  We propose to achieve super-resolution in far-field imaging by use of
dual-dye-doped nanoparticles. The nanoparticles with a diameter of a few
nanometers are co-doped with two types of dye molecules, namely, Cy3 and Cy5,
at a controllable ratio. Due to the short distances between the dye molecules
confined in the nanoparticles, Forster resonant energy transfer can occur
between the Cy3 and Cy5 molecules with high efficiency. Therefore, the Cy5
molecules can quench the fluorescence emission from the Cy3 molecules in the
outer region of focal spot of the excitation beam, thereby enhancing the
resolution of imaging.
