Recent developments of molecular architectural control and solid-state engineering have led to exceptionally large electro-optic (EO) activities in organic and polymeric nonlinear optical (NLO) materials. A new generation of NLO dendrimers has been developed to generate well-defined nano-objects, minimize strong intermolecular electrostatic interactions, and improve poling efficiency and stability. A facile and reliable Diels-Alder "click" reaction was applied for lattice hardening to improve physical properties of cross-linkable EO polymers. The "click" chemistry also provides means to study the relationship between EO activity, chromophore shape, and number density of the chromophore, systematically. The NLO dendrimers or polymers were used as hosts for guest chromophores to increase chromophore concentration and improve poling efficiency. A variety of nanostructured organic and polymeric materials with ultrahigh r 33 values (>350 pm/V at the wavelength of 1310 nm, more than 10 times that of LiNbO 3 ) and excellent temporal alignment stability at 85 °C were achieved by the approaches.

We demonstrate a near-infrared electro-optic modulator with a bandwidth of 3 GHz and a V(pi)L figure of merit of 0.8 V-cm using a push-pull configuration. This is the highest operating speed achieved in a silicon-polymer hybrid system to date by several orders of magnitude. The modulator was fabricated from a silicon strip-loaded slot waveguide and clad in a nonlinear polymer. In this geometry, the electrodes form parts of the waveguide, and the modulator driving voltage drops across a 200 nm slot.

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Freestanding two-dimensional (2D) few-layer graphene was formed through laser exfoliation of highly ordered pyrolytic graphite, using a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. Graphene sheets of several nanometers in thickness and micrometers in size were obtained. The laser exfoliation process was investigated at different laser fluences and distances between target and substrate. Three different phases, amorphous carbon, few-layer graphene sheets, and thin graphite films, were obtained as the laser fluence increased. This study reveals an existing route of forming freestanding 2D nanostructures through laser exfoliation.

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Recent development of tailored organic electric-optic (OEO) materials and their applications in hybrid device systems has been reviewed. Hybrid systems encompass the optical and/or electrical components that form intimate contact with OEO materials, such as metal oxide barrier layers, solution processable passive waveguides, silicon nanoslots, and photonic CMOS chips, etc. These systems offer unique advantages combining excellent properties and simple processing for advanced photonic device platforms. Examples include the demonstration of low-V π and low-loss EO modulators in hybrid polymer sol-gel waveguides, CMOS-compatible hybrid polymer/silicon slotted waveguides, and EO polymer-clad silicon nitride ring resonator modulators. This review also provides a future prospect for the development of OEO materials and their hybrid systems.

A series of cross-linkable electro-optic (E-O) dendrimers have been developed with anthracene- and acrylate-containing dendrons functionalized on the periphery of chromophores that can form thermally stable Diels−Alder adducts. These new E-O dendrimers with a high density of standardized AJL8-type chromophore are originally prone to thermo-decomposition in their thermoplastic form but can be converted into thermally stable networks to provide excellent site isolation for these chromophores. After poling, large E-O coefficients (up to 84 pm/V at 1310 nm) can be obtained in these dendrimers. These poled E-O dendrimers can maintain their alignment stability at 200 °C for 30 min and also possess impressive long-term stability at 150 °C for more than 200 h. This result provides a very effective molecular engineering approach to systematically increase the thermal stability of highly polarizable dipolar chromophores for high temperature on-chip applications.

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