This critical review will be of interest to the experts in porous solids (including catalysis), but also solid state chemists and physicists. It presents the state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their ‘design’, aiming at reaching very large pores. Their dynamic properties and the possibility of predicting their structure are described. The large tunability of the pore size leads to unprecedented properties and applications. They concern adsorption of species, storage and delivery and the physical properties of the dense phases. (323 references)

Hybrid porous solids: past, present, future

http://experimentationlab.berkeley.edu/sites/default/files/AFMImages/butt_AFM.pdf

Force measurements with the atomic force microscope: Technique, interpretation and applications

Femtosecond laser micromachining can be used either to remove materials or to change a material's properties, and can be applied to both absorptive and transparent substances. Over the past decade, this technique has been used in a broad range of applications, from waveguide fabrication to cell ablation. This review describes the physical mechanisms and the main experimental parameters involved in the femtosecond laser micromachining of transparent materials, and important emerging applications of the technology. Interactions between laser and matter are fascinating and have found a wide range of applications. This article gives an overview of the fundamental physical mechanisms in the processing of transparent materials using ultrafast lasers, as well as important emerging applications of the technology.

Femtosecond laser micromachining in transparent materials

This review covers important advances in recent years in the physics of thin-film ferroelectric oxides, the strongest emphasis being on those aspects particular to ferroelectrics in thin-film form. The authors introduce the current state of development in the application of ferroelectric thin films for electronic devices and discuss the physics relevant for the performance and failure of these devices. Following this the review covers the enormous progress that has been made in the first-principles computational approach to understanding ferroelectrics. The authors then discuss in detail the important role that strain plays in determining the properties of epitaxial thin ferroelectric films. Finally, this review ends with a look at the emerging possibilities for nanoscale ferroelectrics, with particular emphasis on ferroelectrics in nonconventional nanoscale geometries.

/pdf/physics-of-thin-film-ferroelectric-oxides-3zmqphtpv1.pdf

Physics of thin-film ferroelectric oxides

Two-photon excitation provides a means of activating chemical or physical processes with high spatial resolution in three dimensions and has made possible the development of three-dimensional fluorescence imaging, optical data storage, and lithographic microfabrication. These applications take advantage of the fact that the two-photon absorption probability depends quadratically on intensity, so under tight-focusing conditions, the absorption is confined at the focus to a volume of order λ3 (where λ is the laser wavelength). Any subsequent process, such as fluorescence or a photoinduced chemical reaction, is also localized in this small volume. Although three-dimensional data storage and microfabrication have been illustrated using two-photon-initiated polymerization of resins incorporating conventional ultraviolet-absorbing initiators, such photopolymer systems exhibit low photosensitivity as the initiators have small two-photon absorption cross-sections (δ). Consequently, this approach requires high laser power, and its widespread use remains impractical. Here we report on a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators. Two-photon excitable resins based on these new initiators have been developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of three-dimensional micro-optical and micromechanical structures, including photonic-bandgap-type structures.

Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication

Near infrared broadband emission characteristics of bismuth-doped aluminophosphate glass have been investigated. Broad infrared emissions peaking at 1210nm, 1173nm and 1300nm were observed when the glass was pumped by 405nm laser diode (LD), 514nm Ar+ laser and 808nm LD, respectively. The full widths at half maximum (FWHMs) are 235nm, 207nm and 300nm for the emissions at 1210nm, 1173nm and 1300nm, respectively. Based on the energy matching conditions, it is suggested that the infrared emission may be ascribed to 3P1→ 3P0 transition of Bi+. The broadband infrared luminescent characteristics of the glasses indicate that they are promising for broadband optical fiber amplifiers and tunable lasers.

