Zuosen Shi

Electro-Optic Modulator Based on Novel Organic-Inorganic Hybrid Nonlinear Optical Materials

A Mach-Zehnder type electro-optic (EO) modulator based on novel organic-inorganic hybrid nonlinear optical materials attached with Disperse Red 19 has been successfully designed and fabricated. The new material system presents a smartly controlled process to overcome the EO effect stability tradeoff of conventional EO polymers and obtains poling efficiency and thermal stability. The characteristic parameters of both the embedded waveguide and the coplanar waveguide traveling-wave electrode are carefully designed and simulated by MATLAB program. The optimized structural properties and fabrication procedures are demonstrated. The electrical-optical overlap factor of fundamental mode is obtained as 85.62%. The device exhibits an EO coefficient of 12.8 pm/V at 1550 nm and stable operation, which shows potential for planar active light-wave circuit applications.

Reconfigurable optical interleaver modules with tunable wavelength transfer matrix function using polymer photonics lightwave circuits

A transparent reconfigurable optical interleaver module composed of cascaded AWGs-based wavelength-channel-selector/interleaver monolithically integrated with multimode interference (MMI) variable optical attenuators (VOAs) and Mach-Zehnder interferometer (MZI) switch arrays was designed and fabricated using polymer photonic lightwave circuits. Highly fluorinated photopolymer and grafting modified organic-inorganic hybrid material were synthesized as the waveguide core and caldding, respectively. Thermo-optic (TO) tunable wavelength transfer matrix (WTM) function of the module can be achieved for optical routing network. The one-chip transmission loss is ~ 6 dB and crosstalk is less than ~25 dB for transverse-magnetic (TM) mode. The crosstalk and extinction ratio of the MMI VOAs were measured as -15.2 dB and 17.5 dB with driving current 8 mA, respectively. The modulation depth of the TO switches is obtained as ~18.2 dB with 2.2 V bias. Proposed novel interleaver module could be well suited for DWDM optical communication systems.

Monolithic multi-functional integration of ROADM modules based on polymer photonic lightwave circuit

A transparent reconfigurable optical add-drop multiplexer (ROADM) module composed of AWG-based wavelength-channel-selectors monolithically integrated with Mach-Zehnder interferometer (MZI) thermo-optic (TO) waveguide switch arrays and arrayed waveguide true-time-delay (TTD) lines is designed and fabricated using polymer photonic lightwave circuit technology. Negative-type fluorinated photoresist and grafting modified organic-inorganic hybrid materials were synthesized as the waveguide core and cladding, respectively. The one-chip transmission loss is ~6 dB and the crosstalk is less than ~30 dB for the transverse-magnetic (TM) mode. The actual maximum modulation depths of different thermo-optic switches are similar, ~15.5 dB with 1.9 V bias. The maximum power consumption of a single switch is less than 10 mW. The delay time basic increments are measured from 140 ps to 20 ps. Proposed novel ROADM is flexible and scalable for the dense wavelength division multiplexing network.

Electric-field-induced layer-by-layer fabrication of inorganic–organic hybrid second-order nonlinear optical films

This work focused on the development of a novel method for molecular level assembly and processing of inorganic-organic hybrid second-order nonlinear optical (SONLO) multilayer films. Aromatic diazo group linked silicon sol was first synthesized and used as a polycation. This oligomer was assembled into inorganic-organic hybrid SONLO multilayer films by electric-field-induced layer-by-layer assembly technique with a low molecular weight chromophore molecule as an anion. After UV irradiation, the electrostatic interaction between layers converted to covalent bonds. Large second-harmonic generation signal of the assembled film was observed, which confirmed that the chromophore in the film had a high degree of molecular orientation as assembled under the electric field. As the cross-linked structure and silicon oxygen meshwork in the films, the resulting inorganic-organic hybrid multilayer films displayed good thermal and chemical stability, and excellent NLO properties.

New anisopleural spindle-like nonlinear optic (NLO) chromophores with a D–D′–π–A′–A or D–A′–π–D′–A structure: interesting optical behavior and DFT calculation results

A new series of anisopleural spindle-like chromophores which have both auxiliary donors and acceptors on their conjugated bridge has been designed and synthesized for the first time. The auxiliary donors and acceptors were introduced close to the donors and acceptors respectively and formed D–D′–π–A′–A structure chromophores termed S-chromophores. The opposite D–A′–π–D′–A structure chromophores are termed F-chromophores. The structure–properties relationship based on these anisopleural spindle-like chromophores has been investigated via1H-NMR, UV-vis characterization and DFT theoretical calculations. S-Chromophores displayed varied chemical shifts of the double-bond proton and a red-shifted maximum absorption wavelength (λmax) as well as a larger absorption intensity (e) compared to the F-chromophores, indicating that the intermolecular charge transfer has been influenced by the structures. Moreover, the red-shifted λmax and larger e indicate a more efficient intermolecular charge transfer which should in turn lead to an increased hyperpolarizability (β) for a given class structure of chromophores. The theoretical calculation β values of the S-chromophores showing an increase further rationalize the experimental results. In this way, the structure–properties relationship has been investigated and established.

