Nonlinear optical response of semiconductors in the independent-particle approximation

We report the first fully self-consistent calculations of the nonlinear optical properties of superlattices. The materials investigated are mono-layer superlattices with GaP grown on the the top of InP, AlP and GaAs (110) substrates. We use the full-potential linearized augmented plane wave method within the generalized gradient approximation to obtain the frequency dependent dielectric tensor and the second-harmonic-generation susceptibility. The effect of lattice relaxations on the linear optical properties are studied. Our calculations show that the major anisotropy in the optical properties is the result of strain in GaP. This anisotropy is maximum for the superlattice with maximum lattice mismatch between the constituent materials. In order to differentiate the superlattice features from the bulk-like transitions an improvement over the existing effective medium model is proposed. The superlattice features are found to be more pronounced for the second-order than the linear optical response indicating the need for full supercell calculations in determining the correct second-order response.

show abstract

“…61,62 We note that Eq. B3 of Ref 61 is incorrect and the correct form of this equation can be obtained from the sum of Eqs.…”

Section: Appendix A: Formalism For the Second-order Responsementioning

confidence: 99%

“…60 The formulae for calculating χ (2) (2ω, ω, ω) have also been presented before. 61,62,63,64 They are rewritten to improve the computational efficiency, and we compare the computing time for both sets of formulae in Appendix A. The SHG susceptibility obtained satisfies all the theoretical sum rules presented by Scandolo and Bassani.…”

mentioning

confidence: 99%

Linear and second-order optical response of III-V monolayer superlattices

2003

View full text Add to dashboard Cite

show abstract

“…Sipe and Ghahramani 34 and Aversa and Sipe 35 developed a formalism for the calculation of the second-order optical response of crystals in the independent particle approximation, and a more recent approach has been reported by Sipe and Shkrebtii 36 . Based on these works, Hughes and Sipe [37][38][39] presented a first-principles calculation of the second-order optical response functions, including self-energy corrections at the level of the scissors approximation.…”

Section: Introductionmentioning

confidence: 99%

Ab initiosecond-order nonlinear optics in solids: Second-harmonic generation spectroscopy from time-dependent density-functional theory

2010

View full text Add to dashboard Cite

We present in detail the formulation of the ab initio theory we have developed for the calculation of the macroscopic second-order susceptibility χ (2) . We find a general expression for χ (2) valid for any fields, containing the ab initio relation between the microscopic and macroscopic formulation of the second-order responses. We consider the long wavelength limit and we develop our theory in the Time-Dependent Density-Functional Theory framework. This allows us to include straightforwardly many-body effects such as crystal local-field and excitonic effects. We compute the Second-Harmonic Generation spectra for the cubic semiconductors SiC, AlAs and GaAs and starting from the Independent-Particle Approximation for χ (2) , we include quasiparticle effects via the scissors operator, crystal local-field and excitonic effects. In particular, we consider two different types of kernels: the ALDA and the "long-range" kernel. We find good agreement with other theoretical calculations and experiments presented in literature, showing the importance of very accurate description of the many-body interactions.

show abstract

“…(4.11) cancels with the real part of interband term resulting in a purely imaginary current [91]. With…”

Section: E Perturbation Approach Of the Phonon-assisted Quantitiesmentioning

confidence: 99%

“…Within the linear band regime, it can be shown that the third term of the current j(t) in Eq. (4.11) cancels with the real part of interband term resulting in a purely imaginary current in the Fourier space [91]. Finally, the absorption coe cient can be written as…”

Section: Transient Negative DI Erential Transmissionmentioning

confidence: 99%

Relaxation Dynamics in Graphene

Malić

Knorr

2013

Graphene and Carbon Nanotubes

View full text Add to dashboard Cite

In this thesis, the relaxation dynamics of nonequilibrium carriers in graphene is investigated. Based on the density matrix approach, the interaction of carriers with light, phonons and electrons is theoretically modelled. The resulting time-, momentum-, and angle-resolved simulation of the carrier dynamics enables the interpretation of recent experimental observations. Typically, the carrier relaxation has been accessed via high-resolution pump-probe experiments. Common to all studies is a bi-exponential decay of the pump-induced differential transmission (DT) spectrum. The fast decay component in the range of few tens of femtoseconds is assigned to an ultrafast Coulomb-dominated carrier redistribution towards a hot Fermi-Dirac distribution, whereas the slower decay component in the range of a picosecond reflects the equilibration between the electron and the phonon system. However, many studies report a zero-crossing after the initial decay in the transient DT spectrum, where the second decay component characterizes the recovering of the DT signal. In very good agreement with recent pump-probe experiment performed by the group of Prof. Manfred Helm (Helmholtz-Zentrum Dresden-Rossendorf), a microscopic explanation for the occurrence of transient negative differential transmission in graphene is found, where a detailed interplay of intraand interband absorption processes on the transient DT in graphene is investigated. In particular, phonon-assisted intraband processes are shown to lead to an enhanced absorption giving rise to the experimentally observed zero-crossing from positive to negative DT signals.In collaboration with the group of Prof. Theodore B. Norris (Michigan University, USA), theoretical studies combined with ultrafast time-resolved THz spectroscopy were performed to systematically investigate the hot-carrier dynamics in an array of graphene samples. The theory calculates explicitly the time-dependent response of the system to a THz probe pulse. The calculations reveal that the observed dynamics can be accounted for qualitatively without including any fitting parameters, phenomenological models or extrinsic effects. Specifically, the hot-carrier dynamics are governed by the coupling of extraordinarily efficient carrier-carrier and carrier-phonon interactions. Furthermore, the theory demonstrates that the simple Drude model is insufficient to fully account for the THz interactions.Beside pump-probe studies, the thesis presents the absorption spectra of mono-and bilayer graphene including the impact of the fully momentum-dependent optical and Coulomb matrix elements. In agreement with recent experiments, the absorbance of graphene is characterized by a frequency-independent value in the near-infrared spectral region and a pronounced peak in the ultraviolet region resulting from interband transition. In contrast to the linear band structure of graphene, the energy dispersion of bilayer graphene exhibits four parabolic bands resulting in interesting optical features: The absorbance exhibits in...

show abstract

Nonlinear optical response of semiconductors in the independent-particle approximation

Cited by 329 publications

References 16 publications

Linear and second-order optical response of III-V monolayer superlattices

Linear and second-order optical response of III-V monolayer superlattices

Ab initiosecond-order nonlinear optics in solids: Second-harmonic generation spectroscopy from time-dependent density-functional theory

Relaxation Dynamics in Graphene

Contact Info

Product

Resources

About