Performance Of Erbium-doped Fiber Amplifier Research Articles

Robust low-noise 795-nm single-frequency fiber laser with continuous frequency tuning

This study presents a highly efficient and low-noise all-fiber single-frequency (SF) 795-nm laser system realized using a simple and robust single-pass frequency-doubling configuration. The foundation of the system is a 1590-nm erbium-doped fiber amplifier operating in a master oscillator power amplifier configuration seeded by a distributed feedback semiconductor laser at 1590.52 nm. The main amplifier exhibits an exceptional amplification efficiency of 30.5 %. By utilizing a periodically poled lithium niobate waveguide, the 795-nm laser is frequency-doubled with an output power reaching 2.3 W, corresponding to an optical efficiency of 44 % of the fundamental laser. Crucial to its application in precision measurements and quantum technologies, the SF 795-nm laser exhibits a relative intensity noise close to −150 dBc/Hz in the frequency range of 0.1 to 10 MHz. Additionally, a continuous frequency-tuning range of 11.7 GHz is achieved by modulating the current with a 2.5-mA 1-Hz triangular wave. Notably, this is the first report on an all-fiber SF 795-nm laser system.

Experimental–Simulation Analysis of a Radiation Tolerant Erbium-Doped Fiber Amplifier for Space Applications

Research on optical amplifiers has highlighted how ionizing radiation negatively impacts the performance of erbium-doped fiber amplifiers (EDFAs), through the degradation of their gain. The amplitudes and kinetics of this degradation are mainly explained by the radiation-induced attenuation (RIA) phenomenon at the pump and signal wavelengths. In this work, the gain degradation of a radiation tolerant EDFA (exploiting a cerium-co-doped active optical fiber) induced by ionizing radiation up to 3 kGy (SiO2), at two dose rates, 0.28 Gy/s and 0.093 Gy/s, is studied through an experimental/simulation approach. Using a home-made simulation code based on the rate and power propagation equations and including the RIA effects, the radiation-dependent performance of EDFAs were estimated. The variations in the spectroscopic parameters caused by irradiation were also characterized, but our results show that they give rise to EDFA gain degradation of about 1%. To overcome the issue of overestimating the RIA during the radiation tests on the sole active rare-earth-doped fiber, a new RIA experimental setup is introduced allowing us to better consider the photobleaching mechanisms related to the pumping at 980 nm. A good agreement between experimental and simulated gain degradation dose dependences was obtained for two different irradiation conditions, thus also validating the simulation code for harsh environments applications.

The influence of Kerr nonlinear effect on the signal and pump intensities in parabolic and triangular index EDFAs

Erbium-doped fiber amplifiers (EDFAs) is an integral part of all-optical communication system. Intensities of pump and signal within EDFAs is one of the significant parameters in its application perspective. Nonlinear effect on pump and signal may affect the performance aspect of EDFAs. In this work, we study intensity profile of pump and signal at different wavelengths of interest in EDFAs for the first higher order (LP11) excited mode considering the nonlinear impact. In this comparative analysis, EDFAs made up of some parabolic-index and triangular-index fibers of several V-numbers have been chosen. Our study involves the power series expression of the LP11 field prescribed by Chebyshev’s technique. A short computation is needed for achieving the objective by this method. Outcomes of this exercise are in superb conformity with those derived through the cumbersome finite element method (FEM) proving reliability of the Chebyshev’s method. The analysis is important in the context of use of dual mode optical fiber in EDFAs. The impact of Kerr nonlinearity on the performance of EDFAs involving dual mode optical fiber is also investigated. This analytical exercise through a handy and reliable mathematical instrument may be a dependable option for photonic EDFAs designers in practical realization of nonlinear EDFAs.

Doping radius effects on an erbium-doped fiber amplifier

In an erbium-doped fiber amplifier (EDFA), erbium ions act as a three-level system. Therefore, much higher pump energy is required to achieve the population inversion in an erbium-doped fiber (EDF). This higher pump energy requirement complicates the efficient design of an EDFA. However, efficient use of the pump power can improve the EDFA performance. The improved performance of an EDFA can be obtained by reducing the doping radius of the EDF. A smaller doping radius increases pump–dopant interactions and subsequently increases the pump–photon conversion efficiency. Decreasing the doping radius allows a larger proportion of dopant ions, which are concentrated near the core, to interact with the highest pump intensity. However, decreasing the doping radius beyond a certain limit will bring the dopant ions much closer and introduce detrimental ion–ion interaction effects. In this Letter, we show that an optimal doping radius in an EDF can provide the best gain performance. Moreover, we have simulated the well-known numerical aperture effects on EDFA gain performance to support our claim.

