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Nonlinear Noise of Low Transmission Penalty Dual-Stage Discrete Raman Amplifier
摘要： We experimentally characterise the linear and nonlinear performance of a >70nm, dual-stage, 19.5dB average net gain discrete Raman amplifier using different nonlinear fibres in the second stage. We propose an architecture built with a combination of IDF and SMF, and compare its performance with amplifiers built with conventionally used nonlinear fibre types (IDF-IDF, IDF-DCF). The measured FWM product power shows the IDF-SMF architecture to generate less nonlinear interference when compared to other schemes. We test the amplifiers with 5x120Gb/s DP-QPSK WDM signals in a recirculating loop at 10 recirculations of 93.4km SMF fibre, where the power sweep shows up to 2dB optimum launch power difference, with the maximum Q2 factor varying by up to 1.6dB. Using the optimum transmission point we measure a Q2=8.8dB at 35 recirculations of 93.4km transmission (3269km) with the proposed IDF-SMF scheme, which is >460km further than the other tested architectures. All characterised schemes performed similarly in the linear noise regime.
关键词： Broadband Transmission,Discrete Raman Amplification,Nonlinearity Characterisation
更新于2025-09-23 15:21:21
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1.6 Micron Fiber Laser Source for CH <sub/>4</sub> Gas Leak Detection
摘要： We report on the development of a new pulsed fiber laser source at 1645.5 nm, based on stimulated Raman amplification. This laser source is intended to be used in a future lidar system, dedicated to methane gas leak monitoring in the vicinity of industrial facilities. In this paper we discuss reasons for choosing the 1645.5 nm wavelength, and then we present the two-stage amplification architecture of our fiber laser source under development. Recent experimental results and perspectives are drawn.
关键词： Raman amplification,fiber laser,methane gas leak detection,lidar
更新于2025-09-23 15:19:57
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Compression of laser pulses by near-forward Raman amplification in plasma
摘要： We propose a new scheme for compression of ultrashort laser pulses enabled by Near-Forward Raman Ampli?cation (NFRA) in plasma. In contrast to traditional forward Raman ampli?cation in plasma, the seed pulse in NFRA propagates faster than the pump through manipulation of the spatiotemporal properties of the pump beam. A “p-pulse” solution similar to that of stimulated Raman backscattering ampli?cation is obtained, indicating that NFRA can be used for compression of ultrashort laser pulses. NFRA is numerically demonstrated with a 2D simulation using a front-tilt near-forward pump pulse.
关键词： Raman amplification,plasma,laser pulses,pulse compression
更新于2025-09-16 10:30:52
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Optical Amplifiers - A Few Different Dimensions || Raman Fiber Laser–Based Amplification in Telecommunications
摘要： The chapter demonstrates a detailed study of Raman fiber laser (RFL)-based amplification techniques and their applications in long-haul/unrepeatered coherent transmission systems. RFL-based amplification techniques are investigated from signal/noise power distributions, relative intensity noise (RIN), and fiber laser mode structures. RFL-based amplification techniques can be divided into two categories according to the fiber laser generation mechanism: cavity Raman fiber laser with two fiber Bragg gratings (FBGs) and random distributed feedback (DFB) Raman fiber laser using one FBG. In addition, in cavity fiber laser–based amplification, reducing the reflectivity near the input helps mitigate the signal RIN, thanks to the reduced efficiency of the Stokes shift from the second-order pump. To evaluate the transmission performance, different RFL-based amplifiers were optimized in long-haul coherent transmission systems. Cavity fiber laser–based amplifier introduces >4.15 dB Q factor penalty, because the signal RIN is transferred from the second-order pump. However, random DFB fiber laser–based amplifier prevents the RIN transfer and therefore enables bidirectional second-order pumping, which gives the longest transmission distance up to 7915 km. In addition, using random DFB laser-based amplification achieves the distance of >350 km single mode fiber in unrepeatered DP-QPSK transmission.
关键词： Raman fiber laser,Raman amplification,coherent transmission,cavity fiber laser,random fiber laser
更新于2025-09-12 10:27:22
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74.38 Tb/s Transmission Over 6300 km Single Mode Fibre Enabled by C+L Amplification and Geometrically Shaped PDM-64QAM
摘要： Ultrawide-bandwidth optical amplification over almost 90 nm, covering the C+L bands, is described. Complemented by system-tailored geometrical constellation shaping and nonlinearity compensation, it enabled a record capacity transmission of 74.38 Tb/s over 6,300 km of G.654 single-mode fibre. The hybrid scheme, combining backward Raman pre-amplification with EDFA, significantly improves the average effective noise figure across the entire bandwidth, allowing the use of span lengths of 70 km. The system-tailored GS-64QAM constellation was optimised to both linear link impairments and transceiver nonlinearities, improving the gap to the AWGN channel capacity relative to square 64QAM from 0.6 bit/symbol to 0.35 bit/symbol. We experimentally evaluated the system performance using the bit-wise achievable information rate (AIR) and signal-to-noise ratio (SNR) at the end of transmission, as well as post SD-FEC BER.
关键词： geometric constellation shaping,nonlinear compensation,Erbium-doped fibre amplifier,Raman amplification,Broadband C+L band transoceanic transmission
更新于2025-09-11 14:15:04
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Design, Characterization, and Test of a Versatile Single-Mode Power-Over-Fiber and Communication System for Seafloor Observatories
摘要： A power-over-fiber (PoF) and communication system for extending a cabled seafloor observatory is demonstrated in this contribution. The system allows the cabled seafloor observatory to be linked, through a single optical fiber, to a sensor node located 8 km away. The PoF system is based on an optical architecture in which power and data propagate simultaneously on the same single-mode fiber. The Raman scattering effect is exploited to amplify the optical data signals and leads to the minimization of the sensor node power consumption. Versatile low power electronic interfaces have been developed to ensure compatibility with a wide range of marine sensors. A low-consumption field-programmable gate array and an energy-efficient microcontroller are used to develop the electronic interfaces. For an electrical input power of 31 W, up to 190 mW is recovered at the sensor node while a data bitrate of up to 3.6 Mb/s is achieved. The PoF system has been tested and validated for turbidity and acoustic measurement applications. The current study focuses on the electronic development and the validation of the PoF system.
关键词： Raman amplification,Low power embedded systems,power-over-fiber (PoF),seafloor observatories,remote sensing
更新于2025-09-10 09:29:36