RESONANT OPTICS OF FRACTALS

Fractal objects can sustain strongly localized optical modes with high quality-factor. Intense local fields associated with the dipolar eigenmodes in fractals ultimately result in significant enhancement of a number of optical effects. In particular, such basic optical processes as Rayleigh and Raman scattering, degenerate four-wave mixing and harmonic generation, two-photon absorption and non-linear photoemission can be enhanced by several orders of magnitude in small-particle fractal composites and self-affine films.

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Effects of two-photon absorption on degenerate four-wave mixing in solutions of diphenyl polyenes

Optics Letters ◽

10.1364/ol.17.000716 ◽

1992 ◽

Vol 17 (10) ◽

pp. 716 ◽

Cited By ~ 18

Author(s):

P. A. Fleitz ◽

R. L. Sutherland ◽

T. Pottenger ◽

N. C. Fernelius ◽

L. V. Natarajan

Keyword(s):

Four Wave Mixing ◽

Photon Absorption ◽

Wave Mixing ◽

Two Photon Absorption ◽

Two Photon ◽

Degenerate Four Wave Mixing

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Subwavelength Localization of Optical Modes in Fractals

MRS Proceedings ◽

10.1557/proc-351-449 ◽

1994 ◽

Vol 351 ◽

Author(s):

Vladimir Shalaev ◽

R. Botet ◽

M. Moskovits

Keyword(s):

Nonlinear Optical ◽

Optical Excitation ◽

Four Wave Mixing ◽

Local Fields ◽

Wave Mixing ◽

Fractal Clusters ◽

Raman Light Scattering ◽

Optical Effects ◽

Optical Modes ◽

Very High

ABSTRACTResonant optical excitation of fractal clusters generates dipolar eigenmodes which are extremely localized within areas much smaller than the wavelength. The localization occurs due to the fractal morphology and accounts for the very high local fields leading to the huge enhancement of various optical effects. In particular, Rayleigh and Raman light scattering and, especially, nonlinear optical processes, such as 2-photon photoemission and degenerate four-wave mixing, are strongly enhanced in fractal clusters. The spatial distribution of the modes shows the frequency and polarization selectivity.

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Two-Photon Absorption and Degenerate Four-Wave Mixing Studies of Sulfide Semiconductor Nanoparticles in Polymeric Solutions

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.18197 ◽

2008 ◽

Vol 8 (3) ◽

pp. 1364-1370 ◽

Cited By ~ 1

Author(s):

Wenling Jia ◽

Fengqi Guo ◽

Elliot P. Douglas ◽

Wenfang Sun

Keyword(s):

Four Wave Mixing ◽

Semiconductor Nanoparticles ◽

Photon Absorption ◽

Wave Mixing ◽

Absorption Coefficients ◽

Third Order ◽

Two Photon Absorption ◽

Two Photon ◽

The Third ◽

Degenerate Four Wave Mixing

The two-photon absorption coefficients (β) and the third-order nonlinear susceptibilities (χ(3)) of several semiconductor nanoparticles (CdS, CdxAg1–xS, and core–shell CdS/Ag2S) that are confined and stabilized by random and block ionomers have been measured by nonlinear transmission and degenerate four-wave mixing techniques using 21 picosecond laser pulses at near-infrared spectral region. The imaginary part of the third-order nonlinear susceptibility that is related to the two-photon absorption coefficient was then calculated. The absorptive nonlinearity of the nanoparticles (2∼9 nm) was found to be dependent on the particle size, composition and wavelength, i.e., larger CdS particles exhibit higher two-photon absorption coefficients and the presence of Ag improves two-photon absorption of CdS nanoparticles. The obtained two-photon absorption coefficients of nanoparticles corrected for their volume fraction in solution are significantly greater that those of corresponding bulk semiconductors.

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