Origin Of Nonlinear Optical Effects Research Articles

Restructuring of plasmonic nanoparticle aggregates with arbitrary particle size distribution in pulsed laser fields

We have studied processes of interaction of pulsed laser radiation with resonant groups of plasmonic nanoparticles (resonant domains) in large colloidal nanoparticle aggregates having different interparticle gaps and particle size distributions. These processes are responsible for the origin of nonlinear optical effects and photochromic reactions in multiparticle aggregates. To describe photo-induced transformations in resonant domains and alterations in their absorption spectra remaining after the pulse action, we introduce the factor of spectral photomodification. Based on calculation of changes in thermodynamic, mechanical, and optical characteristics of the domains, the histograms of the spectrum photomodification factor have been obtained for various interparticle gaps, an average particle size, and the degree of polydispersity. Variations in spectra have been analyzed depending on the intensity of laser radiation and various combinations of size characteristics of domains. The obtained results can be used to predict manifestation of photochromic effects in composite materials containing different plasmonic nanoparticle aggregates in pulsed laser fields.

Experimental and theoretical studies of second harmonic generation for Bi2O2[NO3(OH)

The structural characteristics and optical properties of bismuth nitrate Bi2O2[NO3(OH)] (BINO) are investigated by experimental in combination with theoretical studies. The BINO crystal was obtained from the hydrothermal growth, and its UV–Vis absorption spectrum was measured. Second harmonic generation (SHG) experiments on powder sample show that BINO is a phase-matchable nonlinear optical crystal with a large powder SHG coefficient of 2.3pm/V, which is confirmed by the first-principles calculations. Moreover, the structural origin of nonlinear optical effects in BINO is given. Our studies reveal that BINO is a promising SHG crystal in the visible and infrared spectral region.

Nonlinear optical properties of transition metal acetylides and their derivatives*1

The nonlinear optical (NLO) properties of metal acetylide and vinylidene complexes are summarized, and molecular structure–NLO property trends are developed. The origin of NLO effects in molecules is presented, and the advantages and shortcomings of experimental procedures that have been used to measure optical nonlinearities for these complexes are discussed. Attempts to “switch” optical nonlinearities of acetylide or vinylidene complexes are summarized.

Description of Nonlinear Optics on an Atomic Scale

An examination is made of charge motion on an atomic scale in response to an applied electric field at optical frequencies to demonstrate the physical origin of nonlinear optical effects. In particular, second harmonic generation in a crystal of zinc blende structure is considered, and the zero and nonzero components of the nonlinear susceptibility tensor are obtained. Also, an estimate of the magnitude of the nonlinear susceptibility is made.