Nonlinear absorption of the films containing Ag ₂ S, Ag ₂ Se, PbS, and PbSe quantum dots using 1030 nm and 515 nm pulses

The saturable absorption and two-photon absorption of the thin films containing the quantum dots (QD) of several metal sulfides and selenides (Ag 2 S, PbS, Ag 2 Se, and PbSe) are studied using the 1030 nm and 515 nm, 200 fs probe pulses. The prevailing role of saturable absorption and two-photon absorption in films was determined by varying the intensity of the probe pulses. The nonlinear optical parameters of the above processes are calculated. The strong two-photon absorption in PbS and PbSe QD films in the case of the 515 nm probe pulses is revealed. The growth of the nonlinear absorption in the QD films compared to the colloids containing similar species is attributed to the growing influence of the local field introduced by QDs in the films. The potential applications of the studied QD films are discussed.