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 1575 nm for three-photon excitation.Comment: 6 pages, 3 figure
