Enhanced two-photon absorption of CdS nanocrystal rods

In this letter we report that CdS nanocrystals are reshaped into an elongated rod form for increasing two-photon absorption. CdS quantum rods with uniform rod dimensions have been synthesized and their two-photon absorption cross section in solution has been characterized using the z -scan method and the two-photon induced fluorescence study. The absorption cross section was found to be 20.9x10-46 cm4 /s photon-1 under two-photon excitation at wavelength 800 nm, which is an order of magnitude larger than that of CdS quantum dots of similar diameters. The higher two-photon absorption coefficient establishes the potential of this class of quantum rods for various photonic applications.