Optical fiber communication system is an active research area for its high demand especially in the long-haul communication system. A lot of work has been done to improve the optical transmission system (OTS) as a long-haul system using remotely-pumped Erbium-Doped Fiber Amplifier (R-EDFA) and Distributed Raman Amplication (DRA). Despite these achievements, there is still room for enhancements and developments to solve the existing system's problems. This work presents a thorough research on OTS using hybrid R-EDFA and DRA approach. The research work includes gain enhancing technique under low pump powerm enhanced dispersion compensating technique, new R-EDFA location-optimization technique, and a figure of merit is introduced to determine the optimal setting of R-EDFA with respect to its practical applications (Post- and Pre-amplifier). Various designs for low pump R-EDFA configuration, in which a Chirped Fiber Bragg Grating (CFBG) is placed inside the R-EDFA configuration, is demonstrated in this research work. This configuration offers two functions at the same time, where it can achieve both double-pass amplification technique as well as dispersion compensating technique. A comparative analysis is conducted to compare the performance of the newly developed configuration with the conventional R-EDFA configurations, this configuration is found to give better performance compared to the conventional amplifier configurations, where a gain of 23 dB is achieved for input signal power of less than -35 dB at only 10 mW pump power. Since the location of R-EDFA has a high impact on the total transmission distance, a new technique is proposed to find the optimum location of R-EDFA, where a location close to the receiver is found to give a longer distance. In this research workm many configurations of OTS are developed and presented. A maximum transmission distance of 293 km is achieved using an optimized OTS which utilizes dual-function R-EDFA at 2.5 Gbps. A bit error rate (BER) ise used as the main performance parameter with a threshold value of better than 10-10. In addition to that, a mathematical modeling for this optimized configuration is carried out in this research work, which deals with the post- and pre-length of the system as well as the R-EDFA and DRA. Finally, in order to evaluate further the performance of the optimized configurations with respect to the previous systems, a new performance parameter called Pump Power Consumpstion (PPC) is introduced. This optimized OTS configuration has a better PPC (0.682 mW/km) compared to the previous OTS.

Master's Thesis from the year 2019 in the subject Instructor Plans: Computing / Data Processing / IT / Telecommunication, , course: M.Tech, language: English, abstract: With the evolvement of high speed and long-distance data communication systems, conventional band erbium-doped fiber amplifiers (C-EDFAs) are getting more attention in recent times. Major advantage of the C-band EDFA is that it provides the user to realize a system with wide bandwidth of 40 nm. But, from the reported works, it is evident that for Gain enhancement in C-band using EDFA is reported with the use of multiple stages, multiple pumps, Gain flattening filters etc. However, these techniques suffered from high cost, complex techniques, and low performance. Here enhancement process was done through the narrowband Fiber Bragg Gratings (FBG) or fiber reflectors mirrors. In this work, a conventional band erbium doped fiber amplifier is proposed with high gain and less noise figure by incorporating the two fiber bragg gratings (FBGs) for amplified spontaneous noise reinjection. Maximum ASE is emerged at 1565 nm for the at -55 dBm carrier powers. Maximum gain is found out to be 48.16 dB with noise figure of 5.29 dBm. Fiber amplifiers are crucial and fast-growing field in the communication system. The study of this field show that the formulation procedures of lasers generation and amplifier amplification displays a problematical process due to the factors affecting and changing amplifier and laser significances in a dynamic way. Gain, noise figure, wavelength, power flatness and power output are directly affected by any element or parameter inside the amplifier configuration. The design parameters such as: erbium ions concentration, EDF length, isolators, wavelength division multiplexing (WDM) position, pump power position, circulators, pump directions, all of these elements and factors are affecting directly the amplifier output. EDFA is an amplifier that is best used because of its low loss and high gain. For communication, there are two windows 1530-1560nm(C-band) and 1560-1610nm (L-band).

