Pumped Erbium Doped Fiber Amplifier Research Articles

Switchable wide-band multi-wavelength fiber laser via Brillouin random lasing resonance

A switchable wide-band multi-wavelength Brillouin-erbium fiber laser constructed by a sub fiber loop (SFL) containing an erbium-doped fiber amplifier (EDFA) and a main fiber cavity (MFC) including a 1-km length of high nonlinear fiber (HNLF) via Brillouin random lasing resonance is proposed and experimentally investigated. The EDFA is incorporated into the sub fiber loop to boost optical power of the externally injected Brillouin pump (BP) light and Stokes wave fed back from the MFC, and the amplified BP light and Stokes wave are forward launched into the HNLF via the SFL, meanwhile, the generated Stokes wave is partially backward injected into the HNLF via the MFC, which make the Brillouin random lasing resonance of the Stokes wave form in the laser cavity. Using the proposed scheme, up to 19-orders backward-output Brillouin Stokes lines with a peak power discrepancy of less than 10 dB, and 281 stable forward-output Brillouin Stokes lines with a peak power discrepancy of less than 30 dB are obtained from the different output ports of the laser. Compared with the previous results, the backward generated Brillouin Stokes lines increase from 11 to 19 orders and the spectral-lines compositions also happen to change, and the forward generated stable Brillouin Stokes lines span over 30 nm and are extended by more than 18 nm. It is obvious that the generated Brillouin Stokes lines significant increasing should owe to the Brillouin random lasing resonance being introduced into the laser cavity. Influences of the system parameters including the BP power, EDFA pump power, and feedback power of Stokes wave on the laser lasing are investigated in detail. The proposed multi-wavelength fiber lasers can backward generate switchable Brillouin Stokes lines from 1st order to 19th order with an increasing wavelength number in turn, only by adjusting the EDFA pump power; moreover, the wavelength interval of the backward generated Brillouin Stokes lines can be switched between double- and single-Brillouin frequency shift, only by adjusting feedback power of the Stokes wave, without adding additional system configuration. A statistical analysis for the randomness of the multi-wavelength Brillouin-erbium fiber lasers is also done.

Comparison of semiconductor lasers at wavelength 980 nm & 1480 nm using InGaAs for EDFA pumping scheme

Long distance Optical Communications are affected by many problems; loss of signal is one of them. Erbium Doped Fiber Amplifier (EDFA) is the key to solve it. By using Semiconductor Laser as pumping source for EDFA, the signal can brought back the performed of EDFA into normal condition. EDFA has a good wavelength operation at 980nm & 1480nm, in that case Semiconductor Laser using InGaAs at 980nm & 1480nm is suitable for them. By using selected wavelength and materials, the Semiconductor Laser can be produced properly. Also, determining the parameter is the important things to construct the Laser. By using Rate Equation, the performed of Semiconductor Laser can obtained several result. Those are injection current as a function of voltage, carrier density, photon density and output power as a function of injection current.

Comparison of semiconductor lasers at wavelength 980nm & 1480nm using InGaAs for EDFA pumping scheme

Long distance Optical Communications are affected by many problems; loss of signal is one of them. Erbium Doped Fiber Amplifier (EDFA) is the key to solve it. By using Semiconductor Laser as pumping source for EDFA, the signal can brought back the performed of EDFA into normal condition. EDFA has a good wavelength operation at 980nm & 1480nm, in that case Semiconductor Laser using InGaAs at 980nm & 1480nm is suitable for them. By using selected wavelength and materials, the Semiconductor Laser can be produced properly. Also, determining the parameter is the important things to construct the Laser. By using Rate Equation, the performed of Semiconductor Laser can obtained several result. Those are injection current as a function of voltage, carrier density, photon density and output power as a function of injection current.

