New Y type chromophores were synthesized and the hyperpolarizability can be effectively translated into large electro-optic coefficients in poled polymers.

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In this brief review, nonlinear optical (NLO) chromophores widely used in electro-optic (EO) devices are summarized according to their EO coefficients. The advances of EO modulators based on organic materials in high bandwidth and low half wave voltages (V p ) are discussed. The review is mainly devoted to the following aspects: (1) verification of high frequency operation and reduction of V p for all polymer waveguide EO modulators; (2) structures and advantages of sol-gel waveguide EO modulators; (3) principles and developments of silicon-organic hybrid (SOH) EO modulators. All the considerations are illustrated by the architecture of the devices and the used physical and chemical principles are explained in detail. Further means of improvement of their parameters are indicated.

A new diene-conjugated chromophore WJ1 was synthesized with high yield of 36% through an H-bonding induced Vilsmeier reaction. By simple guest-host doping, a large electro-optic efficiency of 337 pm V(-1) at 1310 nm and excellent temporal stability at 75 °C have been achieved in poled films of WJ1/APC with a high loading density of 40 wt%.

Clustering, a traditional machine learning method, plays a significant role in data analysis. Most clustering algorithms depend on a predetermined exact number of clusters, whereas, in practice, clusters are usually unpredictable. Although the Elbow method is one of the most commonly used methods to discriminate the optimal cluster number, the discriminant of the number of clusters depends on the manual identification of the elbow points on the visualization curve. Thus, experienced analysts cannot clearly identify the elbow point from the plotted curve when the plotted curve is fairly smooth. To solve this problem, a new elbow point discriminant method is proposed to yield a statistical metric that estimates an optimal cluster number when clustering on a dataset. First, the average degree of distortion obtained by the Elbow method is normalized to the range of 0 to 10. Second, the normalized results are used to calculate the cosine of intersection angles between elbow points. Third, this calculated cosine of intersection angles and the arccosine theorem are used to compute the intersection angles between elbow points. Finally, the index of the above-computed minimal intersection angles between elbow points is used as the estimated potential optimal cluster number. The experimental results based on simulated datasets and a well-known public dataset (Iris Dataset) demonstrated that the estimated optimal cluster number obtained by our newly proposed method is better than the widely used Silhouette method.

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The synthesis and characterization of new push-pull chromophores A and B, from tricyanofuran (TCF) electron withdrawing and various electron donating moieties, have been demonstrated to compare the roles of donors in electro-optic performance. The crystal structure analyses of the intramolecular hydrogen bond, molecular coplanarity and p-p interactions reveal that A forms crossstacking, while B forms antiparallel dimer packing, which indicates weaker intermolecular interactions of A than B. Also, the photophysical properties, solvatochromic behavior and Density Functional Theory (DFT) calculations were also investigated. In electro-optic activities, the doped films-A containing chromophore A display an r 33 value of 36 pm V 21 at the saturated doping concentration of 40 wt%, while the doped films-B containing B show a maximum r 33 value of 16 pm V 21 at the saturated concentration of 25 wt%. High loading density and high r 33 value indicate that the chromophore A with julolidinyl-based donor can efficiently reduce the interchromophore electrostatic interactions and enhance the macroscopic optical nonlinearity, showing that chromophore A with julolidinyl-based donor has promising applications in nonlinear optical (NLO) materials.