Gallium-doped InP/ZnSeS/ZnS quantum dots as a saturable absorber for passive Q-switched fiber laser

In this work, Gallium-doped InP/ZnSeS/ZnS (InP-Ga) QDs was fabricated by thermal injection method for the first time. The Q-switching operations were carried out by integrating InP–Ga QDs as saturable absorber (SA) in a fiber laser ring cavity system. Q-switched laser pulses with a pulse width of 89.8 ns were generated. The ability of effective pulse width compression can be attributed to the short exciton recovery time of SA, as confirmed by transient absorption and time-resolved photoluminescence. This is the first demonstration of Ga-doped InP/ZnSeS/ZnS QDs and using it as SA for generating ultrafast laser pulses. Therefore, this study extends the research scope of InP-based QDs in optical communications, nonlinear photonics and ultrafast photonics.