Hybrid Erbium-doped Fiber Amplifier Research Articles

Quantum-limited transmission distance of optically repeating systems using a hybrid EDFA/Raman-amplifier.

The transmission distance of optically repeating systems is ultimately bounded by quantum noises arising from attenuation and amplification. It is known that fiber Raman amplifiers (FRAs) can achieve longer quantum-limited distances than other amplification schemes owing to their distributed amplification characteristics. However, all-FRA systems are difficult to implement in practice. Therefore, a hybrid erbium-doped fiber amplifier (EDFA)/FRA system may be a reasonable solution for long-haul transmission. In this study, the quantum-limited transmission distance of hybrid EDFA/FRA systems is investigated. A formula for the quantum fluctuation variance during transmission was derived based on quantum mechanical treatment. Calculation results obtained with the derived formula quantitatively indicate that the quantum-limited transmission distance increases as the EDFA/FRA hybrid ratio varies from EDFAs alone to FRAs alone.

Enhanced triple-pass hybrid erbium doped fiber amplifier using distribution pumping scheme in a dual-stage configuration

An enhanced triple-pass hybrid optical fiber amplifier in a dual-stage configuration is presented by utilizing a combination of hafnium-bismuth erbium-doped fiber (HB-EDF) and bismuth erbium-doped fiber (Bi-EDF) as gain medium. The total Erbium-doped fiber length was only 199 cm, and both HB-EDF and Bi-EDF were forward pumped by 1480 nm with an optimum pump power of 170 mW and 110 mW, respectively to provide flat gain and wideband amplification. At high input power of -10 dBm, a flat gain of about 19 dB with gain fluctuation of less than 2 dB was observed over wideband ranging from 1555–1600 nm. On the other hand, the noise figure varied from 4.8–9.3 dB within the flat gain region. The triple-pass Erbium-doped fiber amplifier has been enhanced by utilizing distribution pumping scheme in the configuration. This improvised configuration minimised the cost of the amplifier yet having the comparable performance with the dual-pump configuration. A flat gain of 17.2 dB with the corresponding noise figure below 8 dB was obtained within 1555–1600 nm.

Suitability of FBG for Gain Flatness of 64 × 10 Gbps DWDM System Using Hybrid (EDFA+YDFA) Optical Amplifier in C + L Band up to 50 GHz (0.4 nm) Channel Spacing

Abstract Gain flatness of erbium-doped fiber amplifier (EDFA) is an important aspect to support high speed multimedia applications for smart devices, cloud computing, big data analysis and high definition television (HDTV) as it achieves equal power for all dense wavelength division multiplexing (DWDM) channels. In this paper, we compare 32 and 64 channels 10 Gbps DWDM system using hybrid EDFA+ Ytterbium-doped silica fiber amplifier (YDFA) in C + L band for 0.4, 0.8 and 1.6 nm wavelength spacing along with FBG for gain flattening. The system performance has been analyzed in terms of optical signal to noise ratio and spectral gain fluctuation observed from the optical power spectrums. It is observed that YDFA although extends the amplification window of EDFA from 1530 to 1610 nm (C to L band), but gain fluctuates over the operating wavelength range. Gain flatness is enormously improved (5–10 dB) by adding FBG as a gain flattening filter to the hybrid (EDFA+YDFA) amplifier. It is found that as the channel spacing decreases (from 1.6 to 0.4 nm) and the number of channels increases (from 32 to 64), the gain reduces due to inter-channel crosstalk and four wave-mixing effect.

Optical back propagation for fiber optic networks with hybrid EDFA Raman amplification.

We have investigated an optical back propagation (OBP) method to compensate for propagation impairments in fiber optic networks with lumped Erbium doped fiber amplifier (EDFA) and/or distributed Raman amplification. An OBP module consists of an optical phase conjugator (OPC), optical amplifiers and dispersion varying fibers (DVFs). We derived a semi-analytical expression that calculates the dispersion profile of DVF. The OBP module acts as a nonlinear filter that fully compensates for the nonlinear distortions due to signal propagation in a transmission fiber, and is applicable for fiber optic networks with reconfigurable optical add-drop multiplexers (ROADMs). We studied a wavelength division multiplexing (WDM) network with 3000 km transmission distance and 64-quadrature amplitude modulation (QAM) modulation. OBP brings 5.8 dB, 5.9 dB and 6.1 dB Q-factor gains over linear compensation for systems with full EDFA amplification, hybrid EDFA/Raman amplification, and full Raman amplification, respectively. In contrast, digital back propagation (DBP) or OPC-only systems provide only 0.8 ~ 1.5 dB Q-factor gains.

Performance analysis and comparison of multipump Raman and hybrid erbium-doped fiber amplifier + Raman amplifiers using nondominated sorting genetic algorithm optimization

This paper presents a performance analysis and comparison of optimized multipump Raman and hybrid erbium-doped fiber amplifier (EDFA) + Raman amplifiers, operating simultaneously at conventional (C) and long (L) bands, using multiobjective optimization based on evolutionary elitist nondominated sorting genetic algorithm. The amplifiers performance was measured in terms of on–off gain, ripple, optical signal-to-noise ratio (OSNR) and noise figure (NF), after propagating over 90 and 180 km of single-mode fiber (SMF). Numerical simulation results of the first analysis show that only three pumps are necessary to generate optimal gains in both amplifiers. Comparing the results of the second performance analysis, we conclude that, after 90 km SMF, the two amplifiers has the same on–off gain, if the total pump power (1807.1 mW) of the Raman amplifier is approximately double (100+994.7 mW) of the hybrid amplifier, when the EDFA is operating at 1480 nm with 5 m of doped fiber. Furthermore, the Raman amplifier needs a single laser with at most 741.1 mW, against 343.9 mW of the distributed Raman amplifier (DRA) pump in the hybrid system. Finally, the results of the last analysis, which considers only the EDFA + Raman amplifier, shows that with on–off gain of 26.14 dB, ripple close to 1.54 dB over a bandwidth of 66 nm and using three pumps lasers in the DRA the achieved OSNR was 39.6 dB with an NF lower than 3.3 dB, after 90 km of SMF.

