Intensity-dependent absorption and luminescence in semiconductor-doped glasses

Kull, M.; Coutaz, Jean‐Louis

doi:10.1364/josab.7.001463

Cited by 50 publications

(16 citation statements)

References 30 publications

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“…The power dependence of the detected signal is shown in Fig. 7 and agrees very well with the dependence described by Eqn (31). Thus, we conclude that the detected signal at angular frequency ω sig D 2ω p ω s corresponds to the expected four-wave mixing process.…”

Section: Resultssupporting

confidence: 85%

Spectral lineshape analysis of four-wave mixing spectra and its application to quasi-zero-dimensional II-VI semiconductor crystallites

Bischof

Lermann

Materny

et al. 1999

J. Raman Spectrosc.

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Theoretical and experimental investigations are presented in order to analyze the lineshape of fourwave mixing spectra recorded by means of electronically resonant folded BOXCARS spectroscopy (special technique of CARS, coherent anti-Stokes Raman scattering). The theoretical framework presented is based on the quantum-mechanical expression of the non-linear third-order susceptibility. In order to obtain model equations those contributions of the third-order susceptibility which give rise to strong electronic resonance enhancement were exclusively used. The participation of two-photon resonances and the inhomogeneous broadening of the electronic transitions is taken into account. The theoretical background presented was applied to a semiconductor model system consisting of quasi-zero-dimensional CdS x Se 1−x nanocrystallites. The inhomogeneous broadening of this low-dimensional system is mainly caused by the size distribution of the nanocrystallites. The lineshapes of the experimentally obtained four-wave mixing spectra are well described within the theoretical framework and the homogeneous linewidth of the resonantly excited electronic state can be deduced.

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Section: Resultssupporting

confidence: 85%

Spectral lineshape analysis of four-wave mixing spectra and its application to quasi-zero-dimensional II-VI semiconductor crystallites

Bischof

Lermann

Materny

et al. 1999

J. Raman Spectrosc.

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“…This comparison was carried out in order to separate the photodarkening effects, which were extensively studied and discussed elsewhere. [16][17][18] The results shown in Fig. 8 confirm that lens formation induces no considerable change in luminescence intensity at the plateau or anywhere outside the lens area, which on this plot extends from approximately Ϫ50 to 50 m. Both curves follow the same profile attributed to photodarkening.…”

Section: Lens Interactionssupporting

confidence: 63%

Direct laser fabrication of dense microlens arrays in semiconductor-doped glass

Smuk¹,

Lawandy²

2000

Journal of Applied Physics

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A direct laser writing technique in semiconductor-doped glasses is used to fabricate microlens arrays with fill factors exceeding the close-packing limit for circular microlenses. This is achieved by both structural and thermal interactions between adjacent lenses during fabrication, which result in the formation of microlenses shaped in accordance with the translational symmetry of the array. The effect of nearest-neighbor interaction on various time scales is studied and shown to be critical to the distortions observed.

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“…The magnitude and the dynamics of the optical nonlinearities have been investigated with various experimental techniques, such as single-beam absorption saturation, [15] pump-probe measurements in the nanosecond, [4,6,7,9,10,16] picosecond, [5,17,18] and femtosecond regime, [4,19] and photon-echo experiments [11,14,20].…”

Section: Pacsmentioning

confidence: 99%

Section: Pacsmentioning

confidence: 99%

“…This latter effect is observed as "photodarkening" by strong laser illumination which leads to a weak broadband reduction of the linear transmission [15,21] and to drastically reduced lifetimes of optically excited carriers, resulting in a reduction of the luminescence First publ. in: Applied Physics B 62 (1996) intensity and of the carrier-induced absorption changes in the nanosecond time regime [16,[21][22][23].…”

Section: Pacsmentioning

confidence: 99%

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Ultrafast dynamics of carrier-induced absorption changes in highly-excited CdSe nanocrystals

et al. 1996

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Abstract. We use femtosecond time-resolved transmission spectroscopy to study the density and time dependence of transient absorption changes of CdSe nanocrystals. Our data show pronounced absorption saturation up to complete bleaching of the lowest optical transition. At high carrier density the nonlinear spectra show several peaks that can be related to the two lowest quantized electron states. Thetime dependence of the carrier-induced absorption changes indicates an ultrafast relaxation process within the strongly broadened absorption lines. 78.47.+p; 73.20.Dx; 71.35.+z In recent years, there has been a strong interest in lowdimensional semiconductor structures such as quantum wells, quantum wires, and quantum dots. The electronic states in these artificial materials are strongly influenced by size quantization effects, which occur when the dimensions of the structures become comparable to or smaller than the exciton Bohr radius aB. Then, the electronic and optical properties of the structures become determined by their geometry. Thus, the controlled fabrication of low-dimensional semiconductor structures may allow to obtain materials with predefined properties. PACS:In addition, size quantization has been shown to lead to a significant enhancement of excitonic effects and to strongly enhanced optical nonlinearities in two-dimensional quantum wells, where the carriers are confined in only one dimension [1]. It can be expected that a confinement of carriers in two or three dimensions will lead to a further enhancement of the optical nonlinearities. Therefore, semiconductor quantum dots appear as a promising new material for nonlinear optical applications. It has been found that semiconductor crystallites with radii on the order of a few nanometer, denoted as nanocrystals (NCs), can be rather easily produced in semiconductor-doped glasses (which are commercially available as color-glass filters) or in organic solution [2][3][4]. The linear absorption of such samples generally shows a correlation with the average NC size, as the lowest absorption feature shifts towards higher energies with decreasing size [3,[5][6][7][8][9][10][11]. While this clear sign of size quantization is easily observed, the absorption spectra of semiconductordoped glasses usually fail to show sharp exciton peaks (in contrast with two-dimensional quantum wells) or even wellseparated absorption lines that reflect the expected discrete energy spectrum of a "zero-dimensional" structure. It is commonly accepted that the presence of discrete electronic states is masked in the linear absorption by strong homogeneous and inhomogeneous broadening. The nanocrystals may vary in size, geometry, and chemical composition. These variations cause a strong inhomogeneous broadening of the optical transitions. Variations of the NC size are typically on the order of 25% [12]. This value may be reduced to a few percent by sophisticated preparation techniques, but even then the size distribution has a significant influence on the optical properties [4,10,1...

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Intensity-dependent absorption and luminescence in semiconductor-doped glasses

Cited by 50 publications

References 30 publications

Spectral lineshape analysis of four-wave mixing spectra and its application to quasi-zero-dimensional II-VI semiconductor crystallites

Spectral lineshape analysis of four-wave mixing spectra and its application to quasi-zero-dimensional II-VI semiconductor crystallites

Direct laser fabrication of dense microlens arrays in semiconductor-doped glass

Ultrafast dynamics of carrier-induced absorption changes in highly-excited CdSe nanocrystals

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