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A silicon surface with distinctive structures is fabricated by ultrashort pulsed-laser ablation and chemical etching with acidic fluoride solutions. The surface consists of micro/nanostructures that result in the quasi-superhydrophobicity of the silicon surface. By fine tuning a key process parameter (i.e., pulsed laser power), surfaces with different wettability are fabricated. The morphology and composition of the surfaces are characterized by scanning electron microscopy, which reveals nanopores. The contact angle of water on these surfaces was measured and found to be as high as 150° at optimized parameters. This work presents a novel process of fabricating a silicon-based quasi-superhydrophobic porous surface.

A series of copper coordination polymers of [Cu3(OH)2(5-iipa)2(phen)3(H2O)·4.5(H2O)]n (1) [Cu(5-iipa)(phen)(H2O)]n (2), [Cu(5-iipa)(bpe)·2(H2O)]n (3), [Cu(5-iipa)(p-bix)]n (4), [Cu(5-iipa)(bbi)]n (5), [Cu2(5-iipa)2(bbi)·0.5(H2O)]n (6), and [Cu(5-iipa)(bpp)·H2O]n (7) (phen = 1,10-phenanthroline, bpe = 1,2-bis(4-pyridyl)ethane, p-bix = 1,4-bis(imidazol-1-ylmethyl)-benzene, bbi = 1,1′-(1,4-butanediyl)bis(imidazole), bpp = 1,3-bi(4-pyridyl)propane) were hydro(solvo)thermally synthesized through the reaction of divalent copper salts, 5-iodo-isophthalic acid (5-H2iipa), and N-donor ancillary ligands. Single-crystal X-ray diffraction analyses on these complexes revealed that noncovalent interactions were found to be predominant in constructing these supramolecular architectures. Compounds 1–5 all possess three-dimensional (3D) supramolecular structures based on O···I, I···I, I···π, and π···π interactions. Compound 6 exhibits a complicated three-dimensional (3D) framework with a new (6·72)2(63·72·8)2(63·78·82·92)...

A polar homochiral 3D MOF [{Co2(L)(bpe)(H2O)}·5H2O]n constructed with cobalt(II) and a new ligand N-(1,3-dicarboxy-5-benzyl)-carboxymethylglycine (H4L) accommodates ordered helical water streams in its helical grooves. It provides the first example of switchable ferroelectric and optical behavior through two-step reversible single-crystal to single-crystal transformation (SCSC) upon desorption/adsorption of water spirals and coordinated water molecules, respectively.

A metal-organic framework based on 5-iodo-isophthalic acid (5-iipaH2) and the ancillary nitrogen ligand 1,3-bi(4- pyridyl)propane (bpp), namely [Cd(5-iipa)(bpp)(H2O)]n (1), has been synthesized, and characterized by IR spectroscopy, elemental analysis, thermogravimetry, and X-ray crystallography. Complex 1shows a two-fold interpenetrating 3D diamond-like architecture that is stabilized by hydrogen bonding, μ...μ, I...μ, and C-H...p interactions.

A 10-mm-long cylindrical shell was written in neodymium doped phosphate glass by a femtosecond laser delivering pulses with a pulse repetition of 1 kHz, energies of 90 uJ and duration of 120 fs. The pulses were focused below the glass surface by an objective producing ablation filaments about 200 um in length. During processing, the sample was placed on a three-dimensional (3-D) translation stage, which moved along an enclosed pattern in the horizontal plane followed by a minor descent less than the filament length in the vertical direction. As this procedure continued, a cylinder, which demonstrated optical waveguiding, was fabricated with a rarified periphery and densified center region due to plasmonic expansion and outward shockwave upon laser ablation. The refractive-index contrast, propagation loss, near- and farfield mode distribution, and microscopic fluorescence micrograph of the waveguides were measured. 1-to-N splitters with adjustable splitting ratio were also fabricated using current approach indicating its 3-D processing flexibility. Compared with previous femtosecond laser fabrication methods, waveguides prepared in this approach exploit both depressed cladding and stress-induced refractive index increase in core region and show controllable mode conduction, strong field confinement, large numerical aperture, low propagation loss, acceptable thermal stability and intact core region.

We report on the fabrication of stress-induced optical channel waveguides and waveguide splitters with laser-depressed cladding by femtosecond laser. The laser beam was focused into neodymium doped phosphate glass by an objective producing a destructive filament. By moving the sample along an enclosed routine in the horizontal plane followed by a minor descent less than the filament length in the vertical direction, a cylinder with rarified periphery and densified center region was fabricated. Lining up the segments in partially overlapping sequence enabled waveguiding therein. The refractive-index contrast, near- and far-field mode distribution and confocal microscope fluorescence image of the waveguide were obtained. 1-to-2, 1-to-3 and 1-to-4 splitters were also machined with adjustable splitting ratio. Compared with traditional femtosecond laser writing methods, waveguides prepared by this approach showed controllable mode conduction, strong field confinement, large numerical aperture, low propagation loss and intact core region.