Nonlinear optical absorption properties of zirconium selenide in generating dark soliton and dark-bright soliton pairs

Abstract

Our work reports the preparation of zirconium selenide (<i>Z</i><i>r</i><i>S</i><i>e</i>₂)-polyvinyl alcohol (PVA) film-type saturable absorber (SA) and its nonlinear absorption performance in obtaining dark soliton and dark-bright soliton pairs in an Er-doped fiber (EDF) laser for the first time, to the best of our knowledge. The saturation intensity and modulation depth of the <i>Z</i><i>r</i><i>S</i><i>e</i>₂-<i>P</i><i>V</i><i>A</i> SA were ∼12.72<i>M</i><i>W</i>/<i>c</i><i>m</i>² and 2.3%, respectively. Due to the modulation of the SA, under a pump power of 525.2 mW, stable dark soliton operation with an average output power of 9.75 mW, and a pulse repetition frequency of 20.84 MHz, a pulse width of 3.85 ns was attained successfully. By adjusting the state of the polarization controllers, dark-bright soliton pairs were also observed. To the best of our knowledge, this was the first demonstration focusing on the nonlinear optical absorption applications of <i>Z</i><i>r</i><i>S</i><i>e</i>₂ in obtaining dark soliton and dark-bright soliton pairs. Our results show that <i>Z</i><i>r</i><i>S</i><i>e</i>₂ is a good two-dimensional SA material for acting as an ultrafast optical device due to its suitable nonlinear optical absorption properties.