Aleksey S. Tsipotan

Laser-induced wavelength-controlled self-assembly of colloidal quasi-resonant quantum dots.

Self-assembly of colloidal semiconductor quantum dots controlled solely by laser-induced interaction is demonstrated for the first time. Pairs of CdTe nanoparticles are formed under irradiation with nanosecond pulses at wavelengths 555 or 560 nm. Formation of pairs is justified by corresponding changes of absorption spectra. Conditions of the experiment are in excellent agreement with those predicted by the theory of laser-induced dipole-dipole interaction of QDs. The fraction of QDs assembled into pairs is up to 47%.

Simulating the absorption spectra of pairs of nanoparticles

Absorption spectra of pairs of particles with single resonance transitions are simulated in the dipole-dipole approximation. The results can be used in analyzing the spectra of samples obtained in studying the formation of pairs using quasi-resonant laser radiation.

Laser-induced Interaction of Multilevel Quantum Dots

A theoretical model is developed for describing the laser-induced interaction of a pair of multilevel semiconductor quantum dots. Spectral dependencies of interaction energy are calculated in dipole-dipole approximation for a pair of CdSe quantum dots in a quasi-resonant laser field, for cases of two identical quantum dots and those with differing transition wavelengths. Interaction energy of pair of multilevel quantum dots in the long-wavelength potential well is much higher than that of pair of two-level quantum dots. The increase of difference of resonance wavelengths of two interacting quantum dots leads to decrease of the potential well depth.