Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of the Optical Society of America B

Gain and noise in rare-earth-doped optical fibers

Marco Montecchi, Antonio Mecozzi, M. Settembre, Mario Tamburrini, L. Di Gaspare

Published Jan 1, 1991• 10 citations
Publisher

Abstract

Two pumping schemes are considered for optical amplifiers based on rare-earth-doped optical fibers in which pump light is fed either along with the signal light (copropagating) or through the opposite end of the fiber (counterpropagating), including the effects of the excited-state absorption (ESA) process. A rate-equation analysis shows that when ESA is absent the signal gain is the same in both pumping schemes, even under gain saturation, whereas when ESA is present the saturated signal gain is larger in the counterpropagating scheme. Independently of ESA the optical signal-to-noise ratio at the amplifier output is the same in both pumping schemes if the dopant behaves as a four-level laser system, and it is larger in the copropagating scheme for a three-level dopant.

DOI
10.1364/josab.8.000134

Related papers

Closed-form expressions for the gain in three- and four-level laser fibers

Michel J. F. Digonnet

Exact and approximate theoretical models of the small-signal single-pass gain in single-mode three-level laser fibers are presented. These models are relevant to the behavior of rare-earth-doped (in particular Er/sup 3+/) silica-based fibers. They account for the effects of both the pump and signal-mode structures and pump excited-state absorption (ESA), the latter being present for some pump wavelengths in Er-doped silica fibers. By relying on the modal overlap integral formalism for four-level lasers, relatively simple closed-form expressions for the pump absorption and the gain are derived. These expressions are also applicable to four level laser fibers by a simple adjustment of some of the model parameters.>

IEEE Journal of Quantum Electronics•Jan 1, 1990•79 citations

Signal amplification in strongly pumped fiber amplifiers

Amos A. Hardy, Ram Oron

Signal amplification is analyzed in strongly pumped fiber amplifiers both for three-level and four-level transitions, including scattering loss and excited state absorption. Simple analytic expressions are derived for the signal amplification and pump attenuation, along the fiber length, when either the signal and the pump are injected at the same fiber end (forward pumping) or when they are injected at the two opposite ends (backward pumping). Numerical examples for rare-earth doped fibers show excellent agreement between the analytical solution and the exact numerical solutions of the rate-equations for practical operating conditions.

IEEE Journal of Quantum Electronics•Mar 1, 1997•124 citations

Optimization of the power ratios of the bidirectional pumping at two wavelengths for erbium-doped fiber amplifiers

Yu. A. Varaksa, George V. Sinitsyn, Mikhail A. Khodasevich

The gain and noise factor spectra of erbium-doped fiber amplifiers with pumped according to a copropagating three-level scheme and according to a counterpropagating quasi-two-level scheme in the regime of unsaturated gain in the C band have been simulated numerically. It has been shown that, at the total pump power up to 30 mW and at the optimized power ratio of the copropagating and counterpropagating pumps, the inhomogeneity of the gain in the C band does not exceed 0.25 dB at the noise factor of 4.2–4.7 dB.

Optics and Spectroscopy•Apr 1, 2007•4 citations

Brillouin-like effects in rare-earth-doped bi-directional optical fiber amplifiers

Andrei A. Fotiadi, Dmitry A. Korobko, Ivan Chapalo +2 more

Brillouin amplification, the most prominent effect implemented with Brillouin dynamical gratings (BDG), enables exponential narrowband gain that is Stokes-shifted by some value in the GHz range. In this process, the interaction of the counterpropagating pump and Stokes waves through a BDG they produce causes an increase of the Stokes-shifted wave amplitude and decrease of the pump wave amplitude during their propagation through the fiber. Here, we report on a similar effect that could be implemented in rare-earth-doped fibers with the population inversion dynamical gratings. The effect is the most pronounced in a bidirectional rare-earth-doped optical fiber amplifier. Two monochromatic optical signal waves are introduced into the fiber from opposite ends and experience amplification (if the fiber is pumped) or attenuation (if the fiber is unpumped) as they propagate through the fiber. The signal waves are coherent on a sub-kHz level and slightly detuned. In terms commonly accepted in stimulated Brillouin scattering these counterpropagating signal waves correspond to what is referred to as "pump" and "Stokes" waves. However, in contrast to the Brillouin process, their interference inside the rare-earth-doped fiber creates not acoustic, but the population inversion dynamical gain grating. Then interaction between the signal waves and created population inversion dynamical gratings cause a strong power transfer from one signal wave to another.

•Jun 5, 2023•0 citations

Excited-State Absorption at 1.5 µm in Er3+-Doped Fiber Amplifiers

Peter Blixt, Johan Nilsson, Jurgis Gintautas Babonas +1 more

Erbium-Doped Fiber Amplifiers (EDFAs) can very efficiently convert pump to signal energy. Quantum efficiencies higher than 80 % with 1.48 pm pump [1], and 93% when pumped at 980 nm [2] are reported. However, even higher values should be theoretically possible for an ideal EDFA. Various physical effects may lead to quantum efficiency (QE) reduction. Not all of them are quite well understood yet. At Erbium concentrations above 100 ppm by weight the pump loss is partly explained by energy transfer between two excited ions resulting in upcon- version process [3]. At low concentrations Excited-State Absorption (ESA) could be a more significant effect reducing QE. ESA of photons from 1.5 |im band have been predicted from absorption measurements [4] and also observed [5]. However, to our knowledge, no quantitative analysis has been made which would distinguish between the contributions of ESA and two-particle upconversion when measurements of short wavelength luminescence were performed.

