off lead to extremes statistics. We have validated these conditions for a continuous wave as well as a pulse train. Conclusions have also been successfully extended to a parametric amplifier based on incoherent second-order modulation instability. In the last part, a turbulent system is studied as a function of incoherence and we identify three regimes. In one of these regimes, we highlight the existence of intermittent quasi-solitons. Finally, we are interested in nonlinear structures called Akhmediev Breathers which present compression-decompression cycles and we focus our attention on its asymptotic limit: the Peregrine soliton. It corresponds to a very interesting prototype of rogue waves. Our experimental work, performed at optical communication wavelength and using several methods of spectro-temporal characterization, is complemented by numerical and analytical studies., Ce mémoire présente des travaux portant sur les ondes aux statistiques extrêmes qui représentent un sujet extrêmement attractif en optique depuis qu’une comparaison avec les vagues scélérates océaniques a été proposée fin 2007. Nous décrivons donc les mécanismes de formations de ces structures extrêmes dans le cadre de la propagation guidée de la lumière dans les fibres optiques. Dans une première partie, nous commençons par explorer les ondes scélérates optiques dans les supercontinuums générés par instabilité modulationnelle d’ordre 4 et proposons une méthode de stabilisation basée sur l’utilisation de deux germes continus. Puis, nous continuons avec une étude approfondie sur les amplificateurs Raman à fibre où des conditions d’apparitions des structures géantes sont déterminées. En effet, en présence d’une pompe partiellement incohérente comme le laser Raman fibré, un gain quasi-instantané et un faible walk-off mènent à des statistiques extrêmes. Cela a pu être vérifié que le signal soit continu ou impulsionnel et dans le cadre d’un amplificateur paramétrique basé sur l’instabilité modulationnelle d’ordre 2 incohérente. Dans la dernière partie, un système turbulent est étudié en fonction de l’incohérence ce qui nous a permis d’identifier trois régimes avec, en particulier, le second où il existe des quasi-solitons intermittents. Enfin, nous nous intéressons à des structures non-linéaires appelées Breathers d’Akhmediev, qui présentent des cycles de compression-décompression, et portons notre attention sur leur limite asymptotique : le soliton de Peregrine. Ce dernier est vu comme un prototype très intéressant des vagues scélérates. Nos études expérimentales, menées aux longueurs d’ondes des communications optiques et utilisant différentes méthodes de caractérisations spectro-temporelles, sont complétées par des études numériques et analytiques.

International audience; Long optical similaritons using a Raman fibre amplifier are generated. These pulses, with a highly parabolic profile, are monitored in real time on a high speed oscilloscope. Tunability of both the temporal and spectral widths of the pulses is then investigated.

This thesis presents a novel technique named "Core Suction" for fabricating optical fiber preforms for manufacturing highly doped fibers (HDFs) for optical amplification (Raman effect based or Erbium fiber based). The technique involves drawing the molten non-conventional core glass material into the silica cladding tube to form the preform. The developed technique is simple, inexpensive and shows great potential for fabricating preforms of highly nonlinear non-conventional multi-component glasses as the core material. Preforms were made with various core glasses such as Schott SF6, Lead-Tellurium-Germanate, Lead-Tellurium-Germanate- Neodymium -Erbium and MM2 in silica cladding tubes and then pulled into fibers. The fabricated fibers were measured for refractive index profile, loss spectrum and spontaneous Raman spectra. Elemental analysis of the fiber samples was also performed using an electron microprobe. Erbium doped fiber amplifiers (EDFAs) were setup using 30 cm, 5cm and 1 cm lengths of fabricated erbium doped fibers and their gain spectra measured. The distributed gain spectrum for an EDFA was also measured using an optical frequency domain reflectometery (OFDR) technique. Commercial dispersion compensated fiber (DCF) with very high GeO2 doping was used to setup a Raman amplifier and the gain spectrum measured. One of the needs of Raman amplification in optical fibers is to predict an accurate Raman gain, based on the fiber's refractive index profile. A method of predicting Raman gain in GeO2 doped fibers is presented and the predicted Raman gain values are compared with the measured ones in the same fibers. Raman gain issues like the dependence of the Raman gain on the GeO2 concentration, polarization dependence were taken into account for the gain calculations. An experimental setup for Raman gain measurements was made and measurement issues addressed. Polarization dependence of the Raman gain in one kilometer of polarization maintaining fiber was also measured. Ph. D.

One can use stimulated Raman scattering to obtain a near-diffraction-limited Stokes beam from a multimode