Computer Model for EDFA Dynamics Over 1525–1560 nm Band Using a Novel Multi-Wavelength MATLAB Simulink Test Bed for 8-Channels

ABSTRACTA novel erbium-doped fibre amplifier (EDFA) test bed is designed using the dominant technical MATLAB Simulink platform to characterize gain, noise figure and amplified spontaneous emission (ASE) power variations of a forward pumped EDFA operating as functions of amplifier length, injected pump power, signal input power and doping density in the C-band (1525–1560 nm). The numerical modelling of the rate and propagation equations is done. The Simulink model for two-level-based analysis is designed to investigate the dynamic characteristics of an EDFA. A significant addition to the model is the ability to handle multiple channels using the absorption and emission coefficients that vary as per different specifications and the quantum well laser is being modelled to be applied as the pump source. The results are shown and analyzed graphically for designated simulation environment that accurately represents EDFA performance metrics such as gain, population inversion factor , noise figure, quantum conversion efficiency and power conversion efficiency. The present model can be implemented successfully as a test bed to study the EDFA dynamics over the entire third optical communication bandwidth (1525–1690 nm) with the ability to analyze and optimize all the parameters to achieve the desired operating performance before actual physical designing of device as per the application.

Optimized radiation-hardened erbium doped fiber amplifiers for long space missions

In this work, we developed and exploited simulation tools to optimize the performances of rare earth doped fiber amplifiers (REDFAs) for space missions. To describe these systems, a state-of-the-art model based on the rate equations and the particle swarm optimization technique is developed in which we also consider the main radiation effect on REDFA: the radiation induced attenuation (RIA). After the validation of this tool set by confrontation between theoretical and experimental results, we investigate how the deleterious radiation effects on the amplifier performance can be mitigated following adequate strategies to conceive the REDFA architecture. The tool set was validated by comparing the calculated Erbium-doped fiber amplifier (EDFA) gain degradation under X-rays at ∼300 krad(SiO2) with the corresponding experimental results. Two versions of the same fibers were used in this work, a standard optical fiber and a radiation hardened fiber, obtained by loading the previous fiber with hydrogen gas. Based on these fibers, standard and radiation hardened EDFAs were manufactured and tested in different operating configurations, and the obtained data were compared with simulation data done considering the same EDFA structure and fiber properties. This comparison reveals a good agreement between simulated gain and experimental data (<10% as the maximum error for the highest doses). Compared to our previous results obtained on Er/Yb-amplifiers, these results reveal the importance of the photo-bleaching mechanism competing with the RIA that cannot be neglected for the modeling of the radiation-induced gain degradation of EDFAs. This implies to measure in representative conditions the RIA at the pump and signal wavelengths that are used as input parameters for the simulation. The validated numerical codes have then been used to evaluate the potential of some EDFA architecture evolutions in the amplifier performance during the space mission. Optimization of both the fiber length and the EDFA pumping scheme allows us to strongly reduce its radiation vulnerability in terms of gain. The presented approach is a complementary and effective tool for hardening by device techniques and opens new perspectives for the applications of REDFAs and lasers in harsh environments.

Dynamics of Stokes Waves and Pulses Generated by Stimulated Brillouin Scattering in a Resonator Including Highly Nonlinear Fiber

We experimentally and theoretically investigate the generation of Stokes waves and the dynamics of pulses produced by cascaded stimulated Brillouin scattering (SBS) in a resonator, including a highly nonlinear fiber (HNLF) and an in-cavity erbium-doped fiber amplifier (EDFA) forming a multi-wavelength Brillouin erbium-doped fiber laser system. Using coupled wave equations with the Brillouin pump, Stokes and acoustic waves, propagation in the presence of the SBS and optical Kerr effect, the modeled system simulates the evolution of participating pump and Stokes waves to verify the experimental results. The dependence of the number of generated Stokes waves on EDFA pump and Brillouin pump powers is studied showing that the proper simultaneous change (increase or decrease) of the two pump powers over few hundred of milliwatts (using the power design diagram) results in generating the same number of Stokes waves reaching steady state. Dynamics of the interference signal at the resonator output are also presented for a long HNLF (33 m) showing strong instability due to the existence of a few longitudinal modes within the SBS gain bandwidth with the possibility of random mode hopping. For a short HNLF (3 m), a single longitudinal mode operation is possible and the stability of generated pulses is expected but still depends on the phase relationships per round trip of the participating pump and Stokes waves. A good consistency between simulation and experiment is found.

