Passively mode-locked dual-wavelength Er-doped fiber laser based on antimony tin oxide as saturable absorber

As a typical transparent conductive oxide, antimony tin oxide (ATO) is widely applied in many optical fields. However, investigations of the nonlinear absorption properties of ATO have not been reported so far. In this study, ATO was employed as a saturable absorber (SA) for producing an Er-doped pulsed fiber laser. To our knowledge, this is the first time that ATO has been used to fabricate an SA. Its appearance and nonlinear saturable absorption characteristics were investigated in our experiment. The saturation intensity and modulation depth of the ATO-SA were 7.51 MW cm⁻² and 2.30%, respectively. By adjusting the polarization controllers and the pump power, dual-wavelength pulses were generated within an Er-doped fiber laser. The dual-wavelength pulses were centered at wavelengths of 1558.3 nm and 1558.7 nm with a repetition rate of 1.04 MHz. The pulse width was 4.42 ns. Our results fully prove that ATO with its excellent nonlinear absorption properties will have wide potential ultrafast photonic applications. (paper)