Photosensitive Hybrid Materials Research Articles

Ag nanoparticle-doped SiO2/TiO2 hybrid optical sensitive thin film for optical element applications

Abstract The optical sensitive thin film by Ag nanoparticles doped SiO2/TiO2 hybrid was successfully deposited via sol-gel spin coating technique. Photo-induced polymerization of photosensitive Ag-doped SiO2/TiO2 hybrid initiated by irgacure 784 photoinitiator was illustrated under visible region by He Cd laser 442 nm. Silane coupling was used as a starting precursor to providing cross-linking in the photochemical reaction process. The structural properties and existing elements of photosensitive films were characterized by XRD, TEM and EDX. Meanwhile, surface morphology of the photosensitive hybrid films was monitored by FE-SEM. Moreover, the optical absorption of the photosensitive hybrid films was analyzed by UV–Vis spectroscopy. These results indicated that the compatibility of photosensitive hybrid material was formed. The SiO2/TiO2 photosensitive hybrid films with uniformly distributed Ag ions and intensive coloration characteristic for surface plasmon resonance phenomena relating to the enhancement of optical absorption in visible region. As-prepared photosensitive hybrid films with enhanced optical properties can be proposed for optical elements.

Fabrication of ridge waveguide structure from photosensitive TiO2/ormosil hybrid films by using an ultraviolet soft imprint technique

Photosensitive TiO2/organically modified silane hybrid films were prepared by combining a low-temperature sol–gel process with a spin-coating technique. Optical properties and photochemical activities of the as-prepared hybrid sol–gel films under different UV irradiation time were characterized and monitored by prism coupling technique, UV–visible spectroscopy, and Fourier transform infrared spectroscopy. Surface morphology of the hybrid films was also observed by an atomic force microscopy. Advantages for fabrication of ridge waveguide structure based on the photosensitive hybrid films were demonstrated by an ultraviolet soft imprint technique. Effects of imprint force, imprint time, and UV irradiation time on high replication fidelity of the ridge waveguide structure were also investigated. An altitude replication fidelity of 99.7% can be obtained when the imprint force of 2MPa, imprint time of 30min and UV irradiation time of 45min were chosen. Scanning electron microscopy and surface profiler were used to characterize the morphological and surface profile properties of the as fabricated ridge waveguide structure. Results indicate that the as-prepared photosensitive hybrid materials have great applicability for the fabrication of micro-optical elements and advantage as the imprint layer under the ultraviolet soft imprint technique.

3D microoptical elements formed in a photostructurable germanium silicate by direct laser writing

We present our investigations into the fabrication of three-dimensional microoptical elements by the direct femtosecond laser writing of a germanium–silicon photosensitive hybrid material. Germanium glass composites are very interesting for optical applications as they are photosensitive, and maintain high optical transparency in the visible and near-infrared bands of the spectrum. Here, we have used a germanium containing hybrid material to make nanophotonic structures and microoptical elements such as photonic crystal templates, prisms and spatial polarization plates, both on flat surfaces and fiber tips. Our results show that this germanium silicate composite is an excellent material for microoptics fabrication.

Fabrication of micro-lens arrays built in photosensitive hybrid films by UV-cured imprinting technique

Photosensitive TiO2-contained organic–inorganic hybrid films were prepared by combining a low-temperature sol–gel process with a spin-coating technique. Optical properties and photochemical activities of the as-prepared hybrid sol–gel films were characterized by prism coupling technique, thermal gravimetric analysis, UV–Visible spectroscopy, and Fourier transform infrared spectroscopy. Advantages for fabrication of micro-lens arrays based on the as-prepared photosensitive hybrid films were demonstrated by a direct-contact lithography technique and a reflow technique, followed by an UV-cured imprinting technique. Results indicate that the as-prepared photosensitive hybrid materials have great applicability for the fabrication of photonic components. Micro-sphere lens arrays and micro-ellipsoid lens arrays with the diameter from 20 to 100 μm and built in the as-prepared hybrid films were obtained. Morphological and surface profile properties of the as-fabricated micro-lens arrays were characterized by scanning electron microscopy and surface profiler, respectively. Results indicate that the fabrication process of the micro-lens arrays is a simple, cost-effective and mass production process, and the as-prepared photosensitive hybrid materials have great potential applications for the fabrication of the micro-optical elements.