Effective use of an EDFA and Raman pump residual powers via a Bi-EDF in L-band multi-wavelength fiber laser generation

Residual powers of an erbium-doped fiber amplifier (EDFA) and a Raman pump are utilized effectively for pumping a 0.45 m long bismuth-based EDF (Bi-EDF) in linear-cavity L-band multi-wavelength fiber laser generation. A 7.7 km dispersion compensating fiber (DCF) operates as both Brillouin and Raman gain media and a 6.5 dBm fixed-power tunable laser source (TLS) amplified by an EDFA works as a Brillouin pump (BP). By inserting the Bi-EDF in the linear cavity and using the EDFA and the fixed Raman pump residual powers 13.6 mW and 64 mW, at wavelengths 978.8 nm and 1490.6 nm respectively, the gain spectrum is inhomogeneously broadened so that linewidth of the gain spectrum is expanded from 3.4 to 12.3 nm. As a result, the number of lines of an L-band multi-wavelength fiber laser (MFL) is increased noticeably. In addition, the number of lines at a BP wavelength 1590.6 nm decreased from 38 to 32 by using the maximum EDFA pump residual power of 44 mW due to a reduction in the quantum coefficient efficiency. However, flatness and stability characteristics of the MFL are improved. The MFL can be generated in the wavelength region 1570–1610 nm with the signal to noise ratio of about 42.

Performance of Brillouin optical time domain reflectometer with erbium doped fiber amplifier

The performance of Brillouin optical time domain reflectometry (BOTDR) affected by different pump power and direction of erbium doped fiber amplifier (EDFA) is experimentally demonstrated. A temperature error of 0.5°C and spatial resolution of 10m is obtained over 80km sensing fiber with EDFA. The temperature resolution and dynamic range of BOTDR with backward pumped EDFA is better than forward pumped EDFA. Within the range of pump power, the resolution of BOTDR can be improved by increasing pump power.

High-energy, in-band pumped erbium doped fiber amplifiers

We have demonstrated and compared high-energy, in-band pumped erbium doped fiber amplifiers operating at 1562.5 nm under both a core pumping scheme (CRS) and a cladding pumping scheme (CLS). The CRS/CLS sources generated smooth, single-peak pulses with maximum pulse energies of ~1.53/1.50 mJ, and corresponding pulse widths of ~176/182 ns respectively, with an M2 of ~1.6 in both cases. However, the conversion efficiency for the CLS was >1.5 times higher than the equivalent CRS variant operating at the same pulse energy due to the lower pump intensity in the CLS that mitigates the detrimental effects of ion concentration quenching. With a longer fiber length in a CLS implementation a pulse energy of ~2.6 mJ is demonstrated with a corresponding M2 of ~4.2. Using numerical simulations we explain that the saturation of pulse energy observed in our experiments is due to saturation of the pump absorption.

Optimizing the pumping configuration for the power scaling of in-band pumped erbium doped fiber amplifiers

A highly efficient (~80%), high power (18.45 W) in-band, core pumped erbium/ytterbium co-doped fiber laser is demonstrated. To the best of our knowledge, this is the highest reported efficiency from an in-band pumped 1.5 µm fiber laser operating in the tens of watts regime. Using a fitted simulation model, we show that the significantly sub-quantum limit conversion efficiency of in-band pumped erbium doped fiber amplifiers observed experimentally can be explained by concentration quenching. We then numerically study and experimentally validate the optimum pumping configuration for power scaling of in-band, cladding pumped erbium doped fiber amplifiers. Our simulation results indicate that a ~77% power conversion efficiency with high output power should be possible through cladding pumping of current commercially available pure Erbium doped active fibers providing the loss experienced by the cladding guided 1535 nm pump due to the coating absorption can be reduced to an acceptable level by better coating material choice. The power conversion efficiency has the potential to exceed 90% if concentration quenching of erbium ions can be reduced via improvements in fiber design and fabrication.

