Oxidizing Hexagonal Boron Nitride into Fluorescent Structures by Photodissociated Directional Oxygen Radical.

Modifying the wide band gap semiconductor hexagonal boron nitride (hBN) can bring new chances in photonics. By virtue of the solvothermal/hydrothermal oxidation or functionalization, hBN can be converted into fluorescent nanodots. Until now, it has been a big challenge to drily oxidize hBN and turn it into bright fluorescent structures due to its superior chemical stability.

Patterning Graphene Films by HO-Based Magnetic-Assisted UV Photolysis.

Properly cutting graphene into certain high-quality micro-/nanoscale structures in a cost-effective way has a critical role. Here, we report a novel approach to pattern graphene films by HO-based magnetic-assisted ultraviolet (UV) photolysis under irradiation at 184.9 nm.

UV Rewritable Hybrid Graphene/Phosphor p-n Junction Photodiode.

Graphene-based p-n junction photodiodes have a potential application prospect in photodetection due to their broadband spectral response, large operating bandwidth, and mechanical flexibility. Here, we report an ultraviolet (UV) rewritable p-n junction photodiode in a configuration of graphene coated with an amorphous phosphor of 4-bromo-1,8-naphthalic anhydride derivative polymer (poly-BrNpA). Under moderate UV irradiation, occurrence of photoisomerization reaction in the poly-BrNpA film leads to its drastically modified optical characteristics and a concurrent n-type doping in the underneath graphene.

Exploring the working mechanism of graphene patterning by magnetic-assisted UV ozonation.

When assisted with an inhomogenous vertical magnetic field, ultraviolet (UV) ozonation turns directional and is testified to be applicable to graphene patterning. Using a more cost-effective low-pressure mercury lamp, we further explore the underlying working mechanism by changing oxygen content, introducing reactive ozone or inert nitrogen molecules, and study the lateral under-oxidation impeded Dirac point shifts for a graphene field-effect transistor under UV irradiation. The paramagnetic oxygen molecule XΣ accelerates toward graphene with the magnetic moment aligned parallel to the magnetic field.

Patterning Graphene Film by Magnetic-assisted UV Ozonation.

Developing an alternative method for fabricating microscale graphene patterns that overcomes the obstacles of organic contamination, linewidth resolution, and substrate damaging is paramount for applications in optoelectronics. Here we propose to pattern chemical vapor deposition grown graphene film through a stencil mask by magnetic-assisted ultraviolet (UV) ozonation under irradiation of a xenon excimer lamp. In this process, the paramagnetic oxygen molecules and photochemically generated oxygen radicals are magnetized and attracted in an inhomogenous external magnetic field.

Near-field observation of anomalous optical propagation in photonic crystal coupled-cavity waveguides.

An air-bridged silicon-based photonic crystal coupled-cavity waveguide (PCCCW) connected with an input and output W1 PC waveguide (PCW) was designed and fabricated. We mapped its intensity distributions with a near-field scanning optical microscope (NSOM) at near-infrared wavelengths around 1550 nm. Surprisingly, the intensity distributions demonstrate that the second odd eigenmode dominates in such a PCCCW, even though it possesses a much slower group velocity of light than that of the first even one.

Damaging graphene with ozone treatment: a chemically tunable metal-insulator transition.

We present a multiscale ab initio study of electronic and transport properties of two-dimensional graphene after epoxide functionalization via ozone treatment. The orbital rehybridization induced by the epoxide groups triggers a strong intervalley scattering and changes dramatically the conduction properties of graphene. By varying the coverage density of epoxide defects from 0.

Nanolithography in the quasi-far field based on the destructive interference effect of surface plasmon polaritons.

On the principle of phase-shift mask, the metal segment of a sub-wavelength Ag grating on a quartz substrate is used as a phase-shifting layer in this photolithography method. When the radiation modes of the surface plasmon polaritons (SPPs) excited on the Ag surface have optical phase opposite to that of the waves emitting from the slits, destructive interference occurs and the diffraction limit can be broken through. The SPPs excited on the surface between Ag and water can be transformed into propagation modes in the photoresist.

Cordyceamides A and B from the Culture Liquid of Cordyceps sinensis (BERK.) SACC.

Two new aurantiamides named as cordyceamides A and B were isolated from the culture liquid of Cordyceps sinensis (BERK.) SACC., along with one known compound, aurantiamide acetate.

High resolution three-port filter in two dimensional photonic crystal slabs.

An in-plane, three-port filter consisting of input/output waveguides and two point-defect cavities in a 2D PC slab is designed and fabricated, where a new feedback method is introduced, and its transmission properties are measured. The measured minimum output wavelength spacing between two channels is 1.5 nm, which is realized by slightly adjusting the size of the resonant cavities.