Matthew R. Jorgensen

Diamond-structured titania photonic-bandgap crystals from biological templates.

Adv. Mater. 2010, 22, 107–11

Study of natural photonic crystals in beetle scales and their conversion into inorganic structures via a sol–gel bio-templating route

The origin of the structural colors from several different examples of the weevil and longhorn families (Curculionidae and Cerambycidae, respectively) was investigated by structural and optical characterization techniques. A range of interesting three-dimensional photonic crystal structures operating at visible wavelengths was discovered, including both disordered and ordered non-close-packed lattices of cuticular spheres and bicontinuous diamond-based architectures. The discovered photonic structures display a large variation in lattice constants and dielectric filling fractions and thereby create optical reflectance colors spanning the entire visible range. To transform these bio-polymeric photonic crystals into heat and photo-stable inorganic structures, a low-temperature bio-templating method was developed. Using organic–inorganic hybrid silica sol–gel infiltration–templation chemistry combined with acid-etching template removal, stable inverse photonic structures were fabricated. The inverse structures display good structural quality and vivid reflection properties.

Ultrasmall SnO 2 Nanocrystals: Hot-bubbling Synthesis, Encapsulation in Carbon Layers and Applications in High Capacity Li-Ion Storage

Ultrasmall SnO2 nanocrystals as anode materials for lithium-ion batteries (LIBs) have been synthesized by bubbling an oxidizing gas into hot surfactant solutions containing Sn-oleate complexes. Annealing of the particles in N2 carbonifies the densely packed surface capping ligands resulting in carbon encapsulated SnO2 nanoparticles (SnO2/C). Carbon encapsulation can effectively buffer the volume changes during the lithiation/delithiation process. The assembled SnO2/C thus deliver extraordinarily high reversible capacity of 908 mA·h·g−1 at 0.5 C as well as excellent cycling performance in the LIBs. This method demonstrates the great potential of SnO2/C nanoparticles for the design of high power LIBs.

Photoactive rolled-up TiO2 microtubes: fabrication, characterization and applications

The properties of TiO2 within rolled-up nanotechnology are explored. Micromotors and optical microresonators are presented as possible applications.

Biotemplating routes to three-dimensional photonic crystals

The strikingly colorful world of insects is in large part the result of light interacting with periodically organized biopolymeric structures incorporated into wings, hairs and exoskeletons. Such structural colors have recently gained tremendous interest as photonic crystals with their ability to control the behavior of light in revolutionary new ways. This highlight article reviews recent developments in employing biological structures as unique templates for the fabrication of inorganic photonic crystals. Different biotemplating methods, including atomic layer deposition, conformal-evaporated-film-by-rotation and sol–gel chemistry, are introduced and discussed. Under optimized conditions these methods produce high-fidelity inorganic replica structures with improved sensing, light emission and photonic band gap properties.

Vertically aligned rolled-up SiO2 optical microcavities in add-drop configuration

A significant step towards integrated vertically rolled-up microcavities is demonstrated by interfacing an as-fabricated SiO2 microtube optical ring resonator with tapered fibers. In this transmission configuration, resonant filtering of optical signals at telecommunication wavelengths is shown in subwavelength thick walled microcavities. Moreover, we present a four-port add-drop filter based on a lifted doubly interfaced vertically rolled-up microcavity. Our work opens opportunities for vertical resonant light transfer in 3D multi-level optical data processing as well as for massively parallel optofluidic analysis of biomaterials in lab-on-a-chip systems.

Dynamic Molecular Processes Detected by Microtubular Opto-chemical Sensors Self-Assembled from Prestrained Nanomembranes

Libo Ma , * Shilong Li , Vladimir A. Bolanos Quinones , Lichun ang , Y Wang Xi , Matthew Jorgensen , Stefan Baunack , ongfeng Y Mei , Suwit Kiravittaya , and Oliver G. Schmidt

Rolled-up TiO 2 optical microcavities for telecom and visible photonics

The fabrication of high-quality-factor polycrystalline TiO₂ vertically rolled-up microcavities (VRUMs) by the controlled release of differentially strained TiO₂ bilayered nanomembranes, operating at both telecom and visible wavelengths, is reported. Optical characterization of these resonators reveals quality factors as high as 3.8×10³ in the telecom wavelength range (1520-1570 nm) by interfacing a TiO₂ VRUMs with a tapered optical fiber. In addition, a splitting in the fundamental modes is experimentally observed due to the broken rotational symmetry in our resonators. This mode splitting indicates coupling between clockwise and counterclockwise traveling whispering gallery modes of the VRUMs. Moreover, we show that our biocompatible rolled-up TiO₂ resonators function at several positions along the tube, making them promising candidates for multiplexing and biosensing applications.

Enhanced optical axial confinement in asymmetric microtube cavities rolled up from circular-shaped nanomembranes

Asymmetric cone-like microtube cavities have been fabricated by unevenly rolling-up prestrained SiO/SiO(2) circular-shaped nanomembranes. Spatially localized axial resonant modes are obtained due to an axial confinement mechanism that is defined by the variation of the tube radius and windings along the tube axis. A theoretical model is applied to quantitatively explain and confirm our experimental results.

Spin–orbit coupling of light in asymmetric microcavities

When spinning particles, such as electrons and photons, undergo spin–orbit coupling, they can acquire an extra phase in addition to the well-known dynamical phase. This extra phase is called the geometric phase (also known as the Berry phase), which plays an important role in a startling variety of physical contexts such as in photonics, condensed matter, high-energy and space physics. The geometric phase was originally discussed for a cyclically evolving physical system with an Abelian evolution, and was later generalized to non-cyclic and non-Abelian cases, which are the most interesting fundamental subjects in this area and indicate promising applications in various fields. Here, we enable optical spin–orbit coupling in asymmetric microcavities and experimentally observe a non-cyclic optical geometric phase acquired in a non-Abelian evolution. Our work is relevant to fundamental studies and implies promising applications by manipulating photons in on-chip quantum devices.