The linear and nonlinear optical properties of the organic nonlinear material 4-nitro-4′-methylbenzylidene aniline

Abstract

The organic crystal 4-nitro-4′-methylbenzylidene aniline (NMBA) was identified as a promising nonlinear material by the powder technique. The material gave a second harmonic intensity 16 times that of urea. Large single crystals of dimensions 5×3×1 cm3 were grown by the temperature lowering of a seeded supersaturated ethyl acetate solution. The principal dielectric axes were defined by orthoscopic examination. The dispersions of the refractive indices were determined to an accuracy of ±0.0015 using the minimum deviation technique and Maker fringe spacings. These dispersion curves were fitted to a Sellmeier equation which allowed the indices to be determined to ±0.0006. The nonlinear d coefficients d11, d33, d31, and d13 were evaluated at 1000, 1064, and 1300 nm using the Maker fringe technique. The coefficient d11 was over 200 times larger than potassium dihydrogen phosphate (KDP) d36. In addition, the nondiagonal coefficient d31 was similar to the phase-matching coefficient in the organic material 3-acetamido-4-dimethylamino-nitrobenzene (DAN). Critically phase-matched second harmonic signals were observed at all fundamental wavelengths. There was excellent agreement between the experimentally determined and theoretical phase-matched incidence angles. Noncritical phase-matched conditions have been calculated and are reported. Both angle and wavelength noncritical phase matching is possible with this crystal.

Probing microporous materials with second-harmonic generation

“…For MOFs mostly only preliminary Kurtz powder results have been reported, which consist of reporting the SHG-intensity of the MOF powder with respect to a SHG-intensity of a reference. Even when the phase matching conditions and, depending on the type of phase matching, the particle size and coherence length of the sample and reference are taken into account, this method still provides values that can differ an order of magnitude from those obtained in accurate single crystal SHG-measurements [50][51][52]. So ideally Maker fringe measurements on single crystals [51,53] or oriented thin films [9,53,54] are used, which have the added value of also being able to determine the relative values of the different second-order tensor components v ijk (2) .…”

Growth and characterization of a new organic nonlinear optical crystal: 1-(3-Nitrophenyl)-5-phenylpenta-2,4-dien-1-one

“…The conjugated π-electron moiety provides a pathway for the entire length of conjugation under the perturbation of an external electric field. Fictionalization of both ends of the π-bond systems with appropriate electron donor and acceptor group can increase the asymmetric electronic distribution in either or both the ground and excited states, thus leading to an increased optical nonlinearity [4][5][6][7].…”

Electrical and Optical Nonlinearity in Vacuum-Deposited Thin Films of Poly[n-(4-Benzoylphenyl)-2-Methylacrylamide]

“…[9][10][11][12][13][14] But with improved understanding of the underlying molecular properties, it has been found that the performance of these organic materials could exceed that of currently-used inorganic materials by several orders of magnitude. [15][16][17][18][19][20] These organic materials offer versatility and ease of modification and generally exhibit nonlinear properties, which far surpass those of commercially available inorganic materials. To be considered as an active nonlinear material, it must have an exceptionally large nonlinear susceptibility.…”

“…2 The nonlinear susceptibility of these organic materials arise due to their molecular electronic properties. [2][3][4][15][16][17][18] This can be achieved by preparing materials with attached side chains, which can be manipulated and modified during chemical synthesis. These side chains are flexible enough at higher temperatures.…”

“…These side chains are flexible enough at higher temperatures. [15][16][17] Another requisite for a nonlinear organic material is that its structure must be noncentrosymmetric for the second order phenomena. The polymer may be used in a number of different macroscopic forms: crystal, polymer, thin film etc.…”