Narrow Results

Dipole and cavity field transient spectra are investigated for a modified Jaynes-Cummings (JC) model due to the presence of a second harmonic generation (SHG) cavity field. For initially de-excited atom and field in a coherent state, detuning effects due to SHG affects the symmetry and splitting structure of both spectra.

Mentioned communication explores the modification in properties of Zinc Thiourea Sulphate (ZTS) crystal due to L-Threonine (LT) addition. Superior quality LT-doped ZTS crystal with 0.5 M% concentration of LT was grown by the slow evaporation solution growth technique. Powder X-ray diffraction technique was applied to study the cell parameters which confirmed orthorhombic crystal structure of both pure and LT-ZTS crystal with slight variation in cell parameters. Shimatzu make spectrophotometer confirmed the UV-Visible spectral analysis in the range of 200–900 nm which affirmed the 94% transmittance, enhanced bandgap value (4.72 eV), lower cut-off value (246 nm) and lower optical constants viz. extinction coefficient, polarizability, refractive index, and reflectance of LT-ZTS crystal. The higher second harmonic generation (SHG) efficiency of LT-doped ZTS was pointed by Kurtz Perry powder method (3.06 times of pure ZTS crystal and 3.62 times of KDP crystal) using Nd: YAG laser. The colour centered emission and electronic purity of parent and doped ZTS crystals were examined which resulted in the violet emission in visible region for both pure and LT-ZTS crystals. Z-scan technique is used to identify the Kerr lensing nonlinearity in pure and LT-doped ZTS crystal. Close aperture Z-scan curve demonstrated negative refraction nonlinearity (self-defocusing nature) for pure and positive refraction nonlinearity (self-focusing nature) for LT-ZTS crystal. Calculated value of refraction nonlinearity n2 is −2.2 × 10${}^{-11}$ cm²/W for pure ZTS and $+$4.99 × 10${}^{-12}$ cm²/W for LT-ZTS crystal. Open aperture Z-scan showed reverse saturable absorption effect (RSA) in pure ZTS and saturable absorption effect (SA) in LT-ZTS crystal. The $\beta$ value is 2.85 × 10${}^{-5}$ cm/W for pure ZTS and 3.92 × 10${}^{-5}$ cm/W for LT-ZTS crystal. The $\chi$3 of ZTS crystal is 6.133 × 10${}^{-5}$ cm/W and 1.655 × 10${}^{-4}$ cm²/W for LT-ZTS crystal. The transition in TONLO parameters is observed due to doping of LT in ZTS. The obtained parameters indicated the superiority of LT-ZTS for application in distinct laser stabilization systems, UV shelter and NLO applications.

Single crystals of pure and various amount of L-lysine doped KDP crystals were grown from aqueous solution. The doping of L-lysine was confirmed by CHN analysis and FT-IR spectroscopy. Powder XRD was carried out to assess the single phase nature of the samples. The effect of doping on thermal stability of the crystals was carried out by TGA and the kinetic and thermodynamic parameters of dehydration were evaluated. It was found that as the amount of doping of amino acid, L-lysine, increased the thermal stability of the grown crystals decreased. However, the second-harmonic generation (SHG) efficiency of Nd:YAG laser and UV-vis spectroscopy studies indicated that as the L-lysine doping increased in KDP crystals the SHG efficiency and optical transmission percentage increased. The dielectric constant and the dielectric loss of L-lysine doped KDP crystals are lower than the pure KDP crystals. Hence L-lysine doped KDP crystals are found to be more beneficial from an application point of view as compared to pure KDP crystals. The results are discussed.

2-Amino-5-nitropyridinium halides (2A5NPBr)/(2A5NPCl) were synthesized by dissolving 2-amino-5-nitropyridine in hydrobromic/hydrochloric acid. Nanoparticles of 2A5NPBr and 2A5NPCl were attained by hydrothermal method. For comparison and estimation of mechanical properties, single crystals of the samples were grown by slow evaporation process. SEM analysis shows the formation of nanoparticles of 2A5NPBr and 2A5NPCl with average grain size of 50 and 100nm, respectively. UV-Vis analysis reveals that the materials possess low cut-off wavelength and a wide optical transmission window. By Vickers test, the Meyer index (n) was estimated to be 1.33 for 2A5NPBr and 2.49 for 2A5NPCl crystals. The SHG efficiency of 2A5NPBr and 2A5NPCl nanoparticles was calculated to be 1.5 and 4.3 times that of well known NLO material KDP. The role of cations in demonstrating the desired NLO properties were discussed in detail.

Two major reasons limit porphyrins photonic applications: (i) the difficulty of handling them in liquid solutions and (ii) their degradation with long exposure to light. This necessitates the use of appropriate solid matrices to host the porphyrin compounds such as Nafion (117), a stable and inert ion exchange polymer. The first part of this publication confirms such a possibility. In addition to their effective NLO properties, an enhancement of the Soret and Q-bands' absorbance width have been observed by blending three different porphyrin molecules in the Nafion column matrix membrane. This is an important development towards achieving efficient photon-harvesting medium for possible application in photonic devices. The second part of this contribution reports on the self-assembly/molecular recognition of a specific class of porphyrins giving rise to tubular nano-systems with potential THG nonlinear properties.

L-Glycine Glycinium Hydrochloride Monohydrate (L-GGHCM), a new second-order nonlinear optical crystal, was produced using the slow evaporation process with double distilled water as a solvent. Powder XRD analysis was completed in order to identify the crystallinity sample. In the orthorhombic system with space group P${}_{212121}$, L-GGHCM expands in accordance with structural improvement. A single crystal XRD analysis discovered the extended framework architecture of L-GGHCM, a self-assembly process involving short-range and directed bonds, among many other interactions. The optical quality and transmission of the synthesized crystal were determined using UV–visible and fluorescence spectrum analysis. The effectiveness of L-GGHCM’s second harmonic generation is roughly 1.7 times compared to a standard potassium dihydrogen orthophosphate sample. Thermal analysis is used to study a material’s thermal stability and internal decomposition. L-glycine glycinium hydrochloride monohydrate crystal is shown to have good thermal stability.

The following sections are included:

• Introduction
• Linear vis-à-vis Nonlinear
• Nonlinear Equation of Ultrafast Optics: Mathematical Formulation of Propagation of Ultrafast Pulse in a Nonlinear Medium
• Solution of Nonlinear Optical Equation
• Further Discussion on Phase Matching Taking Example of SHG
• Further Discussion on Third-Order Processes
• Degenerate 4WM
• High Harmonic Generation (HHG)
• References
• Further Reading