New photosensitive colorless polyimide-silica hybrid optical materials: Synthesis, properties and patterning

We report the synthesis, properties, and patterning of non-fluorinated photosensitive polyimide-silica hybrid optical materials. End-functionalized ionic salt photosensitive poly(1,4-bis(3,4-dicarboxyphenoxy)-2,5-ditertbutylbenzene-dianhydride-co-oxydianiline) (DDBBDA-ODA)/2-methylacrylic acid 2-dimethylamino ethyl ester (MDAE) was prepared first. It was then reacted with tetramethoxysilane (TMOS)-derived silica sol and 3-methacryloxypropyl trimethoxysilane (MSMA) to obtain the ultralow volume shrinkage hybrid optical materials. The experimental results showed the nano-silica domain and the crosslinked structures significantly enhanced the thermal properties, such as the glass transition temperature and coefficient of thermal expansion. The prepared hybrid film not only exhibited high transparency in the visible region but also had tunable refractive index, low birefringence and optical loss by introducing the silica moiety. The SEM image suggested the prepared photosensitive hybrid materials could obtain fine lithographical patterns with an excellent dimensional stability. The combination of excellent optical properties and dimensional stability suggested the potential applications of the prepared hybrid materials for optoelectronic device applications.

Synthesis and optical properties of photosensitive polyimide/silica hybrid thin films

In this study, the photopatternable fluorinated polyimide/silica hybrid materials were synthesized by 4,4′-hexafluoroisopropylidenediphthalic anhydride (6FDA), oxydianiline (ODA), aminopropyltriethoxysilane (APrTEOS), and 12 nm colloidal silica with a coupling agent. The monodispersed colloidal silica was used to form a silica domain instead of alkoxysilanes in the conventional process. The coupling agents used were 3-methacryloxypropyl trimethoxysilane (MPTMS) or (4-vinylphenethyl)trimethoxysilane (VPTMS). The coupling agent and the silica domain were designed to reduce the volume shrinkage and enhance the thermal properties, respectively. The retention of 2-methyl acrylic acid 2-dimethylamino-ethyl ester (MDAE) in the prepared hybrid films was supported by X-ray photoelectron spectroscopy (XPS) and thickness variation during the curing process. The particle size of silica in the hybrid materials based on SEM analysis was in the range of 10–25 nm. The prepared hybrid materials also exhibited a reduced refractive index after increasing the silica content. The SEM diagram suggested the prepared photosensitive hybrid materials could obtain lithographical patterns with a good resolution. These results indicate that the newly prepared photosensitive polyimide/silica hybrid materials may have potential applications for optical devices.

Preparation and Patterning of Optical Hybrid Thin Films Based on Photosensitive Polyimide and Monodispersed Colloidal Silica

In this study, optical hybrid thin films were prepared from photosensitive poly(4,4-(hexafluoroisopropyl- idenediphthalic anhydride)-co-oxydianiline) (6FDA-ODA)/MDAE and monodispersed colloidal silica with a coupling agent. It was a combination of the sol–gel reaction, thermal polymerization and spin coating. The coupling agents were 3-methacryloxypropyl trimethoxysilane (MPTMS) or (4-vinylphenethyl)trimethoxysilane (VPTMS). The silica content in the hybrid thin films was varied from 0 to 8.6wt%. The coupling agent and the silica domain were designed primarily for reducing the volume shrinkage and enhancing the thermal properties, respectively. The retention of MDAE in the prepared hybrid films is supported by X-ray photoelectron spectroscopy (XPS). The silica domain significantly enhanced the thermal properties of the prepared hybrid films in comparison with parent fluorinated polyimide. The prepared hybrid materials also exhibited reduced refractive index by increasing the silica content. The results of SEM showed the prepared photosensitive hybrid materials could obtain lithographical patterns with a good resolution. These results indicated that the newly prepared photosensitive polyimide/colloidal silica hybrid thin films had potential applications for optical devices.

