Method for adjusting the gain slope of a two-stage erbium-doped fiber amplifier with suppression of gain shape variation

Iudin V.А., Pogudin G.К., Nazarenko V.N., Alyabiev K.А., Aleynik, А.S.

For Russian citation (Opticheskii Zhurnal):

Иудин В.А., Погудин Г.К., Назаренко В.Н., Алябьев К.А., Алейник А.С. Метод настройки крутизны спектральной характеристики усиления двухкаскадного эрбиевого усилителя при сохранении формы спектральной характеристики усиления // Оптический журнал. 2026. Т. 93. № 11. С. 5–17. http://doi.org/10.17586/1023-5086-2026-93-11-05-17

Iudin V.A., Pogudin G.K., Nazarenko V.N., Alyabyev K.A., Aleynik A.S. Method for adjusting the gain slope of a two-stage erbium-doped fiber amplifier with suppression of gain shape variation [in Russian] // Opticheskii Zhurnal. 2026. V. 93. № 11. P. 5–17. http://doi.org/10.17586/1023-5086-2026-93-11-05-17

For citation (Journal of Optical Technology):

Abstract:

Subject of study. Spectral characteristics of the gain of a two-stage erbium-doped fiber amplifier. Aim of study. To develop a method for adjusting the gain slope of a two-stage erbium-doped fiber amplifier while minimizing changes in the gain shape. Method. A mathematical model was developed and used for numerical simulation of the amplifier’s spectral characteristics. The changes in these characteristics caused by variations in the erbium-doped fiber length and simultaneous control of the input signal power and pump power were experimentally investigated. The experimental data were compared with the simulation results. Main results. A new model for calculating the gain slope and gain shape was proposed, and the amplifier parameters that allow the gain slope to be varied while preserving the gain shape were determined. A method for adjusting the gain slope was developed and experimentally tested. A slope tuning range from –0.06 to 0.04 dB/nm was achieved, with a change in the gain shape of no more than 0.4 dB. The difference between the calculated and experimental gain slopes did not exceed 0.02 dB/nm, while the difference in the shape coefficient was 0.4 dB. Practical significance. The achieved gain-slope tuning range exceeds the attenuation slope of a 100-km fiber, which ranges from –0.04 to –0.02 dB/nm in long-haul communication lines. Implementation of the proposed method will make it possible to eliminate slope equalizers in submarine fiber-optic communication systems, thereby reducing the complexity, optical losses, and cost of such systems.

Keywords:

erbium-doped fiber amplifier, spectral gain characteristic, gain slope, gain shape, dense wavelength division multiplexing, McCumber reciprocity theory, population inversion, gain flattening filter

Acknowledgements:

this work was supported by the Russian Science Foundation grant № 25-12-20017, and by the Saint Petersburg Science Foundation grant.

OCIS codes: 060.2320, 060.2410, 060.2330

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