Brillouin effect characterization in all-Raman amplified 4 × 40 Gb/s WDM system (original) (raw)
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Microwave and Optical Technology Letters, 2010
This paper analyzes experimentally the limitations observed in lightwave systems using distributed Raman amplifiers operating under large pump power input conditions. The Brillouin effect is observed as the pump power becomes equal to 1 watt centered in a specific pump wavelength. The presence of Brillouin peaks degrades the system performance. The Raman amplifier is set with singlemode and dispersion compensating fibers and evaluated in a high capacity WDM link at transmission rates up to 40 Gb/s per channel. The dispersion compensation was accomplished by adjusting the length of the dispersion compensating fiber. The system and amplifier characterization were developed in terms of the on-off gain, ripple, optical signalto-noise ratio, eye diagram and extinction ratio.
Journal of Lightwave Technology, 2000
Benefits provided by higher order bidirectional Raman pumping schemes in 10-Gb/s unrepeated wavelengthdivision-multiplexing transmission systems are experimentally quantified in terms of BER performances at 10 Gb/s. By keeping under control double-Rayleigh-scattering-noise-induced transmission penalties, which can degrade system performance at very high ON-OFF Raman gain, as well as nonlinear propagation effects such as Brillouin scattering, self-and cross-phase modulations, four-wave-mixing, and Raman-induced crosstalks, we show a total unrepeated system reach enhancement up to 3.5 dB with respect to first-order bidirectional pumping. As confirmed by theory, the maximum reach enhancement is mainly limited by pump-to-signal relative intensity noise transfer induced by higher order copumping.
Experimental validation of double-pass discrete Raman amplifier limitation for large signals
IEEE Photonics Technology Letters, 2006
In this letter, we present a report on the experimental validation of double-pass discrete Raman amplifier (DRA) limitation for large signals. It has been proven that the limitation of double-pass Raman amplifier for large signals is due to stimulated Brillouin scattering (SBS) even though with a modulated signal at 10-Gb/s data. The multichannel amplification shows that this limitation can be relaxed due to energy distribution among the channels, the SBS threshold is enhanced. An average gain of 19.2 dB is obtained in four-channel amplification without any significant SBS effects. The double-pass DRA is found suitable for large signals to be deployed in wavelength division multiplexing systems.
Performance of WDM fiber-radio network using distributed Raman amplifier
IEEE Photonics Technology Letters, 2006
We investigate the impairment induced by stimulated Brillouin scattering (SBS) effect and noise characteristics of wavelength-division-multiplexing fiber-radio network assisted by distributed Raman amplifier (DRA) or erbium-doped fiber amplifier. Experimental results indicate that forward-pumping DRA can increase the link optical output power limited by SBS effect in downstream transmission and backward-pumping DRA can improve signal-to-noise ratio in upstream transmission, which is verified by binary phase-shift keying transmission experiments. Moreover, our experimental results show that DRA does not introduce additional impairment from interchannel crosstalk due to cross-phase modulation and degradation in spur-free dynamic range. Index Terms-Broad-band wireless access, distributed Raman amplifier (DRA) and crosstalk, fiber-radio.
Impact of Raman Amplification on a 2Tb/s Coherent WDM System
IEEE Photonics Technology Letters, 2011
The impact of hybrid erbium-doped fiber amplifier (EDFA)/Raman amplification on a spectrally efficient coherent-wavelength-division-multiplexed (CoWDM) optical communication system is experimentally studied and modeled. Simulations suggested that 23-dB Raman gain over an unrepeatered span of 124 km single-mode fiber would allow a decrease of the mean input power of ~6 dB for a fixed bit-error rate (BER). Experimentally we demonstrated 1.2-dB Q-factor improvement for a 2-Tb/s seven-band CoWDM with backward Raman amplification. The system delivered an optical signal-to-noise ratio of 35 dB at the output of the receiver preamplifier providing a worst-case BER of 2 × 10 -6 over 49 subcarriers at 42.8 Gbaud, leaving a system margin (in terms of Q -factor) of ~4 dB from the forward-error correction threshold.
Optics Express, 2005
We demonstrate a novel distributed fiber Raman amplified bus topology used for WDM transmission over 35 km of single-mode fiber by use of a multiwavelength Raman pump laser and eight Fiber Bragg gratings (FBGs). This topology reduces the number of addressing wavelengths needed at the head of the bus. Furthermore, by relocating the FBGs' wavelengths of a first section, it is obtained power transparency at the end of the overall bus, without requiring any additional pump source. We show how the topology allows the received powers from the first section sensors to be equalized and partially amplify the overall network. We investigate how the performance depends on the launched pump power. Results obtained with this new configuration are compared with those achieved in a previously reported optically amplified bus topology.
Optimization of pumping schemes for 160Gb/s single-channel Raman amplified systems
IEEE Photonics Technology Letters, 2004
Three different distributed Raman amplification schemes-backward pumping, bidirectional pumping, and second-order pumping-are evaluated numerically for 160-Gb/s single-channel transmission. The same longest transmission distance of 2500 km is achieved for all three pumping methods with a 105-km span composed of superlarge effective area fiber and inverse dispersion fiber. For longest system reach, second-order pumping and backward pumping have larger pump power tolerance than bidirectional pumping, while the optimal span input signal power margin of second-order pumping is the largest and gets 5-dB improvement compared to backward pumping. Span loss tolerance increased to 140 km with more than 2000-km reach. Optimal signal power variation at both ends of the span can provide about 6-dB positive net gain.
Full characterization of modern transmission fibers for Raman amplified-based communication systems
Optics Express, 2007
Telecommunication carriers have to estimate the Raman parameters of the fibers installed on their optical transport networks in order to facilitate the design of the next generation of high bit-rate Raman amplified-based transmission systems. This paper reports a very complete characterization of the most popular modern transmission fibers in terms of Raman efficiency, noise figure and double Rayleigh backscattering crosstalk. Our experiment is based on an averaged power analysis, applied to a counter-pumped long-haul distributed fiber Raman amplifier. We evaluate as well at 40 Gb/s for these different fiber types the double Rayleigh backscattering impact in terms of Q-factor penalty for various Raman gains and RZ modulation formats with different duty cycles.
Optics Express, 2017
We experimentally evaluate the influence of RIN transfer from pump to signal on the transmission performance of a 10 x 30 Gbaud DP-QPSK transmission system using a 2 nd-order ultra-long Raman fiber laser amplifier, considering the effect of cavity front-end reflectivity and forward pump power ratio. The evolution of the Q-factors with distance up to maximum reach is monitored for a 10 x 30 Gbaud DP-QPSK transmission system with WDM channels between 1542.94 nm to 1550.12 nm. A maximum transmission distance of 6479 km is found for configurations with low forward pump powers corresponding to the optimal balance between RIN and ASE impairments.