Third-order Nonlinear Components Research Articles

Theoretical insights into size and dielectric confinement: Unraveling real and imaginary parts of the effective complex dielectric function in spherical multilayered quantum dots with oxide interfaces

A quantitative numerical exploration is conducted to scrutinize the combined effects of size and dielectric confinement consequences on the electronic and optical characteristics of spherical multilayered quantum dot CdSe/ZnS/CdSe/ZnS (SMLQD) and its inverted configuration ZnS/CdSe/ZnS/CdSe (ISMLQD) buried into two oxides: HfO2 and SiO2. By employing the effective mass approximation (EMA) and the density matrix approach (DMA), the derived quantized electron energy states and their associated wave functions were obtained by solving the Schrödinger equation in a spherical coordinates. The dipole transition element, both real and imaginary parts of the effective complex dielectric function (ECDF) as well as its linear, nonlinear and total counterparts are brought out for various values of inner core radii, number density of QDs and incident photon intensity. In addition, a specific analysis of electron probability distributions is provided to gain a clearer understanding of the underlying physical factors. Our findings point to a notable influence of these mentionned factors on the computed coefficients. The study unveils that the dielectric mismatch occurring at the system/oxide interfaces plays a crucial role in modifying the electronic structure and a substantial impact on both linear and third-order nonlinear components is witnessed.

Signal transmission in the catfish retina. II. Transmission to type-N cell.

Responses from channel catfish type-N (sustained amacrine) cells were evoked either by step changes in illuminance, i.e. brightening or dimming from a mean illuminance, or by a white-noise modulated light stimulus. Current injected into the horizontal-cell soma or axon produced responses in type-N cells that were very similar to those produced by light stimuli. Light- and current-evoked responses had linear and second- and third-order nonlinear components; the former contributed 40-50%, whereas the latter contributed 20-30% to the total response. The remainder of the response could have been due to higher-order nonlinearities or to intrinsic as well as extrinsic noise. Nonlinear components in the light- and current-evoked responses were sharp transient peaks, which were prominent in white-noise-evoked responses, and oscillatory wavelets. The high-frequency components in the cell's response, which result from nonlinearity, were absent in the responses from bipolar and horizontal cells. The nonlinear responses were predicted by the second- and third-order kernels. The type-N cell response was complex because the response had both linear and nonlinear components, and because of the complexities of second- and, probably, third-order kernels. The cell's complex response reflects the complex nature of the cell's function as well as its synaptic organization.