Three-photon excitation of quantum dots with a telecom-band ultrafast fiber laser

We demonstrate three-photon excitation in quantum dots with a mode-locked fiber laser operating in the telecommunications band. We compare spectra and intensity dependence of fluorescence from one- and three-photon excitation of commercially available 640-nm quantum dots, using a 372-nm diode laser for one-photon excitation and 116-fs pulses from a mode-locked fiber laser with a center wavelength of 1,575 nm for three-photon excitation.