A Comprehensive Study on EDFA Characteristics: Temperature Impact

In this paper, a comprehensive study on erbium-doped fiber amplifier (EDFA) characteristics under temperature variation has been performed. The rate and propagation equations that characterize EDFA performance pumped at 980 nm and 1480 nm in the forward direction are solved numerically. The Boltzmann distribution between the pump and the gain wavelength is taken into account, and is found to be effective when pumping only at 1480 nm. In addition, a full comparison between the effect of temperature on some of the EDFA characteristics such as the maximum peak gain, optimum fiber length, saturation input power, and saturation output power has been carried out. The temperature variation in the range from −40 °C to +80 °C is taken into account.

Investigation of EDFA based 32 Channel C-Band Optical WDM System for Different Pumping Techniques

With the rise in demand for channel capacity, Wavelength Division Multiplexing (WDM) technique is employed in optical communication networks. Gain Flattened Erbium Doped Fiber Amplifier (EDFA) is used in optical WDM system to obtain a uniform output power level. The performance of EDFA depends on various parameters such as fiber length, pump power, pumping wavelength and pumping technique. The objective of this paper is to analyze the performance of EDFA for different pumping techniques namely co-propagating, counter-propagating and bidirectional propagating in a 32 channel C-band optical WDM transmission system at different levels of pump power and different fiber lengths. The system has been analyzed on the basis of received power, BER, gain, noise figure and Q- Factor in the wavelength range of 1528nm to 1562nm at 25dBm transmission power and 0.5nm channel spacing. The results obtained using different pumping techniques are compared to find an appropriate pumping technique which optimizes the performance of the optical WDM transmission system.

Site-Dependent Pumping Effect on Two-Level EDFAs

The impact of site-dependent pumping (SDP) on the performance of erbium-doped fiber amplifiers (EDFAs) pumped at wavelengths around 1480 nm is investigated, both experimentally and numerically. An improved numerical model incorporating the SDP effect for two-level EDFAs is derived and experimentally validated. We confirm by comparing with experimental data that the proposed model accurately describes the dependence of the amplifier gain spectrum on the pump wavelength and pump power. We conclude that SDP has a significant impact on the dynamic response of an EDFA due to input spectral variations and should be considered when simulating high performance links.

English

In the work, characteristics of the erbium-doped fiber amplifier (EDFA) are investigated. The amplification and noise figure dependences on different EDFA parameters in a 2.5 Gbit/s one-channel WDM transmission system are simulated and measured. Additionally, simulation of a four-channel 2.5 Gbit/s WDM system containing in-line amplifiers of the type was done in order to investigate the EDFA performance in multichannel systems. Almost identical results obtained for both the simulation model and the experimental system are indicative of high accuracy of the simulation. It is shown that the EDFA amplification depends on such parameters as the signal power, wavelength, EDF length, and configuration of the pump laser.   Key words: Wavelength division multiplexing (WDM), erbium-doped fiber amplifier (EDFA).

Arbitrary pulse shaping in Er-doped fiber amplifiers—Possibilities and limitations

Abstract A temporal deformation of nanosecond laser pulses occurring during an amplification process in a two-stage erbium-doped fiber amplifier operating in saturation is presented. We discuss distortion of rectangular laser pulses with duration ranging from 5 ns to 300 ns, generated at 20 kHz repetition rate. Calculations of a suitable peak power scaling factor for distorted pulses are presented. A simple compensation method of temporal pulse distortion, based on the direct current modulation with the use of arbitrary function generator (AFG), is also reported. An appropriate input pulse shape modification leads to obtaining an output amplified pulse with any desired shape. The main limitation of pulse shaping in a fiber amplifier seeded by a narrow linewidth laser diode turns out to be stimulated Brillouin scattering (SBS). However, the pulse shaping method can also improve the amplifier performance by increasing the power threshold of SBS. SBS phenomenon in the context of arbitrary pulse shaping have been also discussed.

