Single-longitudinal mode quadruple wavelength C plus L-band erbium-doped fiber laser based on the pairs of reflective fiber bragg gratings

Flatness of lasing wavelengths of a multi-wavelength fiber laser (MWFL) is an important design constraint that is considered attractive in various applications of photonics and optical communication systems. In this work, we propose a single-longitudinal mode (SLM) quadruple wavelength C+L-band Erbium-doped fiber laser (EDFL) with high output power flatness. It is implemented with a short piece of Erbium-doped fiber (EDF) pumped by conventional 980 nm laser diode and four pairs of reflective fiber Bragg gratings (FBGs) through numerical simulations. The reflectivities of FBGs are adjusted such that SLM quadruple wavelengths are obtained at the output of EDFL with flatness of 0.9 dB, optical signal-to-noise ratio (OSNR) in the range of 44.5-53.2 dB, and linewidths (LWs) in the range of 5.4-7.3 MHz. Slope efficiency (SE) of around 24% is achieved considering the total power of all lasing wavelengths generated. Moreover, the power variation around 0.1 dB for lasing wavelengths of 1540.2 nm and 1605.7 nm is noticed for twelve iterations each repeating after five-minute interval. The proposed SLM quadruple wavelength EDFL has promising application prospects for distributed sensing and optical communication systems due to excellent performance metrics.