Highly Efficient Organic/Inorganic Hybrid Nonlinear Optic Materials via Sol−Gel Process:  Synthesis, Optical Properties, and Photobleaching for Channel Waveguides

Abstract

The thermally stable second-order nonlinear optic (NLO) hybrid materials were successfully prepared by a sol-gel process using dye-attached sol-gel monomers (ormosils) of difunctionalized or trifunctionalized second-order NLO chromophores attached to silicon atoms. The dye-attached sol-gel monomers were synthesized by the coupling reaction of 3-isocyanatopropyltriethoxysilane with the corresponding functionalized NLO chromophores in DMAc. The dye-attached sol-gel monomers were homopolymerized and copolymerized with TEOS by hydrolysis and polycondensation in the presence of a slight excess amount of acidified water (pH 3), yielding the hybrid precusors (or a homogeneous solution). The hybrid precursors were spin-coated on various substrates such as ITO glass and NaCl disk. Hybrid films were further polycondensed by curing at 170°C for 3 h. The cured hybrid materials existed in monohydroxy (T 2 , Q 3 ) and nonhydroxy (T 3 , Q 4 ) states, indicating the formation of a highly cross-linked silicon-oxygen polymeric network. All of the cured organic/SiO 2 hybrid films are transparent. The organic/SiO 2 hybrid materials were quite stable at elevated temperatures above 250°C. The hybrid films were poled by corona discharge technique or dc contact electrode. The values of electro-optic coefficient for the organic/SiO 2 hybrid materials were in the range of 3.7 to 16 pm/V at the wavelength of 1.3 µm, depending on dye-attached sol-gel monomers and poling conditions. The SG-DANS (1:2:2) film shows excellent temporal stability. The r 33 signal remained at 80% of its initial value after heating even at 150°C for 3 h. Also, the second-order nonlinear optical coefficient d 31 of 72 pm/V for the SG-DANS (1:2:0) hybrid film measured by the Maker fringe technique was obtained. The refractive index was decreased after photobleaching. Using the hybrid film, a singlemode channel waveguide was also fabricated by the photobleaching method. The mode pattern confirmed that a channel waveguide was single-mode, and the optical propagation loss was measured to be less than 1 dB/cm.

Organic-inorganic electronics

“…Nonlinear, optically active (NLO) organic dye molecules may also be oriented within silicate networks by applying an electric field (known as "poling"). Confining the molecules in the inorganic framework improves the nonlinear optical response of the composite, since the inorganic framework restricts the motion of the organic molecules and prevents randomization of molecular orientation due to thermal relaxation [15][16][17][18]. The restrictive environment of the silicate network is also useful as a matrix for organic LED and solid-state laser materials.…”

Progress in Sol-Gel Technology for the Coatings of Fabrics

“…In 1981, the first international workshop on glasses [77,79,81,87] and ceramics from gels was held, which helped to further develop sol-gel technology. Sol-gel technology is being used widely since 1980 in the process of synthesizing superconducting materials [88], functional ceramic materials [89], nonlinear optical materials [90], catalysts and enzyme carriers…”

Fluorescent Dyes Used in Polymer Carriers as Imaging Agents in Anticancer Therapy

“…All SiNPs have approximately the same size and composition but selected dyes (e.g., fluorescein, pyrene) [374,375] might exhibit different photophysical properties [376]. The silica matrix provides embedded dyes an effective barrier to protect them against the surrounding environment and both photobleaching and photodegradation phenomena can be minimized [377]. Van Blaaderen et al [372] used also direct coupling of FITC dye molecules to the silane reagent (3-aminopropyl)triethoxysilane (APTS) by a covalent bonding to incorporate chromophore into the silica matrix.…”