Performance analysis of an optically amplified add/drop wavelength division multiplexing fiber communication link

The impact of power transients stemming from channel reconfiguration on erbium-doped fiber amplifier (EDFA) gain dynamics in wavelength division multiplexing (WDM) optical networks is investigated. The impact of power transients on EDFA gain dynamics leads to error bursts and impact on the network performance. First, we model an EDFA simulator with one-dimensional nonlinear differential equation that describes the time-dependent population density. For the model to show gain flattening multiplexed channels at different wavelengths, new function blocks are used. Next, to simulate the noise performance of EDFA, forward amplified spontaneous emission noise blocks are designed that add noise dynamically at signal wavelength. Finally, EDFA simulator is used as an in-line amplifier for amplitude shift keying-modulated WDM fiber communication link where the gain clamping facility is provided to protect power imbalance at the receiver. Next, we apply the mentioned model in the estimation on the link performance parameters, like signal-to-noise ratio and bit error rate, and variations in these values by channel add/drop results from variation in incremented signal output of EDFA. The variations are almost equal at different wavelengths in C- or L-band, which is due to flat gain and also the gain clamping facility of the present EDFA simulator.

Performance Optimization based Spectrum Analysis on OFRA and EDFA Devices

As the key devices, erbium doped fiber amplifier (EDFA) and optical Raman fiber amplifier (OFRA) have been widely applied in the fields of optical communication, sensing and measurement. However, the performance optimization is always one of the hot topics in the study of optical fiber amplifiers, because its output characteristics are hardly dependent to the key designing parameters. In this paper, in order to cope with such problem, we adopt the novel analysis based spectrum to study the output performance of EDFA and OFRA systems, respectively. Through simulating the operation of the two amplifying system, their output characteristics are first demonstrated with the various parameters. And according to the numerical results obtained, the key designing parameters of EDFA and OFRA systems are determinate, and the performance of amplifying systems are improved and optimized obviously in terms of output power, signal noise ratio, and the level of gain flatness. DOI: http://dx.doi.org/10.11591/telkomnika.v11i7.2822 Full Text: PDF

Performance analysis of dynamic erbium-doped fiber amplifier simulator

A real time multichannel dynamic erbium doped fiber amplifier (EDFA) Simulink model with flat gain and gain clamping facility has been developed on a MATLAB platform. We model the EDFA simulator with one-dimensional nonlinear differential equation that describes the time dependent population density. For the model to show gain flattening multiplexed channels at different wavelengths, the MATLAB function block is used. Next, to simulate the noise performance of EDFA. New forward amplified spontaneous emission (ASE) noise blocks are designed that add noise dynamically at signal wavelength. The model has been implemented in the study of performance characteristics of an EDFA in both C - and L -band signal amplification by simulation. Based on the designed ASE generator, noise figure for different signal wavelengths are calculated. For 980 nm pump power, the noise figure almost reaches the practical limit of 3 dB whereas for 1480 nm pump power, a variation of about 1.5 dB and 0.8 dB is observed from the practical limit for the C - and L -bands, respectively. The present model can be implemented successfully as a test bed in the study of EDFA gain dynamics over the entire third optical communication bandwidth (1525 to 1690 nm) in signal amplification.

Variable gain-flattened L-band erbium-doped fiber amplifier

This is a study on the design of variable gain-flattened erbium-doped fiber amplifier operating in L-band transmission window. Four amplifiers divided into five stages became the basis of the design with distributed pumping configuration. A dispersion compensating module was incorporated into the architecture as a way to combat dispersion. The amplifier was able to generate variable gain from 15 up to 30 dB under different input signal powers with a maximum output power of 23 dBm. Excellent gain flatness averaging around 0.8 dB was accomplished while four-wave mixing effect was significantly reduced.

A novel theoretical analysis of quadruple pass Erbium- doped fiber amplifier

A novel theoretical analysis model of dual stage quadruple pass (DSQP) Erbium-doped Fiber Amplifier (EDFA) is presented in this paper. This analysis is carried out by the broad input signal power starting from -50 to 0 dBm input signal with 10 to 220 mW pumping powers. The EDFA has been proposed and demonstrated by using an optical circulator and tunable band pass to reflect signal in each stage with a two level pump scheme through EDF length 10 and 15 m in the first and the second stage, respectively. The design parameters of EDFA are optimized using the numerical simulation of EDFA rate equations model in order to optimize the performance of EDFA. Finally, a comparative analysis is conducted to compare results of the theoretical modeling and the published experimental results. The comparative analysis showed that the proposed theoretical model has similar results compared to published experimental results.