/pdf/near-infrared-broadband-emission-of-bismuth-doped-24akm4yjck.pdf

Near infrared broadband emission of bismuth-doped aluminophosphate glass

Broadband infrared luminescence from bismuth-doped germanium oxide glasses prepared by a conventional melting-quenching technique was discovered. The absorption spectrum of the glasses covered a wide range from the visible to the near-infrared wavelength regions and consisted of five broad peaks below 370, 500, 700, 800, and 1000 nm. The fluorescence spectrum exhibited broadband characteristics (FWHM) greater than 300 nm with a maximum at 1300 nm pumped by an 808-nm laser. The fluorescence lifetime at room temperature decreased with increasing Bi2O3 concentration in the glass. Codoping of aluminum and bismuth was indispensable for the broadband infrared luminescence in GeO2:Bi, Al glass.

Bismuth- and aluminum-codoped germanium oxide glasses for super-broadband optical amplification

We report near infrared broadband emission of bismuth-doped barium-aluminum-borate glasses. The broadband emission covers 1.3 mum window in optical telecommunication systems. And it possesses wide full width at half maximum (FWHM) of similar to 200nm and long lifetime as long as 350 mus. The luminescent properties are quite sensitive to glass compositions and excitation wavelengths. Based on energy matching conditions, we suggest that the infrared emission may be ascribed to P-3(1) --> P-3(0) transition of Bi+. The broad infrared emission characteristics of this material indicate that it might be a promising candidate for broadband optical fiber amplifiers and tunable lasers. (C) 2005 Optical Society of America.

/pdf/infrared-broadband-emission-of-bismuth-doped-barium-aluminum-4tq2fctp34.pdf

Infrared broadband emission of bismuth-doped barium-aluminum-borate glasses.

Near-infrared broadband emission from bismuth-tantalum-codoped germanium oxide glasses was observed at room temperature when the glasses were pumped by an 808 nm laser diode. The emission band covered the 0, E, S, C, and L bands (1260-1625 nm), with a maximum peak at similar to 1310 nm, a FWHM broader than 400 nm, and a lifetime longer than 200 lis. The observed broadband luminescence was attributed to bismuth clusters in the glasses. Bismuth-tantalum-codoped germanium oxide glass might be promising as amplification media for broadly tunable lasers and wideband amplifiers in optical communications. (c) 2005 Optical Society of America.

Superbroadband 1310 nm emission from bismuth and tantalum codoped germanium oxide glasses

Nanoparticles have a wide range of electrical and optical properties owing to the quantum-size effect, surface effect, and conjoint effect of nanostructures.[1] Materials doped with noble-metal nanoparticles exhibit large third-order nonlinear susceptibility and ultrafast nonlinear responses.[2] They are expected to be promising materials for ultrafast all-optical switches in the THz region. For the applications related to integrated optoelectronics, a well-defined assembly and spatial distribution of nanoparticles in materials are essential.[3] Many studies have been carried out on the fabrication of nanoparticle-doped materials,[4] but there are no effective methods to control the spatial distribution of nanoparticles in these materials. In addition, Zheng and Dickson reported the synthesis of photostable, water-soluble, silver nanodots by direct photoreduction of silver ions under ambient conditions.[5] Photoactivated fluorescence has also been observed from individual silver nanoclusters.[6] Herein, we report a method that can control the precipitation of Au nanoparticles in three dimensions inside transparent materials by using focused femtosecond laser irradiation. In brief, the precipitation involves two processes: the photoreduction of Au ions to atoms induced by multiphoton process, and the precipitation of Au particles driven by heat treatment. The size of nanoparticles and their spatial distribution can be controlled by the conditions of the lasermore » irradiation. Interestingly, the precipitated nanoparticles obtained by this technique can be also space-selectively “dissolved” by the femtosecond laser irradiation, and reprecipitated by annealing. This implies that the laser can be used not only in practical applications, such as the 3D optical memory and the fabrication of integrated alloptical switches, but also in the study of the control of nucleation and crystal growth.« less

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/anie.200352380

Congshan Zhu

Papers

Near infrared broadband emission of bismuth-doped aluminophosphate glass

Bismuth- and aluminum-codoped germanium oxide glasses for super-broadband optical amplification

Infrared broadband emission of bismuth-doped barium-aluminum-borate glasses.

Superbroadband 1310 nm emission from bismuth and tantalum codoped germanium oxide glasses

Manipulation of gold nanoparticles inside transparent materials.