Link Power Level Improvements in an Amplified 8-Channel CWDM System with Hybrid EDFA-SOA Pre-Amplifier

The link power improvement in a coarse wavelength division multiplexing (CWDM) system which is transmitted using a hybrid erbium-doped fiber amplifier (EDFA) and semiconductor optical amplifier (SOA) scheme as a pre-amplifier, is discussed. The network is designed for amplifying 8 CWDM channels ranging from 1471 nm to 1611 nm. The hybrid amplifiers’ gain measurement is obtained from experimental work with gain peak at 22 dB which is observed at 1531 nm. The amplifiers also caused power increment of 5.06 dB in the transmission link before the signal is split individually at the receiving end. Based on the higher gain peaks and power spectrum at 1531 nm and 1551 nm wavelengths, the proposed amplified link would be useful for the transmission of video applications.

Broadband C-plus L-band CW wavelength-tunable fiber laser based on hybrid EDFA and SOA

In this demonstration, we propose and experimentally investigate a widely C+L band wavelength-tunable fiber ring laser in continuous-wave (CW) tuning based on a hybrid semiconductor optical amplifier (SOA) and erbium-doped fiber amplifier (EDFA) in a serial scheme. When a hybrid first-stage SOA and second-stage EDFA is used inside ring cavity, the effectively amplification range can be extended from C-band to L-band. Here, the proposed laser features wide wavelength-tuning range, high output power, and high side-mode suppression ratio (SMSR). In addition, a tunable range over 91.5nm (from 1518.5 to 1610.0nm) has been achieved.

Impact of Raman Amplification on a 2-Tb/s Coherent WDM System

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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> 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.

16$\,{\times}\,$107-Gb/s 12.5-GHz-Spaced PDM-36QAM Transmission Over 400 km of Standard Single-Mode Fiber

Employing raised-cosine pulse-shaped polarization-division-multiplexing (PDM) 36 quadrature amplitude modulation (QAM) format and standard single-mode fiber (SMF-28), 16 × 107-Gb/s PDM-36QAM signals in 12.5-GHz spacing have been realized to transmit over 400 km with a hybrid erbium-doped fiber amplifier and Raman amplification. The spectral efficiency (SE) for the 100 Gb/s is up to 8 b/s/Hz. This is the longest transmission for 100 Gb/s with an SE of 8 b/s/Hz.

Optimal design for ultra-broad-band amplifier

We propose a novel hybrid genetic algorithm (GA) based on such techniques as clustering, sharing, crowding, and adaptive probability. The proposed GA can effectively solve multimodal optimization, including the global and local optima in the distributed multipump Raman amplifier (DMRA). The simulation results show that the optimal signal bandwidth Δ/spl lambda/ can be evidently broadened by means of increasing the number of pumps and that Δ/spl lambda/ decreases with the increase of Raman gain and the improvement of the flatness property. The optimal results show that the hybrid erbium-doped fiber amplifier and DMRA can availably overcome the weakness of pure DMRA and that both higher gain and broader bandwidth can be realized in hybrid amplifiers simultaneously.

Impact of hybrid EDFA-distributed Raman amplification on a 4 x 40-Gb/s WDM optical communication system

The impact of hybrid erbium-doped fiber amplifier-(EDFA) distributed Raman amplification on a high bit rate wavelength-division-multiplexed optical communication system is studied by means of a reliable simulation model that takes into account noise properties of Raman amplification. Pure Raman amplification allows the decrease of the mean input power of about 6 dB, keeping the bit error rate at the same level. The best performance, however, is obtained for loss compensation provided by hybrid EDFA/Raman amplifiers, due to the reduction of nonlinear distortion.

Low-Distortion and High-Output Optical Power Amplifier for Analog Transmission Employing Hybrid Erbium-Doped Fiber Configuration

We have proposed a novel configuration of erbium-doped fiber amplifier (EDFA) which realizes both a flat spectral gain and high output power for analog transmission. This EDFA uses hybrid EDF which consists of serially cascaded EDFs with different glass compositions, based on the fact that EDFs with certain glass compositions exhibit gain tilt of opposite signs in the wavelength range of interest. It is theoretically shown that, in the hybrid EDFA, the gain flattening under any required optical input/output conditions is possible without sacrificing output power by optimizing the constituent EDF lengths. By using thus designed hybrid EDFAs, 50-channel amplitude-modulated vestigial-sideband signals were successfully amplified in four stages with no significant degradation of signal distortions.

Performance analysis of self-synchronized optically preamplified PPM

The performance of a hybrid erbium-doped fiber amplifier pulse position modulation (EDFA PPM) system is investigated under self-synchronization. Sensitivity results are presented for a system operating at 622 Mb/s and /spl lambda/=1.53 /spl mu/m. These indicate that EDFA PPM offers 7.9 dB sensitivity improvement over an equivalent EDFA PCM system and is beyond the fundamental PCM limit. An original expression is derived for the EDFA PPM power spectral density (PSD) under jitter. Original results are presented for the timing variance and the jitter wrong slot error (JWSE) probability due to the extracted self-timing. An original analysis and results are given for the system sensitivity penalty due to jitter. The penalty varied between 0.15 and 1.9 dB for the range of parameters considered. The selection of the system parameters that minimizes the penalty is investigated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>