Light-directed writing of chemically tunable narrow-band holographic sensors

This tunable holographic sensor offers interrogation and a reporting transducer as well as an analyte-responsive hydrogel, rendering it label-free and reusable. A single 6 ns laser pulse is used to fabricate holographic sensors consisting of silver nanoparticles arranged periodically within a polymer film. The tunability of the sensor is demonstrated through pH sensing of artificial urine and validated through computational modeling. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On-chip focusing of light by metallic nanotip

We present a numerical simulations, fabrication and experimental results for on-chip focusing of surface plasmon polaritons (SPPs) in metal nanotip coupled to the silicon waveguide. © 2011 Optical Society of America.

Physical properties of a hybrid and a nanohybrid dental light-cured resin composite.

This work was aimed at the study of some physical properties of two current light-cured dental resin composites, Rok (hybrid) and Ice (nanohydrid). As filler they both contain strontium aluminosilicate particles, however, with different size distribution, 40 nm-2.5 mum for Rok and 10 nm-1 mum for Ice. The resin matrix of Rok consists of UDMA, that of Ice of UDMA, Bis-EMA and TEGDMA. Degree of conversion was determined by FT-IR analysis. The flexural strength and modulus were measured using a three-point bending set-up according to the ISO-4049 specification. Sorption, solubility and volumetric change were measured after storage of composites in water or ethanol/water (75 vol%) for 1 day, 7 or 30 days. Thermogravimetric analysis was performed in air and nitrogen atmosphere from 30 to 700 degrees C. Surface roughness and morphology of the composites was studied by atomic force microscopy (AFM). The degree of conversion was found to be 56.9% for Rok and 61.0% for Ice. The flexural strength of Rok does not significantly differ from that of Ice, while the flexural modulus of Rok is higher than that of Ice. The flexural strengths of Rok and Ice did not show any significant change after immersion in water or ethanol solution for 30 days. The flexural modulus of Rok and Ice did not show any significant change either after immersion in water for 30 days, while it decreased significantly, even after 1 day immersion, in ethanol solution. Ice sorbed a higher amount of water and ethanol solution than Rok and showed a higher volume increase. Thermogravimetric analysis showed that Rok contains about 80 wt% inorganic filler and Ice about 75 wt%.

Polarization and modal degrees of freedom for tight confinement of light

We describe our work on tight confinement of light using plasmonic structures. Polarization and modal degrees of freedom are shown to have a crucial effect on the nanoscale focusing properties of the optical field. © 2010 Optical Society of America.

On-chip focusing of light by Metallic Nanotip

We investigate numerically and experimentally the on-chip nanoscale focusing of surface plasmon polaritons (SPPs) in metallic nanotip coupled to the silicon waveguide. Strong field enhancement is observed at the apex of the tip. © 2010 Optical Society of America.

Modal control of a 50μm core diameter multimode fiber using a spatial light modulator

An iterative, self-correcting system for doing modal control using adaptive optics in a 50μm core diameter multimode fiber (MMF) is designed. It is shown experimentally to reduce the number of modes generated by 300%. © 2006 Optical Society of America.

Modal control of a 50μm core diameter multimode fiber using a spatial light modulator

An iterative, self-correcting system for doing modal control using adaptive optics in a 50μm core diameter multimode fiber (MMF) is designed. It is shown experimentally to reduce the number of modes generated by 300%. © 2006 Optical Society of America.

Light induced instability mechanism in amorphous InGaZn oxide semiconductors

A model of the negative bias illumination stress instability in InGaZn oxide is presented, based on the photo-excitation of electrons from oxygen interstitials. The O interstitials are present to compensate hydrogen donors. The O interstitials are found to spontaneously form in O-rich conditions for Fermi energies at the conduction band edge, much more easily that in related oxides. The excited electrons give rise to a persistent photoconductivity due to an energy barrier to recombination. The formation energy of the O interstitials varies with their separation from the H donors, which leads to a voltage stress dependence on the compensation. © 2014 AIP Publishing LLC.