Optical Amplifiers and Their Applications•Jan 1, 1992•2 citations

Unified model for analysis of light amplification in rare-earth doped fibers

J. Bai, E. Towe

This paper discusses a unified method for modeling and simulating signal light amplification in rare-earth doped optical fiber amplifiers. The model accounts for gain saturation, spontaneous emission, dispersion, and nonlinear effects along the length of the distributed gain medium. Simulations based on the unified model are shown to compare favorably with experimental results. The new model can be used to provide guidance in the design and construction of a variety of fiber-based optical amplifiers. Furthermore, it is suitable for analyzing the performance of high-power amplifiers in a wide range of operating conditions.

Journal of the Optical Society of America B•Oct 20, 2014•4 citations
Two pumping schemes are considered for optical amplifiers based on rare-earth-doped optical fibers in which pump light is fed either along with the signal light (copropagating) or through the opposite end of the fiber (counterpropagating), including the effects of the excited-state absorption (ESA) process. A rate-equation analysis shows that when ESA is absent the signal gain is the same in both pumping schemes, even under gain saturation, whereas when ESA is present the saturated signal gain is larger in the counterpropagating scheme. Independently of ESA the optical signal-to-noise ratio at the amplifier output is the same in both pumping schemes if the dopant behaves as a four-level laser system, and it is larger in the copropagating scheme for a three-level dopant.
Exact and approximate theoretical models of the small-signal single-pass gain in single-mode three-level laser fibers are presented. These models are relevant to the behavior of rare-earth-doped (in particular Er/sup 3+/) silica-based fibers. They account for the effects of both the pump and signal-mode structures and pump excited-state absorption (ESA), the latter being present for some pump wavelengths in Er-doped silica fibers. By relying on the modal overlap integral formalism for four-level lasers, relatively simple closed-form expressions for the pump absorption and the gain are derived. These expressions are also applicable to four level laser fibers by a simple adjustment of some of the model parameters.>
Signal amplification is analyzed in strongly pumped fiber amplifiers both for three-level and four-level transitions, including scattering loss and excited state absorption. Simple analytic expressions are derived for the signal amplification and pump attenuation, along the fiber length, when either the signal and the pump are injected at the same fiber end (forward pumping) or when they are injected at the two opposite ends (backward pumping). Numerical examples for rare-earth doped fibers show excellent agreement between the analytical solution and the exact numerical solutions of the rate-equations for practical operating conditions.
The gain and noise factor spectra of erbium-doped fiber amplifiers with pumped according to a copropagating three-level scheme and according to a counterpropagating quasi-two-level scheme in the regime of unsaturated gain in the C band have been simulated numerically. It has been shown that, at the total pump power up to 30 mW and at the optimized power ratio of the copropagating and counterpropagating pumps, the inhomogeneity of the gain in the C band does not exceed 0.25 dB at the noise factor of 4.2–4.7 dB.
Brillouin amplification, the most prominent effect implemented with Brillouin dynamical gratings (BDG), enables exponential narrowband gain that is Stokes-shifted by some value in the GHz range. In this process, the interaction of the counterpropagating pump and Stokes waves through a BDG they produce causes an increase of the Stokes-shifted wave amplitude and decrease of the pump wave amplitude during their propagation through the fiber. Here, we report on a similar effect that could be implemented in rare-earth-doped fibers with the population inversion dynamical gratings. The effect is the most pronounced in a bidirectional rare-earth-doped optical fiber amplifier. Two monochromatic optical signal waves are introduced into the fiber from opposite ends and experience amplification (if the fiber is pumped) or attenuation (if the fiber is unpumped) as they propagate through the fiber. The signal waves are coherent on a sub-kHz level and slightly detuned. In terms commonly accepted in stimulated Brillouin scattering these counterpropagating signal waves correspond to what is referred to as "pump" and "Stokes" waves. However, in contrast to the Brillouin process, their interference inside the rare-earth-doped fiber creates not acoustic, but the population inversion dynamical gain grating. Then interaction between the signal waves and created population inversion dynamical gratings cause a strong power transfer from one signal wave to another.
Erbium-Doped Fiber Amplifiers (EDFAs) can very efficiently convert pump to signal energy. Quantum efficiencies higher than 80 % with 1.48 pm pump [1], and 93% when pumped at 980 nm [2] are reported. However, even higher values should be theoretically possible for an ideal EDFA. Various physical effects may lead to quantum efficiency (QE) reduction. Not all of them are quite well understood yet. At Erbium concentrations above 100 ppm by weight the pump loss is partly explained by energy transfer between two excited ions resulting in upcon- version process [3]. At low concentrations Excited-State Absorption (ESA) could be a more significant effect reducing QE. ESA of photons from 1.5 |im band have been predicted from absorption measurements [4] and also observed [5]. However, to our knowledge, no quantitative analysis has been made which would distinguish between the contributions of ESA and two-particle upconversion when measurements of short wavelength luminescence were performed.
This paper discusses a unified method for modeling and simulating signal light amplification in rare-earth doped optical fiber amplifiers. The model accounts for gain saturation, spontaneous emission, dispersion, and nonlinear effects along the length of the distributed gain medium. Simulations based on the unified model are shown to compare favorably with experimental results. The new model can be used to provide guidance in the design and construction of a variety of fiber-based optical amplifiers. Furthermore, it is suitable for analyzing the performance of high-power amplifiers in a wide range of operating conditions.