Enhancement of Two-Photon Absorption Cross Section in CdSe Quantum Rods

Nonlinear optical properties of semiconducting CdSe quantum rods (QRs), with three various aspect ratios, were examined in a wide wavelength range using femtosecond Z-scan technique. The two-photon absorption cross section σ2 was found to be as large as 164 000 GM at the wavelength of 750 nm: about 4 times larger than that expected for CdSe quantum dots of the same mass. On the basis of the obtained dispersion of the two-photon absorption cross section, we have selected wavelength ranges for optimal excitation of two-photon-induced emission. We have also studied the luminescence kinetics using degenerate pump–probe and time-correlated single-photon counting techniques. A strong influence of semiconducting CdSe rods morphology on their steady-state and time-resolved optical properties was found.