Second-harmonic generation in dry powders: A simple experimental method to determine nonlinear efficiencies under strong light scattering

Aramburu, I.; Ortega, J.; Folcia, C. L.; Etxebarría, J.

doi:10.1063/1.4866160

Cited by 38 publications

(37 citation statements)

References 20 publications

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“…The value of the diagonal effective hyperpolarizability of OHP‐CBS crystals is of the same order of magnitude as that of state‐of‐the‐art electro‐optic salt crystals, e.g.,

β_{iii}^{eff}

= 155 × 10 −30 and 161 × 10 −30 esu for HMQ‐T and DAST crystals, respectively . To confirm the reliability of the obtained values, a quantitative powder second harmonic generation (SHG) test of OHP‐CBS and DAST crystalline powders is performed as a function of the fundamental pump wavelength (see Figure e). Because SHG intensity is proportional to the square of the number density N and spatially averaged square of the effective hyperpolarizabilities ( N 2 <(

β_{}^{eff}

) 2 >), we plot the square root of the relative SHG intensity (( I OHP‐CBS / I DAST ) 0.5 ) in Figure e to qualitatively represent the ratio of effective second‐order nonlinear optical susceptibilities.…”

Section: Resultsmentioning

confidence: 80%

Yellow‐Colored Electro‐Optic Crystals as Intense Terahertz Wave Sources

Jeong

Kang

Lee

et al. 2018

Adv Funct Materials

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This study presents newly developed yellow-colored organic electro-optic crystals to provide high terahertz (THz) wave generation efficiency. Compared with currently existing red-or orange-colored electro-optic crystals, which are used for most benchmark organic THz sources, yellow-colored crystals have additional superior advantages for THz wave generation, e.g., higher transparency in the visible wavelength range with accompanying different phase-matching possibilities. The new yellow-colored crystals consist of a highly nonlinear optical 4-(4-hydroxystyryl)-1-methylpyridinium (OHP) cation, with a relatively short wavelength of maximal absorption at 390 nm in solution, and various halogen-substituted benzenesulfonate anions, with strong secondary-bonding ability. OHP 4-chlorobenzenesulfonate (OHP-CBS) crystals exhibit large off-resonant macroscopic optical nonlinearity and high transparency, with a cut-off wavelength for solid-state absorption near 490 nm. OHP-CBS crystals provide excellent THz wave generation characteristics based on optical rectification. A 0.53 mm thick OHP-CBS crystal delivers ≈27 times higher optical-to-THz conversion efficiency and a much broader spectrum bandwidth compared with the standard 1.0 mm thick ZnTe at 1300 nm pumping. Particularly, compared with a benchmark organic quinolinium crystal with a similar thickness of 0.55 mm, OHP-CBS crystals exhibit 1.7 times higher optical-to-THz conversion efficiency, and show a significantly different THz spectral shape.

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“…The value of the diagonal effective hyperpolarizability of OHP‐CBS crystals is of the same order of magnitude as that of state‐of‐the‐art electro‐optic salt crystals, e.g.,

β_{iii}^{eff}

β_{}^{eff}

Section: Resultsmentioning

confidence: 80%

Yellow‐Colored Electro‐Optic Crystals as Intense Terahertz Wave Sources

Jeong

Kang

Lee

et al. 2018

Adv Funct Materials

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“…The isomorphic PFB‐based crystals exhibit a large macroscopic nonlinear optical response that is important for applications. In semiquantitative powder second harmonic generation (SHG) measurements,23–25 all PFB‐based crystals exhibit a strong SHG signal, which is comparable (or even higher) to the benchmark 4‐(4‐( N,N ‐dimethylamino)styryl)‐1‐methylpyridinium 4‐methylbenzenesulfonate (DAST) crystals having state‐of‐the‐art nonlinear optical susceptibility26 at the fundamental wavelengths of 1400−1800 nm, as shown in Figure 1c. The square root of the SHG intensity scales with the macroscopic nonlinear optical susceptibility, i.e., with the effective hyperpolarizability

β_{i j k}^{eff}

and the number density N of nonlinear optical chromophores 15.…”

Section: Resultsmentioning

confidence: 94%

X‐Shaped Alignment of Chromophores: Potential Alternative for Efficient Organic Terahertz Generators

Lee

Kim

Jazbinšek

et al. 2020

Advanced Optical Materials

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Efficient broadband organic terahertz (THz) generators using X‐shaped alignment of the nonlinear optical chromophores, as an alternative to the parallel alignment of chromophores in benchmark organic crystals, are reported. All the developed six organic benzothiazolium crystals exhibit an isomorphic X‐shaped alignment of chromophores, resulting in an unprecedentedly large off‐diagonal optical nonlinearity (>100 × 10−30 esu), which presents one of the largest off‐diagonal optical nonlinearity of organic crystals. The benzothiazolium crystals exhibit efficient broadband THz wave generation employing the off‐diagonal optical nonlinearity, in contrast to the present state‐of‐the‐art organic THz generators that mostly utilize diagonal optical nonlinearity. For using off‐diagonal and diagonal optical nonlinearities, the polarization of the optical pump is perpendicular and parallel, respectively, to the polar axis of crystals. In addition to a large THz wave generation efficiency with one order of magnitude higher peak‐to‐peak THz electric field than that generated in a 1.0‐mm‐thick inorganic benchmark ZnTe crystal, the benzothiazolium crystals generate broadband THz spectra with an upper cut‐off frequency of near 8 THz, and the absence of strong absorption dimples in the range of 0.5−4 THz. Therefore, the X‐shaped alignment of chromophores presents an interesting potential alternative for efficient broadband organic THz generators.

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“…The maximal SHG signal is found for particle size r~ l C and odd multiples of l C . This model does not take into account many other parameters, e.g., the scattering of the crystalline particles of the sample, and has recently been revisited by Aramburu et al [28] from a theoretical point of view, but also from an experimental viewpoint as, e.g., sample preparation and detection geometry [29,30]. 2).…”

Section: Phase-matching Properties In a Randommentioning

confidence: 99%

“…As mentioned above, for quantitative responses in view of obtaining valuable data on the nonlinear optical coefficients of the material studied, the reader can refer to recent works from Aramburu et al [28][29][30].…”

Section: Sample Preparation and Calibrationmentioning

confidence: 99%

Relevance of the Second Harmonic Generation to Characterize Crystalline Samples

et al. 2015

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The application of powder second harmonic generation (P-SHG), temperatureresolved SHG (TR-SHG), and SHG microscopy (SHGM) in the characterization of bulk crystalline samples is illustrated. P-SHG applied to powder samples can be an extremely sensitive approach to detect the absence of an inversion center in crystalline structures, TR-SHG serves to monitor temperature-induced phase transitions, and SHGM is used in the detection of non-centrosymmetric zones inside a heterogeneous material. These methods are of great relevance, e.g., in the pharmaceutical industry where crystalline active pharmaceutical ingredients are often made of a single enantiomer and are therefore non-centrosymmetric. Herein, several examples are provided to describe how a given SHG signal should be interpreted. A general procedure to carry out a P-SHG experiment is illustrated in detail.

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Second-harmonic generation in dry powders: A simple experimental method to determine nonlinear efficiencies under strong light scattering

Cited by 38 publications

References 20 publications

Yellow‐Colored Electro‐Optic Crystals as Intense Terahertz Wave Sources

Yellow‐Colored Electro‐Optic Crystals as Intense Terahertz Wave Sources

X‐Shaped Alignment of Chromophores: Potential Alternative for Efficient Organic Terahertz Generators

Relevance of the Second Harmonic Generation to Characterize Crystalline Samples

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