Design of broadband erbium-doped fiber amplifier using very high-speed integrated circuit hardware description language for next-generation optical network

We mainly concentrate on the problem of gain broadening and flattening of erbium-doped fiber amplifier (EDFA) using dual forward-pumping configuration in which we use pumping both at 980 and 1480 nm wavelengths. The gain cascading of two EDFAs pumped separately at 980 and 1480 nm combines the advantage of high gain characteristics of 980 nm pumping and broad bandwidth characteristics of 1480 nm pumping. The use of increased number of channels in the present dense wavelength division multiplexing (DWDM) optical network requires a flat gain spectrum across the whole usable bandwidth. The use of very high-speed integrated circuit hardware description language (VHDL-AMS) in lightwave system modeling has been explored. Its application in designing wideband EDFA has not been reported thus far. This work facilitates to design broadband EDFA operating in both the C-band and L-band regions with VHDL-AMS. The amplifier design is made of a dual stage, copumped at 980 and 1480 nm, which delivers an average output power of -16 dBm over the entire 3-dB bandwidth of 80 nm.

A higher-order-mode Erbium-doped-fiber amplifier

We demonstrate the first erbium-doped fiber amplifier operating in a single, large-mode area, higher-order mode. A high-power, fundamental-mode, Raman fiber laser operating at 1480 nm was used as a pump source. Using a UV-written, long-period grating, both pump and 1564 nm signal were converted to the LP(0,10) mode, which had an effective area of 2700 microm(2) at 1550 nm. A maximum output power of 5.8 W at 1564 nm with more than 20 dB of gain in a 2.68 m long amplifier was obtained. The mode profile was undistorted at the highest output power.

The Effects of Complex Energy Transfer Dynamics and Gaussian Profiles on the Performance of High-Concentration EDFAs

In this paper, we investigate the effects of complex energy transfer dynamics and Gaussian profiles on the gain and noise figure performance of erbium-doped fiber amplifiers (EDFAs) with high doping concentration. We use a two-level system to study the complex energy transfer dynamics that comes from the homogeneous up-conversion (HUC) and the pair-induced quenching (PIQ). In our model, the system is stimulated by a pump source at the wavelength of 1480 nm and operated with a signal source at the wavelength of 1560 nm. Assuming a uniform distribution of erbium ions in the fiber core, we approximate the fundamental mode distributions by Gaussian profiles which are commonly used to calculate the mode radius or spot size. Using the numerical calculations and analysis of the rate and power propagation equations for a two-level model under consideration, the most advantageous Gaussian profile is determined as the Whitley mode radius to obtain a high-gain and a low-noise figure per unit length of silica-based fiber amplifiers. The effects of the number of ions per cluster and the percentage of ions in clusters on the calculated gain and noise figure are compared for several pump powers. Results are discussed to achieve a desired gain and noise figure performance, and compared with the available experimental data to verify the feasibility of the model.

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.

Transient Performance of Erbium-doped Fiber Amplifiers using a New Feedforward Control taking into account Wavelength Dependence

Article Transient Performance of Erbium-doped Fiber Amplifiers using a New Feedforward Control taking into account Wavelength Dependence was published on June 1, 2007 in the journal Journal of Optical Communications (volume 28, issue 2).

Uncooled Mini-DIL Module for 980-nm Pump Lasers

The importance of lower cost while maintaining high performance of erbium-doped fiber amplifiers (EDFAs) is growing with increased bandwidth demand. The uncooled 980-nm miniature dual-inline (Mini-DIL) pump laser is attractive for compact EDFA designs because it offers the advantages of lower cost, smaller footprint, minimal heat generation, and reduced electrical power consumption. In this paper, we report a low-cost uncooled Mini-DIL module designed for 980-nm pump lasers. A three-dimensional finite element analysis model effectively predicts module thermal and stress performance. Experimental results of module power and coupling efficiency stability over assembly processes are presented. A minimum optical output power of 150 mW is achieved in a group of 10 devices across a temperature range of 0/spl deg/C to 70/spl deg/C at a drive current of 350 mA with a 1.5-mm raised ridge InGaAs/AlGaAs single quantum well laser chip.