Synthesis of WS(1.76)Te(0.24) alloy through chemical vapor transport and its high-performance saturable absorption

Layered transitional metal dichalcogenides (TMDs) are drawing significant attentions for the applications of optics and optoelectronics. To achieve optimal performances of functional devices, precisely controlled doping engineering of 2D TMDs alloys has provided a reasonable approach to tailor their physical and chemical properties. By the chemical vapor transport (CVT) method and liquid phase exfoliation technique, in this work, we synthesized WS(1.76)Te(0.24) saturable absorber (SA) which exhibited high-performance of nonlinear optics. The nonlinear saturable absorption of the WS(1.76)Te(0.24) SA was also measured by the open aperture Z-scan technique. Compared to that of the binary component WS(2) and WTe(2), WS(1.76)Te(0.24) SA has shown 4 times deeper modulation depth, 28% lower saturable intensity and a much faster recovery time of 3.8 ps. The passively Q-switched laser based on WS(1.76)Te(0.24) was more efficient, with pulse duration narrowed to 18%, threshold decreased to 28% and output power enlarged by 200%. The promising findings can provide a method to optimize performances of functional devices by doping engineering.