28 research outputs found
High-capacity multi-span transmission performance characterization of broadband discrete Raman amplifier
The performance of a multi-span transmission link compensated with a >75nm broadband discrete Raman amplifier is experimentally evaluated using multiple DP-x-QAM modulation formats over a multi-channel C + L band WDM grid with up to 182 ×50 GHz spaced channels
Hybrid discrete Raman/EDFA design for broadband optical amplification in metro WDM systems
A novel design of a broadband discrete Raman/EDFA hybrid amplifier is proposed. A broadband signal of 84 channels across 75 nm is experimentally amplified and the gain contribution of each amplifier stage is shown. The amplifier consists of a discrete Raman amplifier using a DCF fibre pumped at three 14×× nm wavelengths, which is followed by a 1480 nm pumped erbium doped fibre. An average gain of 15.4 dB and gain flatness of ± 1.7 dB with no gain equalising elements is achieved
Impact of pump-signal overlap in S+C+L band discrete Raman amplifiers
We experimentally investigate the impact of pump-signal overlap in ultra-wideband (>13THz) Raman amplifiers and measure the transmission penalty on 30GBaud PM-QPSK signals due to adjacent Raman pumps in a 15dB gain, 150nm (∼18.8THz) S+C+L-band discrete Raman amplifier. We present an efficient numerical model to predict the performance penalty induced by crosstalk from Rayleigh backscattered light from backward-propagating Raman pumps showing good agreement with the experimental results. A 4nm guard-band must be retained around an overlapping Raman pump based on typical, commercial semiconductor laser pump diodes to ensure a negligible transmission penalty in S-ban
Low penalty, dual stage, broadband discrete Raman amplifier for high capacity WDM metro networks
We present a broadband (>70nm), dual stage, discrete Raman amplifier built with small and standard core fibre with ~19.5dB net gain. We transmit 120Gb/s DP-QPSK signals over 3040km with 38 amplifications for a preFEC BER<3.8×10-3
Characterisation of Linear and Nonlinear Noise of a Dual-Stage Broadband Discrete Raman Amplifier
The linear and nonlinear noise performance of a 70nm, dual-stage, ∼20dB-gain discrete Raman amplifier is characterised experimentally using different second-stage fibres. An advantageous IDF-SMF configuration is identified with an improvement in the nonlinear performance by >1dBQ 2 compared with IDF-DCF configurations
Linear and Nonlinear Noise Characterisation of Dual Stage Broadband Discrete Raman Amplifiers
We characterise the linear and nonlinear noise of dual stage broadband discrete Raman amplifiers (DRAs) based on conventional Raman gain fibres. Also, we propose an optimised dual stage DRA setup that lowers the impact of nonlinear noise (generated in the amplifier) on the performance of a transmission link (with 100-km amplifier spacing). We numerically analyse the design of a backward pumped cascaded dual stage 100-nm DRA with high gain (∼20 dB) and high saturated output power (>23 dBm). We show that the noise figure (NF) of the dual stage DRA is mainly dominated by the first stage irrespective of the type of gain fibre chosen in the second stage, and we also demonstrate that optimising the length and the type of Raman gain fibre can have significant impact on the size of inter/intrasignal nonlinearities generated. Here, we report a theoretical model to calculate the nonlinear noise power generated in transmission spans with dual stage DRAs considering piecewise signal power evolution through the Raman gain fibres. The predicted signal-to-noise ratio (SNR) performances are calculated from the combined contributions from NF and nonlinear product power obtained using the proposed analytical model for transmission systems deployed with 100-km transmission span compensated by different dual stage DRAs. Finally, an optimised IDF 6 km-SMF 10 km dual stage configuration has been identified using the theoretical model, which allows maximum SNR of 14.6 dB at 1000 km for 1 THz Nyquist wavelength division multiplexed signal and maximum transmission reach of 3400 km at optimum launch power assuming 8.5 dB HD-FEC limit of the Nyquist PM-QPSK signal
Nonlinear Noise of Low Transmission Penalty Dual-Stage Discrete Raman Amplifier
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
RIN-penalty mitigation and transmission performance improvement using forward propagated broadband first order Raman pump
We demonstrate that using a broadband pump enables forward-propagated first order distributed Raman amplification by mitigating RIN-associated penalty. This extends the reach of 10 × 120 Gb/s DP-QPSK WDM transmission up to 7499 km, compared with other commercially available pumps. Moreover, using this Raman scheme maintains uniform/symmetric signal power distribution and requires low pump power
Performance characterization of high gain, high output power and low noise cascaded broadband discrete Raman amplifiers
In this paper, gain, noise and nonlinear performance characterization of cascaded broadband discrete Raman amplifiers with different gain fibre combinations is presented. We numerically demonstrate the design of a backward-pumped cascaded dual stage broadband (∼70 nm) discrete Raman amplifier with high gain (∼19 dB), low noise (∼ 6 dB noise figure) and lower nonlinear penalty by optimizing two different types of gain fibres
Bismuth doped fibre amplifier operating in Eand S- optical bands
Bismuth-doped fibre amplifiers offer an attractive solution for expanding the bandwidth of fibre-optic telecommunication systems beyond the current C-band (1530-1565 nm). We report a bismuth-doped fibre amplifier in the spectral range from 1370 to 1490 nm, with a maximum gain exceeding 31 dB, and a noise figure as low as 4.75 dB. The developed system is studied for forward, backward, and bi-directional pumping schemes and three different signal power levels. The forward pumping scheme demonstrates the best performance in terms of the achieved noise figure. The developed amplifier can be potentially used as an in-line amplifier with >20dB gain in the spectral band from 1405 to 1460 nm