Zinc selenide saturable absorber for ultrashort pulse fiber laser generation in C–band region

A mode-locked ultrashort pulse fiber laser by incorporating zinc selenide (ZnSe) as a saturable absorber (SA) is proposed and demonstrated in this work. ZnSe nanoparticles can be incorporated in the ring laser cavity together with an erbium doped fiber as a gain medium in generating a mode-locked output with a repetition rate of 11.69 MHz; a peak-to-pedestal extinction ratio of 53.32 dB and a pulse duration of 867 fs. A stable mode-locked output spectrum was generated at central wavelength of 1550 nm with a 3 dB bandwidth of 4.91 nm and a maximum average output power of 16.09 mW. The synthesis of ZnSe nanoparticles were carried out by using the microwave-assisted hydrothermal method. The structural and optical properties of these nanoparticles have been examined by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), UV–Vis diffuse reflectance and photoluminescence spectroscopies. The ZnSe nanoparticles was found to exhibit cubic structure with an average particle size of 35.99 ± 0.93 nm, which is in close agreement with the result obtained from the FESEM image. The results revealed that the measured particle size diameter was further confirmed by using Rietveld refinement method from XRD data. UV–Vis diffuse reflectance and photoluminescence spectroscopies measurements showed that the optical band gap of ZnSe nanoparticles are 2.64 ± 0.02 eV. To date, this is the first demonstration of mode-locked fiber laser generation utilizing ZnSe nanoparticles as a saturable absorber.