Gain and Noise figure performance of erbium doped fiber amplifiers (EDFAs) and Compact EDFAs

In this paper, we compare the Gain and Noise figure characteristics of physical EDFAs and Compact EDFAs in an optical system consisting of cascade of both the amplifiers. We demonstrate the gain, noise figure variations of a forward pumped EDFA and Compact EDFAs as functions of Er 3+ fiber length, injected pump power and up-conversion co-efficient. It is observed that the gain becomes constant when the length of both the amplifiers reaches above 20 m. The comparison shows that the higher gain with flatter output is obtained in case of Compact EDFAs than Physical EDFAs in a system consisting of chain of both the amplifiers. It is further investigated that the agreement between the Compact and Physical EDFA models is good up to 10 m with the no up-conversion co-efficient. Also, the noise figure obtained in case of Physical EDFA is higher than Compact EDFAs when same amplifier length is more than 20 m and then becomes constant for both the amplifiers.

Gain and Noise Figure Performance of Erbium-Doped Fiber Amplifiers

Fiber loss is a fundamental limitation in realizing long haul point–to-point fiber optical communication links and optical networks. One of the advanced technologies achieved in recent years is the advent of erbium doped fiber amplifiers (EDFAs) that has enabled the optical signals in an optical fiber to be amplified directly in high bit rate systems beyond Tetra bits. In this paper, a simulation of an EDFA has been studied to characterize Gain, Noise Figure of a forward pumped EDFA operating in C band (1525-1565 nm) as functions of Er+3 fiber length, injected pump power, signal input power and Er+3 doping density. The simulation has been done by using Optisystem 5.0 software simulator (license product of a Canadian based company) at bit rate 10 Gbps.

The L-band EDFA of high clamped gain and low noise figure implemented using fiber Bragg grating and double-pass method

The L-band erbium-doped fiber amplifier (EDFA) of low noise figure and high clamped-gain using gain-clamped and double-pass configuration is presented in this paper. A total of five different configurations of EDFAs by reflection scheme with single forward pumping schemes are examined and compared here. Among these configurations, we first find the configuration of 1480-nm pumped L-band EDFA with optimum gain and noise figure value. To further minimize the gain variation, a fiber Bragg grating (FBG) with 1615-nm center wavelength and 1-nm bandwidth is determined and added in double-pass L-band EDFA. The gain variation and maximum noise figure of EDFA while channel dropping is investigated. As the number of channel dropping from 32 to 4, the L-band type-A EDFA keep the variation of gain within 2.9dB and the maximum noise figure below 5dB with each channel’s input power of −23dBm.

Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration

A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge.

Experimental Study of Lasing Characteristics of Brillouin/Erbium Optical Fiber Laser

A lasing charactrization of a Brillouin/erbium optical fiber laser (BEFL) is experimentally discussed. In the BEFL, an erbium-doped fiber amplifier (EDFA) is incorporated into the Brillouin laser resonator to enhance small Brillouin gain, which makes the configuration of the Brillouin laser resonator easy and flexible. The experimental results show that the output power of the BEFL has a threshold against the Brillouin pump power, and above the Brillouin threshold, the output power increases linearly with the EDFA pump'power. The BEFL threshold decreases with increasing the length of the optical fiber in the laser resonator used as a Brillouin gain medium. The BEFL oscillates in a stable single longitudinal mode because the bandwidth of the Brillouin gain profile is very narrow (∼ 30 MHz). The relative intensity noise (RIN) and the spectral lineshape were measured. The noise floor level decreases with increasing the EDFA pump power, and the full-width at half maximum of the BEFL was measured to be about 8 kHz.

Spectral beam combining of a single-mode 980-nm laser array for pumping of erbium-doped fiber amplifiers

With a view to improve the power level and brightness of semiconductor pump lasers, we have resorted to a scalable implementation and achieved spectral beam combining through a low-quality-factor external cavity. For that purpose, a high-power single-mode laser array emitting up to 2.1 W at 3.2 A at 980 nm has been realized, which delivers 1.5 W in external cavity. A power of 0.66 W was finally coupled into the single-mode fiber, with a coupling efficiency of 44%. Pumping experiments of an erbium-doped fiber amplifier utilizing this laser have demonstrated efficiency and noise characteristics similar to what is usually obtained with conventional sources, with the noteworthy advantage of a lower gain excursion over the C-band.

