Gain-flattened Erbium-doped Fiber Amplifier Research Articles

Intrinsically gain-flattened Erbium-doped fiber amplifier for metro networks

Intrinsically gain-flattened Erbium-doped fiber amplifier for metro networks

Temperature-insensitive, gain flattened erbium-doped photonic crystal fiber amplifier: a compatible solution

An all-silica, erbium-doped photonic crystal fiber (PCF) has been investigated numerically to achieve temperature insensitive amplification for optical communication applications. The careful engineering of PCF microstructured air-hole cladding offers two distinct advantages over conventional fibers, namely, compatible mode area and large modal overlap which can be controlled accurately to lower the splice loss and shorten the fiber length respectively. Splice loss as low as 0.22 dB and fiber length as short as 3.25 m for 190 mW pump power and 1 µW signal power, have been achieved in this work. Apart from these two existing advantages, a third advantage has been highlighted and numerically verified in this paper. This third advantage concerns the realization of an athermal long period grating (LPG) filter to flatten the amplifier’s gain spectrum. The LPG which exhibits a gain ripple of 0.29 dB over a 25 nm wavelength band at room temperature (20 °C), does not respond significantly with temperature and sub-dB ripples within 0.64 dB are maintained when temperature changes over a 80 °C range (−20 to +60 °C). This athermal nature of the flattened gain spectrum is attributed to the single material composition of the PCF, which is clearly unachievable with conventional fibers.

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.

Optimizing the EDFA gain for WDM lightwave system with temperature dependency

The gain-flattened erbium-doped fiber amplifier (EDFA) is a key device for wavelength division multiplexing (WDM) modern optical network systems. A flat spectral gain EDFA has been achieved by controlling the doped fiber length and the pump power. The purpose of this paper is to study the variation of gain flattening over the temperature range from −20 to +60°C. The results obtained here indicate that gain flatness increases as temperature increases.

增益平坦掺铒光纤放大器中均匀信号强度造成的光谱烧孔效应

Spectral hole burning (SHB) effects in a gain-flattened erbium-doped fiber amplifier (EDFA) are demonstrated to be significant in the presence of large signal power around the 1530?1532-nm wavelength range. These are the first effects reported in a setup employing equivalent power level distribution of 40 channels ranging from 1530 to 1561 nm. To explain this, the introduction of a new local population variable into the laser equation is required to support the original inversion ratio that is determined by the pump lasers. In the analysis section, spectroscopic parameters and high signal powers are considered to be other contributing parameters to the change in the gain characteristics. An improvement to this theoretical basis is suggested by implementing mathematical modeling to validate similarities between the gain shape of simulation to that obtained in the experiment.

Spectral gain characteristics induced by 980 nm pumping band in a gain-flattened EDFA

We demonstrate the effect of inversion population ratio mediated by 980 nm pumping band on the gain spectra of a gain-flattened Erbium-doped fiber amplifier. The gain equalizing filter was designed at 977 nm and the amplifier was built in the four-stage arrangement. In the pumping structure, the 1480 nm lasers were maintained in the final gain block while the 980 nm band lasers were utilized in the first three blocks. These laser sources were arranged at several combinations of 977 and 980 nm wavelengths. Within these 3 nm spectrum, an absorption cross-section difference around 0.32 × 10−25 m2 contributed to a dispensable gain variation up to 3-dB. These inequalities were the results of variations in population inversion induced by the pump wavelength discrepancy. The findings show the importance of designing a filter at the specific absorption wavelength to allow the operation of consistent gain level.

Gain-flattened erbium-doped fiber amplifier with flexible selective band for optical networks

Erbium-doped fiber amplifier with flat gain over 30 nm bandwidth is demonstrated using flexible selective band methods. The band optical amplifier was designed to cater 44 wavelength division multiplexing channels which were separated into bands of 4 nm. Without using any gain flattening filter, the gain of optical amplifier was maintained at 19 dB with a maximum gain variation of less than 1.6 dB even though the input signal power was varied from -19 to -6 dBm. The amplifier was able to maintain 1 dB gain flatness with 83% chance for any selective bands of 4 nm within the wavelength range from 1530 to 1565 nm. This feature is very attractive to support band optical networks.

