Strong second-harmonic generation from centrosymmetric dyes

Ashwell, Geoffrey J.; Jefferies, Gary; Hamilton, Darren G.; Lynch, Daniel Ε.; Roberts, M. P. S.; Bahra, Gurmit S.; Brown, Charles R.

doi:10.1038/375385a0

Cited by 204 publications

(104 citation statements)

References 17 publications

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“…The magnitude of the effect observed by Ashwell et al [1,2] is much larger than the SHG output from thin films of other centrosymmetric molecules such as copper phthalocyanine [3] and C 60 . [4] All expressions for the electric dipole mechanism [5,6] for doubling the frequency of incident light (i.e., SHG) involve a triple product of matrix elements of electric dipole operators.…”

Section: Introductionmentioning

confidence: 81%

“…Ashwell et al [1,2] recently reported that squaraine molecules, which are centrosymmetric in the crystalline state, can exhibit second-harmonic generation (SHG) when deposited as Langmuir±Blodgett (LB) monolayer films, and the occurrence of non-centrosymmetric ensembles with concomitant intermolecular charge transfer has been proposed as the cause of these unexpected results. The magnitude of the effect observed by Ashwell et al [1,2] is much larger than the SHG output from thin films of other centrosymmetric molecules such as copper phthalocyanine [3] and C 60 .…”

Section: Introductionmentioning

confidence: 99%

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A Mechanism for Strong SHG by Centrosymmetric Anilinosquaraine Dyes

Honeybourne¹

1999

Adv. Mater.

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Aggregation of centrosymmetric squaraines into acentric dimers, followed by intermolecular charge transfer (CT) between the centric monomers of the dimer, has been proposed in the past as the mechanism by which these molecules exhibit surprisingly high SHG when deposited as Langmuir–Blodgett monolayer films. Here an alternative mechanism is considered, in which the center of symmetry is destroyed by distortion of the charge distribution in one molecule by the highly polar molecular environment of its nearest neighbors, so that the large potential contributions from intramolecular CT to SHG become symmetry allowed.

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Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

A Mechanism for Strong SHG by Centrosymmetric Anilinosquaraine Dyes

Honeybourne¹

1999

Adv. Mater.

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“…Other studies have been undertaken that just concentrate on the large two-photon absorption cross-sections that pyrrolyl squaraine dyes exhibit [32,33,52,55,66]. Following the discovery that symmetrical bis(anilino)squaraine dyes exhibit second-order nonlinear optical effects as Langmuir-Blodget deposited monolayers on hydrophilic glass slides [93], results for a range of pyrrolyl squaraines were similarly reported [11,13,14]. Latter second-order non-linear optical studies on pyrrolyl squaraines have employed electric-field induced second harmonic generation (EFISH) measurements, although these measurements can only be taken on unsymmetrical pyrrolyl squaraine dyes [39].…”

Section: Optical Propertiesmentioning

confidence: 99%

Pyrrolyl Squaraines–Fifty Golden Years

Lynch

2015

Metals

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Pyrrolyl squaraines, both dyes and polymers, were first reported in 1965 and since then a fascinating body of work has been produced investigating the chemistry of these interesting molecules. A major aspect of these molecules that makes them so appealing to those researchers who have contributed to this field over the last 50 years is their chemical versatility. In this review, subjects, such as the synthetic history, an understanding of the molecular structure, an overview of the optical properties, a discussion of both the electrical conduction properties, and magnetic properties, plus use of the particles of pyrrolyl squaraines, are presented. Furthermore, previously published results are not just presented; they are in certain cases collated and used to both highlight and explain important aspects of pyrrolyl squaraine chemistry.

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“…Even though the material belongs to centrosymmetric it exhibits SHG activity due to intermolecular hydrogen bonding and charge transfer interactions between the donor and acceptor systems. The SHG in BSL crystal is due to weak interaction between the dipoles, which is easy for the ground state to turn into the excited state as a charge separated form and generate the stable asymmetrical distribution of electron cloud density thus exhibiting a minimum SHG effect [40,41]. The SHG efficiency of BSL crystal is compared with other reported SHG efficiencies of centrosymmetric materials and is tabulated in Table 3.…”

Section: Vickers Microhardness Analysismentioning

confidence: 99%

Growth and Characterization of Benzimidazolium Salicylate: NLO Property from a Centrosymmetric Crystal

Amudha

Rajkumar

Thayanithi

et al. 2015

Advances in Optical Technologies

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A new organic charge transfer molecular complex salt of benzimidazolium salicylate (BSL) single crystals was grown by the slow evaporation solution growth technique using methanol as a solvent at room temperature. The grown crystals were characterised by single crystal X-ray diffraction (XRD) which confirms that the crystal belongs to monoclinic system with the centrosymmetric space group P2 1 / . The crystalline perfection of the grown crystal was analyzed by high resolution X-ray diffraction (HRXRD). The presence of various functional groups was identified by FTIR spectrum. UV-Vis spectral study reveals that the BSL crystal is optically transparent in the wavelength region 342 nm-1100 nm. Dielectric measurements of the crystal at various frequencies were also determined. The mechanical properties of the grown crystal were assessed using Vickers microhardness testing. Nonlinear optical property of the crystal was confirmed using Kurtz and Perry powder technique and the SHG efficiency of the BSL crystal is 0.7 times greater than that of the standard KDP crystal.

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Strong second-harmonic generation from centrosymmetric dyes

Cited by 204 publications

References 17 publications

A Mechanism for Strong SHG by Centrosymmetric Anilinosquaraine Dyes

A Mechanism for Strong SHG by Centrosymmetric Anilinosquaraine Dyes

Pyrrolyl Squaraines–Fifty Golden Years

Growth and Characterization of Benzimidazolium Salicylate: NLO Property from a Centrosymmetric Crystal

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