Performance enhancement of two-stage erbium-ytterbium co-doped fiber amplifiers using wavelength-selective reflective feedback loop

The objective of this work is to present a new design that will improve the gain and reduce the noise figure (NF) of a two-stage erbium-ytterbium-doped fiber amplifier (EYDFA) operating at the end of the C-band and L-band. The design of the new EYDFA will be optimized numerically using a wavelength-selective reflective feedback loop with two fiber Bragg gratings (FBGs) at 1530 and 1560 nm, while recycling the amplified spontaneous emission (ASE) signals traveling in the backward direction to the amplifier’s active medium. A physical model has been created to simulate and analyze how FBGs provide feedback that influences ion population dynamics and energy transfer between ions. The amplifier performance has been systematically characterized through a series of numerical simulations of single- and dual-FBG systems with a pump at 1025 nm and an input signal power of – 25 dBm over the wavelength range 1545–1605 nm. The numerical results indicate that the dual-FBG configuration of the EYDFA demonstrates improved performance characteristics compared to a conventional EYDFA configuration. With the proposed EYDFA design, an optical gain of 44.57 dB, an OSNR of 43.89 dB, an NF value of 3.3 dB, and an ASE output of − 3.54 dBm have been achieved. These optical performance indicators can be considered an efficient and effective means of supporting the development of future optical communication networks.