Thermo-optic waveguide gate switch arrays based on direct UV-written highly fluorinated low-loss photopolymer

Novel thermo-optic waveguide gate switch arrays were designed and fabricated based on the direct UV-written technique. Highly fluorinated low-loss photopolymers and organic-inorganic grafting materials were used as the waveguide core and cladding, respectively. The low absorption loss characteristics and excellent thermal stabilities of the core and cladding materials were obtained. The rectangular waveguides and arrayed electrode heaters have been theoretically designed and numerically simulated to realize single-mode transmission. The propagation loss of a 4-μm-wide straight waveguide was measured as 0.15  dB/cm. The insertion loss of the device was directly measured to be about 5.5 dB. The rise and fall times of the device applied 100 Hz square-wave voltage were obtained as 1.068 and 1.245 ms, respectively. The switching power was about 9.2 mW, and the extinction ratio was 17.8 dB. The low-loss integrated switch arrays are suitable for realizing large-scale photonic integrated circuits.

Organic thin film transistors with novel photosensitive polyurethane as dielectric layer

In this paper, we report the design, synthesis, and dielectric properties of a novel photosensitive polyurethane dielectric film used in organic thin-film transistors (OTFTs). The novel photosensitive polyurethane dielectric film is readily fabricated by spin coating followed by curing under UV light. The film exhibits excellent insulating properties, smooth surface, and excellent photosensitive properties. The bottom-gate top-contact para-sexiphenyl (p-6P)/vanadyl-phthalocyanine (VOPc) OTFTs with photosensitive polyurethane films as the dielectric layer exhibit excellent performance with a mobility of 0.13 cm2 V−1 s−1, on/off ratio of 104 and ultralow leakage.

Silver chloride loaded mesoporous silica particles and their application in the antibacterial coatings on denture base

Thiol-functionalized MCM-41 type mesoporous silica particles(MSPs) were prepared and loaded with silver chloride to act as antibacterial agents. The antibacterial activity of the silver chloride loaded MSPs(AgCl-MSPs) was evaluated by the minimum bactericidal concentration(MBC) against Candida albicans(ATCC 10231). The AgCl-MSPs with the highest antibacterial activity were then dispersed in hybrid coatings with different mass ratios to fabricate antibacterial coatings. The antibacterial activity of the coatings was tested against Candida albicans(ATCC 10231) and Streptococcus mutans(ATCC 25175). The resulting antibacterial coatings exhibited high antibacterial activity, good adhesion to the substrate and high hardness.

New strategy for design and fabrication of polymer hydrogel with tunable porosity as artificial corneal skirt

In order to obtain an ideal material using for artificial corneal skirt, a porous polymer hydrogel containing 2-hydroxyethyl methacrylate (HEMA), trimethylolpropane triacrylate (TMPTA) and butyl acrylate was prepared through one-step radical polymerization method and the usage of CaCO3 whisker as porogen. The physical-chemical properties of the fabricated polymer hydrogel can be adjusted by CaCO3 whisker content, such as pore size, porosity, water content of materials and surface topography. Then a series of cell biology experiments of human corneal fibroblasts (HCFs) were carried out to evaluate its properties as an artificial corneal skirt, such as the adhesion of cells on the materials with different pore size and porosity, the apoptosis on materials with different characteristics, the distribution of the cells on the material surface. The results revealed that high porosity not only could improve water content of hydrogel, but also strengthen the adhesion of HCFs on hydrogel. In addition, high porosity hydrogel with the whisker shape of pores showed much elongate spindle-like morphology than those low porosity hydrogels. MTT assay certified that the resulted polymer hydrogel material possessed excellent biocompatibility and was suitable for HCFs growing, making it promising for being developed as artificial corneal skirt.

Fluorinated photopolymer thermo-optic switch arrays with dielectric-loaded surface plasmon polariton waveguide structure

Novel polymer thermo-optic switch arrays were successfully designed and fabricated based on dielectric-loaded surface plasmon polariton waveguide (DLSPPW) structure. Highly fluorinated low-loss photopolymers and organic–inorganic grafting materials were used as the waveguide core and cladding, respectively. The low absorption loss characteristics and excellent thermal stabilities of the core and cladding materials were obtained. The proposed DLSPPW model was included of fluorinated polymer ridge with 4 × 4 μm2 size loaded on 60-nm thin gold stripe electrode heaters, organic-inorganic grafting material cladding and PMMA substrate. The operation of the device at signal wavelengths is controlled via the thermo-optic effect by electrically heating the gold stripes of dielectric-loaded surface plasmon polariton waveguides. The optimized structural properties of dielectric-loaded surface plasmon polariton waveguides were provided. The propagation loss of a 4-μm wide straight DLSPPW was measured as 0.55 dB∕cm at 1550 nm wavelength. The insertion loss of the device was measured to be about 4.5 dB. The switching rise and fall time of the device applied by 200 Hz square-wave voltage were obtained as 287.5 μs and 370.2 μs, respectively. The switching power was about 5.6 mW, and the extinction ratio was about 13.5 dB. The flexible low-loss multi-functional waveguide switch arrays are suitable for realizing large-scale optoelectronic integrated circuits.