We report luminescence and optical limiting (OL) applications of pure and doped layered hybrid halide perovskite (LHHP). Rhodamine B (Rh B), an organic laser dye, was doped in bis(4-methoxybenzylammonium) tetra-chlorido cadmate (4MBA(2)CdCl(4)). A simple and cost-effective slow solvent evaporation technique was utilized for crystallization of the perovskites. Formation of both pure and doped 4MBA(2)CdCl(4) were confirmed from the X-ray diffraction (XRD) and Fourier transform infrared (FTIR) studies. 4MBA(2)CdCl(4) crystallized as a layered perovskite where organic layers (4MBA(+)) are sandwiched between the distorted inorganic CdCl4- octahedral layers. The perovskites are thermally stable up to 276 degrees C and are flexible up to a load of 50 g. Optical absorption of pure perovskite falls in UV region and is highly transparent for visible light. But, inclusion of Rh B reflected a new absorption peak in the visible region. Also, the luminescence under UV excitation of 4MBA(2)CdCl(4) modified due to doping of dye and it exhibit strong golden yellow luminescence. Nonlinear optical (NLO) properties of pure and doped 4MBA(2)CdCl(4) were also studied by Z-scan technique using 785 nm continuous wave (CW) laser. The perovskites exhibited reverse saturable absorption (RSA) and self-defocusing. Further, both perovskites demonstrate optical limiting properties with a low intensity threshold of 0.8 MW/m(2). Rh B incorporated 4MBA(2)CdCl(4) exhibit interesting and enhanced photoluminescence and OL behaviours.

We report temperature dependent photoluminescence (PL) and solvatochromic studies of 4-methoxybenzylammonium chloride (4-MBACl). The single crystals of 4-MBACl has been grown using slow solvent evaporation method under ambient conditions and have been confirmed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic studies. Thermal stability of the material has been analyzed by thermogravimetric (TG) and differential thermal analyzes (DTA). 4-MBACl crystal is photoluminescent with emission wavelength maximum at 300 nm. Exciton-phonon coupling in 4-MBACl is realized from temperature dependent PL studies. Changes in full width at half maximum (FWHM) of PL emission peak, intensity maximum (I-max) and wavelength maximum (lambda(max)) have been analyzed systematically between temperatures 290-10 K in order to understand the photophysical phenomenon behind the emission. Optical band gap (E-g) of 4-MBACl has been varied using solvent polarity, proticity and solution concentration. Interactions like OH-O, OH-pi and pi-pi stacking are explained to reason the notable shifts. (C) 2021 Elsevier B.V. All rights reserved.

We report pure potassium penta borate octa hydrate (PPB) and methyl orange dye-doped potassium penta borate octa hydrate (MOPPB) for optical limiting applications. The crystals were grown by slow evaporation solution growth technique at ambient conditions. The single crystal X-ray diffraction (SXRD) evinces the orthorhombic class of the pristine and MOPPB crystals. Formation of PPB and incorporation of MO dye in PPB was confirmed through Fourier transform infrared (FTIR) study. Calculated hardness number and stiffness constant with Vicker’s Micro hardness study portrays the soft nature of the title crystals. The decrease in bandgap of MOPPB is due to the additional energy levels introduced between the valence band and conduction band which in turn increases the net polarizability of the crystal. Relative second harmonic generation (SHG) efficiency of pure PPB and MOPPB is 0.45 times and 0.40 times that of SHG output of KDP. Z-scan studies shows that both crystals show reverse saturable absorption (RSA) ascribed due to two-photon absorption (TPA) process. MOPPB [ β = 1.68 × 10 –5 m/W, n 2 = 10.2 × 10 –12 m 2 /W, χ (3) = 3.5 × 10 –9 m 2 /V 2 ] possess higher NLO coefficients than pure PPB [ β = 0.98 × 10 –5 m/W, n 2 = 4.62 × 10 –12 m 2 /W, χ (3) = 6.1 × 10 –9 m 2 /V 2 ] which assured the superiority of azo dye incorporation in PPB crystals. Pristine and MOPPB crystals depict the optical limiting (OL) behavior under continuous wave (CW) diode laser irradiation at 785 nm. Thus, the linear and nonlinear properties bestow the MOPPB single crystal as a versed material for OL devices used for the safeguard of optical components from laser damage.

Chromophores in azo dyes are optically active and play an important role in modifying the optical nonlinear properties. Methyl orange (MO), an azo dye, has been chosen to dope with l‐arginine monohydrochloride (LAHCl), in order to tune the nonlinear optical properties. Pristine and MO doped LAHCl single crystals are grown by slow solvent evaporation method at ambient conditions. The grown crystals are confirmed by powder X‐ray diffraction and Fourier transform infrared studies. The crystals are subjected to linear and nonlinear optical characterizations. Decrease in optical band gap with increase in refractive index and birefringence are attributed to the increase in net macro‐polarizability of the doped LAHCl. Both pristine and MO doped crystals exhibit reverse saturable absorption (RSA) in Z‐scan measurements. The samples show optical limiting behavior under laser irradiation at 650 nm. The chromophore of MO has a significant role in enhancing RSA and optical limiting behavior of LAHCl.

4-Nitrobenzoic acid (4-NBA) single crystals were studied for their linear and nonlinear optical properties. The crystals were grown by slow solvent evaporation method at room temperature. The structure and functional groups were confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic studies. The 4-NBA crystal has an optical absorption at 263 nm and a wide transparency window for the visible light. Theoretical predictions for the measured optical absorption and charge transfer mechanism in 4-NBA were explained with HOMO and LUMO illustrations. The crystal is found to be birefringent and has produced an optical quality interference pattern. The optic plane of the crystal is observed along \(\langle 1 0 0\rangle \) direction. The crystal exhibits nonlinear optical effects viz. reverse saturable absorption and self-defocussing of laser beam. Considerable nonlinear refraction \((n_{2})\) and nonlinear absorption (\(\beta \)) coefficients and third-order nonlinear optical susceptibility \((\chi ^{(3)})\) were determined using Z-scan technique.

L-arginine hydrochloride (LAHCI) solutions of 1 M (A) and 2M (B) concentrations have been investigated for optical nonlinearity under a continuous wave (CW) diode laser of wavelength 670nm. Nonlinear absorption (beta), nonlinear refraction (n(2)) and third-order nonlinear optical susceptibility (x((3))) of LAHCI solutions (A and B) have been measured. Excited state absorption (ESA) assisted reverse saturable absorption (RSA) has been observed to be the reason for nonlinearity in the material. The nonlinear absorption has been observed to increase with increase in concentration of the solution. Thermal aberration rings have been formed by tightly focused Gaussian laser beam and also the beam suffered a self-phase modulation. The observed RSA has been effectively used to verify the optical limiting behaviour of LAHCI solutions. Theoretically predicted third-order nonlinear polarizability has a negative value that further conform the self-defocusing behaviour of LAHCI. (C) 2018 Elsevier GmbH. All rights reserved.