Analytical results for nonlinear optical signals from quantum dots coupled to phonons

• Published in: Physica Status Solidi (b) Vol. 238; no. 3; pp. 581 - 588
• Main Authors: Axt, V. M., Krummheuer, B., Vagov, A., Kuhn, T.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Berlin WILEY-VCH Verlag 01.08.2003; WILEY‐VCH Verlag; Wiley
• Subjects: 42.65.-k; 63.20.Kr; 63.22.+m; 78.47.+p; 78.67.Hc; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Lattice dynamics; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Phonon-electron and phonon-phonon interactions; Phonons and vibrations in crystal lattices; Physics; Quantum dots; Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter; Acoustical phonons; Gallium arsenides; Inorganic compounds; Line shape; Four-wave mixing; Quantum dots; Theoretical study; Oscillations; Binary compounds; Continuum; Time dependence; Linear polarization; Excitation spectrum; Nonlinear optics; III-V semiconductors
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.200303175

The impact of pure dephasing processes on the optically induced nonlinear dynamics of quantum dots is analyzed. Concentrating on small dots pure dephasing can be studied analytically in the limit of ultrafast excitation. General conclusions from the analysis of the closed form formulas include the prediction that four‐wave‐mixing (FWM) spectra of single dots change from asymmetric to symmetric lineshapes with increasing pulse delay. Furthermore, in contrast to phenomenological dephasing models the delay dependence of the time integrated FWM amplitude |PFWM| generated by a strongly inhomogeneously broadened ensemble deviates from the real time dependence of |Plin|2, where Plin is the linear polarization emitted by a single dot. Numerical results are presented for FWM signals from dots coupled to bulk acoustic phonons. Surprisingly, the initial decay time of the signal depends non‐monotonously on the temperature. In addition, it is shown that for certain material parameters the coupling to the smooth continuum of acoustic phonons may result in pronounced oscillations.