Two-photon absorption in semiconductor nanocrystals

Banfi, G. P.; Degiorgio, Vittorio; Ghigliazza, M.; Tan, Hui Ming; Tomaselli, Alessandra

doi:10.1103/physrevb.50.5699

Cited by 49 publications

(30 citation statements)

References 13 publications

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“…However the experimental result [2] does not support this result. Since then TPA spectra of nanocrystallites has been attracting attention of researchers.…”

Section: Introductioncontrasting

confidence: 52%

“…Such a large scale calculation has been impossible with conventional algorithms. Therefore the present result will be an important step to solve the controversy related to direct-gap nanocrystallites [1,2].…”

Section: Discussion and Summarymentioning

confidence: 99%

“…In the following we show the effectiveness of this algorithm by applying it to the TPA spectra of indirect-gap nanocrystallites. Though this result does not solve the controversy related to direct-gap nanocrystallites [1,2], it will be an important step toward it.…”

Section: Introductionmentioning

confidence: 99%

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Non-degenerate two photon absorption spectra of Si nanocrystallites

Iitaka¹,

Ebisuzaki²

1999

Microelectronic Engineering

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“…However the experimental result [2] does not support this result. Since then TPA spectra of nanocrystallites has been attracting attention of researchers.…”

Section: Introductioncontrasting

confidence: 52%

Section: Discussion and Summarymentioning

confidence: 99%

See 1 more Smart Citation

Non-degenerate two photon absorption spectra of Si nanocrystallites

Iitaka¹,

Ebisuzaki²

1999

Microelectronic Engineering

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“…78.20.Bh The measurement of two-photon absorption coefficient [1] yields different information from the single-photon absorption measurement, since the physical processes involved and selection rules are different. Because of this, there has always been a lot of interest in two-photon absorption of various molecules, crystals and solids [2][3][4][5][6][7][8][9]. To compare against the experimental data, one would like to have theorerical calculations based on some realistic model of the material.…”

mentioning

confidence: 99%

Fast algorithm for calculating two-photon absorption spectra

et al. 1999

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We report a numerical calculation of the two-photon absorption coefficient of electrons in a binding potential using the real-time real-space higher-order difference method. By introducing random vector averaging for the intermediate state, the task of evaluating the two-dimensional time integral is reduced to calculating two one-dimensional integrals. This allows the reduction of the computation load down to the same order as that for the linear response function. The relative advantage of the method compared to the straightforward multi-dimensional time integration is greater for the calculation of non-linear response functions of higher order at higher energy resolution. 78.20.Bh The measurement of two-photon absorption coefficient [1] yields different information from the single-photon absorption measurement, since the physical processes involved and selection rules are different. Because of this, there has always been a lot of interest in two-photon absorption of various molecules, crystals and solids [2][3][4][5][6][7][8][9]. To compare against the experimental data, one would like to have theorerical calculations based on some realistic model of the material. However, since the twophoton absorption is a typical non-linear optical process, its realistic modeling has always proved difficult for large complex systems [2][3][4][5][6].A powerful method that has come to be used widely for large quantum systems is the real-time real-space higherorder difference method [10,11], in which the real-space is represented by discrete mesh points, and the time development of a system is solved by numerically integrating the Schrödinger equation for discrete time steps. The energy levels and energy eigenstates are obtained by Fourier analyzing the numerical solution. The memory requirement scales linearly with the number of basis states N compared to N 2 for matrix diagonalization, and the method has proved effective in solving large quantum systems that cannot be solved by conventional methods [11,12]. So far, the large computation load has meant that the actual application of the method has been made primarily to the calculation of linear response functions of one-particle systems [10,11]. Nevertheless, the potential scale advantage of the method when applied to large systems invites the speculation that the development of the method will be essential in making the calculation of non-linear response functions of complex many-body quantum systems feasible.In this article, we report a trial application of the method to the calculation of the two-photon absorption coefficient of non-interacting electrons trapped by a binding potential and exposed to monochromatic light of frequency ω.The two-photon absorption coefficient is given by [1]where H is the unperturbed hamiltonian of the system, r is the electron coordinate operator, η is the frequency resolution, V is the volume of the system, the summation with respect to the initial state |E i must be taken over all states below the Fermi level E F , and the summation wit...

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“…In contrast to the bulk material, nanoparticles have their own optical absorption characteristics, due to the confinement of the atoms in a tiny volume [7,8]. This geometry and dimension (nanometers) implies that a large fraction of atoms of the nanoparticle remain at the surface, being available to interact with the optical radiation field.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the optical absorption of a magnetic colloid from the thermal to the electronic time-scale regime: measurement of the free-carrier absorption cross-section

et al. 2012

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2012Investigation of the optical absorption of a magnetic colloid from the thermal to the electronic time-scale regime: measurement of the free-carrier absorption cross-section JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B: OPTICAL PHYSICS, WASHINGTON, v. 29, n. 3, pp. 280-285, 2012 The free-carrier absorption cross-section σ of a magnetic colloid composed of magnetite nanoparticles dispersed in oil is obtained by using the Z-scan technique in different experimental conditions of the laser beam. We show that it is possible to obtain σ with picosecond pulsed and millisecond chopped beams with pulse frequencies smaller than about 30 Hz. For higher pulse frequencies, the heating of the colloidal system triggers the appearance of the Soret effect. This effect artificially increases the value of σ calculated from the experimental results. The limits of the different experimental setups are discussed.

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Two-photon absorption in semiconductor nanocrystals

Cited by 49 publications

References 13 publications

Non-degenerate two photon absorption spectra of Si nanocrystallites

Non-degenerate two photon absorption spectra of Si nanocrystallites

Fast algorithm for calculating two-photon absorption spectra

Investigation of the optical absorption of a magnetic colloid from the thermal to the electronic time-scale regime: measurement of the free-carrier absorption cross-section

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