Optimization of gain flattened C-band EDFA using macro-bending

Optimization of gain flattened C-band erbium-doped fiber amplifier (EDFA) using a macrobending method with an improved gain flatness and bandwidth is demonstrated. The optimization for gain flatness and bandwidth was achieved by varying the bending radius and the length of the doped fiber. In the optimized condition, the gain saturation effect as well as the energy transfer from shorter wavelengths to longer wavelengths resulted in a flattened and broadened gain profile in the C-band region. The amplifier was optimized to a 9 m long erbium-doped fiber (EDF) with erbium ion concentration of 1100 ppm and bending radius of 6.5 mm. The gain variation of the EDFA is obtained within ±1 dB over 25 nm bandwidth of C-band region.

Simplified ASE correction algorithm for variable gain-flattened erbium-doped fiber amplifier

We demonstrate a simplified algorithm to manifest the contribution of amplified spontaneous emission in variable gain-flattened Erbium-doped fiber amplifier (EDFA). The detected signal power at the input and output ports of EDFA comprises of both signal and noise. The generated amplified spontaneous emission from EDFA cannot be differentiated by photodetector which leads to underestimation of the targeted gain value. This gain penalty must be taken into consideration in order to obtain the accurate gain level. By taking the average gain penalty within the dynamic gain range, the targeted output power is set higher than the desired level. Thus, the errors are significantly reduced to less than 0.15 dB from 15 dB to 30 dB desired gain values.

Gain optimization of an erbium-doped fiber amplifier and two-stage gain-flattened EDFA with 45 nm flat bandwidth in the L-band

An erbium-doped fiber amplifier (EDFA) is simulated. The variation of gain with different parameters is obtained and the values of these parameters are optimized to achieve a maximum value of gain. A two-stage gain-flattened EDFA consisting of two EDFAs in series is also simulated. In the operating range of 1565–1610 nm, the flat gain of 46 dB is obtained.

금속선의 주기적 배열로 유도된 장주기 격자를 이용한 이득 평탄화된 광섬유 증폭기 제작

In this study, we have fabricated a gain flattened erbium-doped optical fiber amplifier. Gain flattening filters were realized by the strain-induced long period fiber gratings, which are made of periodically arrayed metal wires. Using the filter of period, spontaneous emission amplified at C-band wavelength by a 980nm pumping laser was flattened within 1dB of gain ripple. The performance of the simultaneous multi channel amplification was measured using a fabry-perot laser diode. Amplification ratio was above 20dB. This amplifier can be applied to the long distance transmission system based on a wavelength division multiplexing for boosting an attenuated signal.

Segmented-clad fiber design for tunable leakage loss

This paper proposes a novel segmented-clad fiber (SCF) design in which the spectral variation of leakage loss of the fundamental mode can be finely tuned by varying the fiber parameters. A fiber with such optimized spectral variation of leakage loss should find application in the realization of inherently gain-flattened optical fiber amplifiers, wavelength filters, wavelength-flattened attenuators, etc. In this paper, the authors present SCF designs optimized for realizing inherently gain-flattened S-band erbium-doped fiber amplifier (EDFA) and high-gain discrete Raman fiber amplifier (RFA). Amplifier characteristics have been modeled in both cases, and simulations show that a 20-dB gain with /spl plusmn/0.9 dB of gain ripple over a 30-nm bandwidth in S-band is achievable with the designed EDFA based on the optimized SCF. In case of discrete RFA based on SCF, a 20-dB net gain with /spl plusmn/0.5-dB ripple is shown to be achievable over a 28-nm wavelength range in S-band.

Use of a genetic algorithm to optimize multistage erbium-doped fiber-amplifier systems with complex structures

We propose optimizing multifunctional multistage erbiumdoped fiber amplifiers (EDFAs) with complex structures by use of a genetic algorithm. With this method, we investigated optimum configurations of C- and L-band gain-flattened multistage EDFAs containing gain-flattening filters and high-loss interstage elements for dense wavelength-division multiplexing systems in detail and compared the amplifiers with various kinds of configurations under different design criteria. With the guidance of optimization results, the roles of all the factors such as pumping schemes, pump-power allocation, component position, and insertion loss in the optimization of EDFAs have been studied, and useful guidelines for optimizations have been provided.

