Third-order nonlinear optical properties of a novel series of D-π-A pyrene-aldehyde derivatives

A series of mono-substituted pyrene derivatives having a pyrene mesogenic core and aldehyde group peripherals were designed and synthesized, which had typical D-[Formula: see text]-A structures. Photophysical properties of the compounds were characterized by UV/Vis spectroscopy and the third-order nonlinearities of the compounds were studied by “open aperture” and “closed aperture” [Formula: see text]-scan techniques. Both of the compounds showed typical nonlinear absorptions and refractions, and the third-order nonlinear susceptibilities have been found to be very high in all cases. The significant nonlinear optical response combined with the possibility to further modify it, by changing the electron acceptor and the electron-donor groups, suggests that these systems can prove to be important candidates for a variety of photonic/optoelectronic applications.

Nonlinear Absorptions of CdSeTe Quantum Dots under Ultrafast Laser Radiation

The oil-soluble alloyed CdSeTe quantum dots (QDs) are prepared by the electrostatic method. The basic properties of synthesized CdSeTe QDs are characterized by UV-Vis absorption spectroscopy, photoluminescence spectroscopy, inductively coupled plasma mass spectrometry, and transmission electron microscope. The off-resonant nonlinear optical properties of CdSeTe QDs are studied by femtosecondZ-scan at 1 kHz (low-repetition rate) and 84 MHz (high-repetition rate). Nonlinear absorption coefficients are calculated under different femtosecond laser excitations. Due to the long luminescent lifetime of CdSeTe QDs, under the conditions of high-repetition rate, for open-aperture curve, heat accumulation and bleaching of ground state are responsible for the decrease of two-photon absorption (TPA) coefficient.

Stack emission monitoring using non-dispersive infrared spectroscopy with an optimized nonlinear absorption cross interference correction algorithm

In this paper, we present an optimized analysis algorithm for non-dispersive infrared (NDIR) to in situ monitor stack emissions. The proposed algorithm simultaneously compensates for nonlinear absorption and cross interference among different gases. We present a mathematical derivation for the measurement error caused by variations in interference coefficients when nonlinear absorption occurs. The proposed algorithm is derived from a classical one and uses interference functions to quantify cross interference. The interference functions vary proportionally with the nonlinear absorption. Thus, interference coefficients among different gases can be modeled by the interference functions whether gases are characterized by linear or nonlinear absorption. In this study, the simultaneous analysis of two components (CO2 and CO) serves as an example for the validation of the proposed algorithm. The interference functions in this case can be obtained by least-squares fitting with third-order polynomials. Experiments show that the results of cross interference correction are improved significantly by utilizing the fitted interference functions when nonlinear absorptions occur. The dynamic measurement ranges of CO2 and CO are improved by about a factor of 1.8 and 3.5, respectively. A commercial analyzer with high accuracy was used to validate the CO and CO2 measurements derived from the NDIR analyzer prototype in which the new algorithm was embedded. The comparison of the two analyzers show that the prototype works well both within the linear and nonlinear ranges.

Stack emission monitoring using non-dispersive infrared with optimized nonlinear absorption cross-interference correction algorithm

In this paper, we present an optimized analysis algorithm for non-dispersive infrared (NDIR) to monitor stack emissions. The newly developed analysis algorithm simultaneously compensates for nonlinear absorption and cross-interference between different gases. We present a mathematical derivation for the measurement error caused by variations in interference coefficients when nonlinear absorption occurs. The optimized algorithm is derived from a classical one and uses interference functions to quantify cross-interference. The interference functions vary proportionally with the nonlinear absorption. Thus, interference coefficients among different gases can be modeled by the interference functions whether gases are characterized by linear or nonlinear absorption. In this study, the simultaneous analysis of two components (CO2 and CO) serves as an example for the validation of the optimized algorithm. The interference functions in this case can be obtained by least-squares fitting with three-order polynomials. Experiments show that the results of cross-interference correction are improved significantly by utilizing fitted interference functions when nonlinear absorptions occur. The dynamic measurement ranges of CO2 and CO are improved by about a factor of 1.8 and 3.5, respectively. A commercial NDIR multi-gas analyzer with high accuracy was used to validate the CO and CO2 measurements derived from the NDIR analyzer prototype in which the new cross-interference correction algorithm was embedded. Both measurements well agreed.

Extinction and Decay Estimates of Solutions for thep-Laplacian Equations with Nonlinear Absorptions and Nonlocal Sources

We investigate the extinction and decay estimates of thep-Laplacian equations with nonlinear absorptions and nonlocal sources. By Gagliardo-Nirenberg inequality, we obtain the sufficient conditions of extinction solutions, and we also give the precise decay estimates of the extinction solutions.

NONLINEAR OPTICAL PROPERTIES OF DOPED ZnS QUANTUM DOTS

Three- and four-photon nonlinear absorptions are reported by z-scan techniques in ZnS and 1% Mn 2+ doped ZnS quantum dots (QDs) with 532 and 1064 nm radiations, respectively, obtained from a Q-switched Nd :YAG laser fundamental and its second harmonic radiation. The obtained maximum value of the 3PA coefficient in the doped ZnS QDs is ~105 times that of bulk ZnS . Also, intensity-dependent saturation of 3PA has been observed and the measured experimental data are explained theoretically using a 3PA saturation model and the characteristic saturation intensity is estimated to be 0.92±0.04 GW/cm2.