Direct pattern of photocurable glycidoxypropyltrimethoxysilane based sol–gel hybrid waveguides for photonic applications

We report on a photosensitive hybrid material based on 3-glycidoxypropyltrimethoxysilane (GPTMS) and on the cationic photopolymerization of the epoxide groups. In particular, we describe the synthesis and fabrication of patterned waveguide structures by ultraviolet (UV) irradiation through a quartz slide with a metallic mask. An increase of 0.01 of the material refractive index has been measured when the film is exposed to UV light in the range of 220–260 nm. The surface morphology and the optical properties of the structures are reported.

Photocurable glycidoxypropyltrimethoxysilane based sol-gel hybrid materials

Abstract Hybrid sol-gel materials are promising candidates for electro/optical applications, combining the most important glass-like and polymer-like properties. Hybrid patternable materials produced by photopolymerisation processes have been mainly developed on 3-methacrloxypropyltrimethoxysilane based systems in which the polymerisable organic function is the C C bond of the methacrylic group. A new photosensitive hybrid material is described here, based on 3-glycidoxypropyltrimethoxysilane (GPTMS) and on the cationic photopolymerisation of the epoxide groups, which lead to the formation of a PEO organic interpenetrating network.

Photosensitive polyimide/silica hybrid optical materials: Synthesis, properties, and patterning

In conventional ionic salt photosensitive polyimides, large volume shrinkage during imidization would be occurred due to eliminating pendant photosensitive moieties, such as 2-methyl acrylic acid 2-dimethylamino-ethyl ester (MDAE). In this study, the volume shrinkage of photosensitive poly(4,4′-(hexafluoroisopropylidenediphthalic anhydride)- co-oxydianiline) (6FDA-ODA)/MDAE was largely reduced by photocrosslinking MDAE with a coupling agent and the silica domain in the hybrid materials. The used coupling agents were 3-methacryloxypropyl trimethoxysilane (MPTMS) or (4-vinylphenethyl)trimethoxysilane (VPTMS). The coupling agent and the silica domain are designed primarily for reducing the volume shrinkage and enhancing the thermal properties, respectively. The retention of MDAE in the prepared hybrid films is supported by X-ray photoelectron spectroscopy (XPS) and thickness variation during curing process. The silica domain in the hybrid materials from TEM analysis was in the range of 10–50 nm, which was formed by the coupling agent and tetramethoxysilane. The silica domain significantly enhanced the thermal properties of the prepared hybrid films in comparison with parent fluorinated polyimide, including the glass transition temperature and coefficient of thermal expansion. The prepared hybrid materials also exhibited reduced refractive index and optical loss by increasing the silica. The SEM diagram suggested the prepared photosensitive hybrid materials could obtain lithographical patterns with a good resolution. These results indicate that the newly prepared photosensitive polyimide/silica hybrid materials may have potential applications for optical devices.

High Photosensitive Sol-Gel Hybrid Materials for Direct Photo-Imprinting of Micro-Optics

Sol-gel derived inorganic-organic hybrid materials (HYBRIMERs) were found to have high photosensitivity arising from large changes in refractive index and volume upon exposure to light. These materials combined different photosensitive mechanisms due to the presence of polymers and silica in the HYBRIMER structure. Photo-induced densification of a germanium-doped HYBRIMER gave an increase in refractive index accompanying a volume contraction. A methacrylate HYBRIMER was decomposed by long UV illumination, giving a low refractive index and resulting in a reduction in film thickness. Also, photo-initiators were locked inside the methacrylate HYBRIMER during illumination, giving a simultaneous increase in the refractive index and film thickness. Direct photo-imprinting using the photosensitive HYBRIMER was demonstrated for simple fabrication of gratings, microlens, and waveguides using a photomask, a phase mask, an interferometer, and laser writing.

Photoinduced Low Refractive Index Patterning in a Photosensitive Hybrid Material

AbstractLight illumination processing created photoinduced reduction of refractive index as well as volume contraction in an organic-inorganic hybrid material. Whereas both refractive index and film thickness are decreased significantly by the light exposure, transmittance and anti-soiling property of the hybrid film are not affected by the exposure. Direct patterning is possible upon light illumination using the photoinduced change in thickness without any developing process.