Simulink model for EDFA dynamics applied to gain modulation

Bononi and Rusch (1998) developed an approach for investigating erbium-doped fiber amplifier (EDFA) dynamics based on the one-dimensional ordinary nonlinear differential equation derived by Sun et al. (1996) for the time-dependent population of excited-state erbium atoms in EDFAs. Bononi and Rusch then applied their approach to the investigation of transients (1998). In this paper, we implement the same nonlinear ordinary differential equation as a MATLAB Simulink model and we use harmonic and random-noise inputs to investigate gain modulation, referred to also as overmodulation. This is the low-frequency (/spl sim/kHz) amplitude modulation of the EDFA pump and the communication signal used for propagating line monitoring information [(Freeman and Conradi, 1993), (Murakami et al., 1996), (Shimizu et al., 1993), (Gieske and Bystrowski, 2001)]. Freeman and Conradi (1993) showed that the EDFA transfer function from overmodulated pump to output communication signal was effectively a low-pass filter response. They also showed that the transfer function from overmodulated communication input signal to output signal was effectively a high-pass filter response similar to a lead compensator with one zero followed in frequency by one pole. They developed a numerical model (Freeman and Conradi, 1993) to predict the shape of these transfer functions and compared their predictions with experiment. However, their model was not sufficiently developed in Freeman and Conradi (1993) to be directly applicable to the design of line monitoring systems. Using a Simulink simulation of the nonlinear differential equation due to Sun et al. (1996) and using standard signal processing techniques for calculating the pump-to-signal and signal-to-signal transfer functions, we obtain the low-pass filter response to pump overmodulation and the high-pass filter response to signal overmodulation. We compare our results with experiment for a given set of EDFA parameters (Gieske and Bystrowski, 2001). Our approach is straightforward and easy to implement as a MATLAB Simulink model.

1.48-μm-wavelength ASM-DC-PBH LDs with extremely uniform lasing characteristics

High-power 1.48-/spl mu/m erbium-doped fiber amplifier pumping InGaAsP MQW laser diodes (LDs) have been investigated using all selective metal-organic vapor phase epitaxy grown (ASM) fabrication method. The method provided a precise dimension control of multiquantum-well active layers and current blocking layers, resulting in excellent current blocking characteristics and extremely uniform lasing characteristics even at high injection current. The average light output power of 262 mW at 1 A with a standard deviation of as small as 1.4 mW for 20 consecutive LDs has been achieved.

Comparative study on temperature-dependent multichannel gain and noise figure distortion for 1.48- and 0.98-μm pumped EDFAs

Temperature dependence of multichannel gain flatness and noise figure (NF) was compared for different pump wavelengths of 1.48 and 0.98 /spl mu/m on silica-based erbium-doped fiber amplifiers (EDFAs) through measurement-based numerical simulation. Owing to its temperature sensitive pump emission cross section, the 1.48-/spl mu/m pumping showed greater temperature sensitivity (maximum 0.75-dB gain flatness distortion with 0.57-dB average gain level shift, 0.3-dB NF variation for 25/spl deg/C change) than the 0.98 /spl mu/m pumping (maximum 0.5-dB gain flatness distortion with 0.015-dB average gain level shift, 0.05-dB NF variation for 25/spl deg/C change). However, it was also found that distortion ripple spectra mainly coming from the changes of signal cross sections and asymmetric gain temperature dependence necessitate compensation techniques in the EDFA link, irrespective of pump wavelength.

SUPER PON-a fiber to the home cable network for CATV and POTS/ISDN/VOD as economical as a coaxial cable network

A complete super PON fiber to the home cable network as economical as the classic coaxial cable network, designed for application in the local loop is presented. The concept uses high power lasers, remote pumped erbium doped fiber amplifiers (EDFAs) to reduce cost by high splitting ratio, economical receivers for the downstream direction and economical CD player lasers for the upstream direction. Several novel technical solutions for this application (a new method to avoid stimulated Brillouin scattering (SBS), remote pumping of the EDFA and a compensating technique to adapt the CD laser to the normal fiber) are presented.