A dynamically gain‐flattened erbium‐doped fiber amplifier

AbstractThis paper reports on dynamically gain‐flattened C‐ and L‐band erbium‐doped fiber amplifiers (DGF‐EDFAs), whose dynamic gain ranges are above 20 dB and 24 dB, respectively. This paper gives the detailed test and comparative results for DGF‐EDFAs based on the use of a voltage‐controlled fiber‐based gain tilt controller and a variable optical attenuator. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 8–11, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11110

A gain-flattened L-band dual-core erbium-doped fibre amplifier

An L-band erbium-doped fibre amplifier consisting of a length of dual-core fibre is reported. It has a flat gain from 1565 to 1615 nm with a maximum gain variation of 0.6 dB, and noise figure less than 3.9 dB.

S-band erbium-doped silica fibre amplifier with flattened-gain of over 21 dB

A gain-flattened erbium-doped silica fibre amplifier (EDSFA) has been developed for amplifying WDM signals in the S-band. The EDSFA exhibits a signal gain of over 21 dB, a gain excursion of less than 1.9 dB, and a noise figure of less than 6.7 dB in the 1491–1518 nm wavelength range.

1.58-μm broad-band erbium-doped tellurite fiber amplifier

This paper describes the development of a 1.58-/spl mu/m broad-band and gain-flattened erbium-doped tellurite fiber amplifier (EDTFA). First, we compare the spectroscopic properties of various glasses including the stimulated emission cross sections of the Er/sup 3+4/ I/sub 13/2/ /sup 4/I/sub 15/2/ transition and the signal excited-state absorption (ESA) cross sections of the Er/sup 3+4/ I/sub 13/2/ - /sup 4/I/sub 9/2/ transition. We detail the amplification characteristics of a 1.58-/spl mu/m-band EDTFA designed for wavelength-division-multiplexing applications by comparing it with a 1.58-/spl mu/m-band erbium-doped silica fiber amplifier. Furthermore, we describe the 1.58-/spl mu/m-band gain-flattened EDTFA we developed using a fiber-Bragg-grating-type gain equalizer. We achieved a gain of 25.3 dB and a noise figure of less than 6 dB with a slight gain excursion of 0.6 dB over a wide wavelength range of 1561-1611 nm. The total output power of the EDTFA module was 20.4 dBm and its power conversion efficiency reached 32.8%.

Reconfigurable Gain-flattened Erbium-doped Fiber Amplifiers with Variable Gain at Improved Noise Characteristics

Article Reconfigurable Gain-flattened Erbium-doped Fiber Amplifiers with Variable Gain at Improved Noise Characteristics was published on August 1, 2002 in the journal Journal of Optical Communications (volume 23, issue 4).

Optimum configuration and design of 1480-nm pumped L-band gain-flattened EDFA using conventional erbium-doped fiber

We theoretically investigate optimum configurations of 1480-pumped L-band (1570–1610 nm) gain-flattened erbium-doped fiber amplifier (EDFA), using conventional erbium-doped fiber, for multi-wavelength wavelength division multiplexing (WDM) systems. The design criterion of L-band EDFA is to achieve the highest channel output power while keeping the differential channel output power to be ≤0.7 dB among 32 digital baseband channels with low channel noise figure of ≤5.5 dB. A total of nine L-band EDFA configurations are examined and compared. These configurations considered include the dual-forward, dual-backward, and different bi-directional pumping schemes, each with and without the midway optical isolator. Among all configurations, we find that the pump-passed case in forward-and-backward pumping scheme is the best amplifier configuration to offer the highest channel output power with good channel gain uniformity and moderate low noise figure. In addition, the tolerance of the ratio of first-staged EDF length to the total EDF length, and the effects of optical isolation of midway isolator, and pump power degradation on the characteristics of the best configuration are also examined. This investigation provides the EDFA configuration selection for multi-wavelength WDM L-band lightwave systems.

Gain-flattened fiber amplifier from 1560 to 1580 nm wavelengths using an erbium-doped fiber amplifier

A simple gain-flattened L-band erbium-doped fiber amplifier (EDFA) is demonstrated. An L-band flat gain range of 20 nm (1560–1580 nm) is achieved for use in wavelength-division multiplexing (WDM) transmission systems. Gain flatness with a 1 dB gain discrepancy is obtained through manipulation of the pump power, and no additional devices (gain equalizer, attenuator, fiber-Bragg grating) are required. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 221–223, 2000.