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Nonlinear propagation of strong multi-mode fields
KTH, Tidigare Institutioner, Kemi.
KTH, Tidigare Institutioner, Bioteknologi.ORCID-id: 0000-0003-1269-8760
KTH, Tidigare Institutioner, Bioteknologi.ORCID-id: 0000-0002-1763-9383
2003 (engelsk)Inngår i: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 36, s. 3761-3774Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We develop a strict theory of nonlinear propagation of few interacting stronglight beams. The key idea of our approach is a self-consistent solution ofthe nonlinear wave equation and the density matrix equations of the materialbeyond the rotatory wave approximation. We assume a Fourier expansion ofthe density matrixwhich goes beyond the conventionalTaylor expansions of thepolarization over the field amplitudeswhich is inadequate for the field strengthsthat we are interested in. Two qualitatively different situations are considered,with and without phase matching. Unlike in our previous paper (Baev et al2003 J. Opt. Soc. Am. B at press) devoted to the three-photon (TP) absorptioninduced upconverted lasing, we obtain here a strict solution for the nonlinearinteraction between different light beams. The general theory is applied to anumerical study of the role of saturation in TP photoabsorption by an organicchromophore in solution.

sted, utgiver, år, opplag, sider
2003. Vol. 36, s. 3761-3774
Emneord [en]
2-photon excitation, absorption, dynamics, memory, pulses, media
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-5485DOI: 10.1088/0953-4075/36/18/305ISI: 000185966200006OAI: oai:DiVA.org:kth-5485DiVA, id: diva2:9868
Merknad
QC 20100906Tilgjengelig fra: 2006-03-15 Laget: 2006-03-15 Sist oppdatert: 2017-11-21bibliografisk kontrollert
Inngår i avhandling
1. Pulse Propagation in Nonlinear Media and Photonic Crystals
Åpne denne publikasjonen i ny fane eller vindu >>Pulse Propagation in Nonlinear Media and Photonic Crystals
2006 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The present thesis is devoted to theoretical studies of pulse propagation of light through linear and nonlinear media, and of light-induced nuclear dynamics.

The first part of the thesis addresses propagation of light pulses in linear periodical media - photonic crystals. The main accent was put on studies of the angular properties of two qualitatively different types of photonic crystals: holographic photonic crystals, and impurity band based photonic crystals. The anisotropy of band structure, group velocity and pulse delay with respect to the light polarization are analyzed.

In the second part of the thesis a strict theory of nonlinear propagation of a few strong interacting light beams is presented. The key idea of this approach is a self-consistent solution of the nonlinear wave equation and the density matrix equations of the material. This technique is applied to studies of dynamics of cavityless lasing generated by ultra-fast multi-photon excitation. It is shown that interaction of co- and counter-propagating pulses of amplified spontaneous emission (ASE) affects the dynamics and efficiency of nonlinear conversion. Our dynamical theory allows to explain the asymmetric spectral properties of the forward and backward ASE pulses, which were observed in recent experiment with different dye molecules. It is shown that the ASE spectral profile changes drastically when the pump intensity approaches the threshold level. The effect of the temporal self-pulsation of ASE is studied in detail.

The third part of the thesis is devoted to light-induced nuclear dynamics. Time- and frequency-resolved X-ray spectroscopy of molecules driven by strong and coherent infrared (IR) pulses shows that the phase of the IR field strongly influences the trajectory of the nuclear wave packet, and hence, the X-ray spectrum. Such a dependence arises due to the interference of one (X-ray) and two-photon (X-ray + IR) excitation channels. The phase of the light influences the dynamics also when the Rabi frequency approaches the vibrational frequency, breaking down the rotating-wave approximation. The probe X-ray spectra are also sensitive to the delay time, the duration, and the shape of the pulses. The evolution of the nuclear wave packets in the dissociative core-excited state affects the dynamics of resonant Auger scattering from fixed-in-space molecules. One of the important dynamical effects is the atomic-like resonance which experiences electronic Doppler shift. We predict that the scattering of the Auger electrons by nearby atoms leads to new Doppler shifted resonances. These extra resonances show sharp maxima in the bond directions, which makes them very promising as probes for local molecular structure using energy and angular resolved electron-ion coincidence techniques. Our theory provides prediction of several new effects, but also results that are in good agreement with the available experimental data.

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2006. s. x, 49
Emneord
Photonic Crystals, Nonlinear optics, X-ray spectroscopy
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-3886 (URN)91-7178-275-3 (ISBN)
Disputas
2006-03-31, FB42, AlbaNova, Roslagstullsbaken 21, Stockholm, 10:00
Opponent
Veileder
Merknad
QC 20100906Tilgjengelig fra: 2006-03-15 Laget: 2006-03-15 Sist oppdatert: 2011-11-23bibliografisk kontrollert
2. Pulse propagation in photonic crystals and nonlinear media
Åpne denne publikasjonen i ny fane eller vindu >>Pulse propagation in photonic crystals and nonlinear media
2005 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The present thesis is devoted to theoretical studies of light pulse propagation through different linear and nonlinear media. One dimensional holographic photonic crystals and one dimensional impurity band based photonic crystals are investigated as linear media. The effects of angular dependence of the band structures and pulse delay with respect to the light polarization are analyzed. A strict theory of nonlinear propagation of a few strong interacting light beams is presented and applied in the field of nonlinear optics. The key idea of this approach is a self-consistent solution of the nonlinear wave equation and the density matrix equations of the material beyond the so-called rotating wave approximation. The results of numerical studies led to a successful interpretation of recent experimental data [Nature, 415:767, 2002]. A theoretical study of the NO molecule by means of two-color infrared -- X-ray pump probe spectroscopy is presented. It was found that the phase of the infrared field strongly influences the trajectory of the nuclear wave packet, and hence, the X-ray spectrum. The dependence of the X-ray spectra on the delay time, the duration and the shape of the pulses are studied.

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2005. s. iii, 32
Emneord
Theoretical chemistry, Teoretisk kemi
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-351 (URN)91-7178-023-8 (ISBN)
Presentation
2005-05-24, Sal FB42, AlbaNova, Roslagstullssbacken 21, Stockholm, 10:00
Veileder
Merknad
QC 20101207Tilgjengelig fra: 2005-08-01 Laget: 2005-08-01 Sist oppdatert: 2011-11-23bibliografisk kontrollert

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Kimberg, ViktorÅgren, Hans

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