Wavelength-switchable L-band fiber laser assisted by random reflectors

A wavelength-switchable L-band erbium-doped fiber laser (EDFL) assisted by an artificially controlled backscattering (ACB) fiber reflector is here presented. This random reflector was inscribed by femtosecond (fs) laser direct writing on the axial axis of a multimode fiber with 50 um core and 125 um cladding with a length of 17 mm. This microstructure was placed inside a surgical syringe to be positioned in the center of a high-precision rotation mount to accurately control its angle of rotation. Only by rotating this mount, three different output spectra were obtained: a single wavelength lasing centered at 1574.75 nm, a dual wavelength lasing centered at 1574.75 nm and 1575.75 nm, and a single wavelength lasing centered at 1575.5 nm. All of them showed an optical signal-to-noise ratio (OSNR) of around 60 dB when pumped at 300 mW. This work was financed by the program “José Castillejo para estancias de movilidad en el extranjero de jóvenes doctores”, funded by the Ministerio de Universidades of Spain (reference CAS21/00351); the Spanish AEI projects PID2019-107270RB, funded by MCIN/AEI/10.13039/501100011033 and FEDER “A way to make Europe”, and projects PDC2021-121172 and TED2021-130378B funded by MCIN/ AEI/10.13039/501100011033 and European Union “Next generation EU”/PTR. Finally, the work was also founded by the Ministerio de Educación, Cultura y Deporte of Spain (PhD grant FPU2018/02797).