How is light amplified in the doped fiber? How much spontaneous emission noise is generated at the output? Do detectors with optical preamplifiers outperform avalanche photodiodes? What are the current types and architectures of amplifier-based systems? These are just a handful of the essential questions answered in Erbium-Doped Fiber Amplifiers: Principles and Applications, the first book to integrate the most influential current papers on this breakthrough in fiber-optics technology. Written by one of the pioneers in the field, this unique reference has become an essential reference for telecommunication professionals. This new paperback edition provides researchers, engineers, and system designers with detailed, interdisciplinary coverage of the theoretical underpinnings, main characteristics, and primary applications of EDFAs. Packed with information on important system experiments and the best experimental results to date as well as over 1,400 references to the expanding literature. Book jacket.

Research Paper (postgraduate) from the year 2019 in the subject Instructor Plans: Computing / Data Processing / IT / Telecommunication, , course: M.Tech, language: English, abstract: Fiber amplifiers are a crucial and fast-growing field in the communication system. The study of this field show that the formulation procedures of lasers generation and amplifier amplification displays a problematical process due to the factors affecting and changing amplifier and laser significance in a dynamic way. Gain, noise figure, wavelength, power flatness and power output are directly affected by any element or parameter inside the amplifier configuration. The design parameters such as: erbium ions concentration, EDF length, isolators, wavelength division multiplexing (WDM) position, pump power position, circulators, pump directions, all of these elements and factors are affecting directly the amplifier output. EDFA is an amplifier that is best used because of its low loss and high gain. For communication, there are two windows 1530-1560nm(C-band) and 1560-1610nm (L-band).

The exponential increase of communication bandwidth demand is giving rise to the so-called 'capacity crunch' expected to materialize within the next decade. Due to the nonlinear limit of the single mode fiber predicted by the information theory, all the state-of-the-art techniques which have so far been developed and utilized in order to extend the optical fiber communication capacity are exhausted. The spatial domain of the lightwave links is proposed as a new degree of freedom that can be employed to increase the number of transmission paths and, subsequently, overcome the looming 'capacity crunch'. Therefore, the emerging technique named space-division multiplexing (SDM) is a promising candidate for creating next-generation optical networks. To realize SDM in optical fiber links, one needs to investigate novel spatially integrated devices, equipment, and subsystems. Among these elements, the SDM amplifier is a critical subsystem, in particular for the long-haul transmission system. Due to the excellent features of the erbium-doped fiber amplifier (EDFA) used in current state-of-the-art systems, the EDFA is again a prime candidate for implementing practical SDM amplifiers. However, since the SDM introduces a spatial variation of the field in the transverse plane of the optical fibers, spatially integrated erbium-doped fiber amplifiers (SIEDFA) require a careful design. In this thesis, we firstly review the recent progress in SDM, in particular, the SDM optical amplifiers. Next, we identify and discuss the key issues of SIEDFA that require scientific investigation. After that, the EDFA theory is briefly introduced and a corresponding numerical modeling that can be used for simulating the SIEDFA is proposed. Based on a home-made simulation tool, we propose a novel design of an annular based doping profile of few-mode erbium-doped fibers (FM-EDF) and numerically evaluate the performance of single stage as well as double-stage few-mode erbium-doped fiber amplifiers (FM-EDFA) based on such fibers. Afterward, we design annular-cladding erbium-doped multicore fibers (MC-EDF) and numerically evaluate the cladding pumped multicore erbium-doped fiber amplifier (MC-EDFA) based on these fibers as well. In addition to fiber design, we fabricate and characterize a multicore few-mode erbium-doped fiber (MC-FM-EDF), and perform the first demonstration of the spatially integrated optical fiber amplifiers incorporating such specialty doped fibers. Finally, we present the conclusions as well as the perspectives of this research. In general, the investigation and development of the SIEDFA will bring tremendous benefits not only for future SDM transmission systems but also for current state-of-the-art single-mode single-core transmission systems by replacing plural amplifiers by one integrated amplifier.

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