235 research outputs found

    Fabrication and characterization of high quality factor silicon nitride nanobeam cavities

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    Si3N4 is an excellent material for applications of nanophotonics at visible wavelengths due to its wide bandgap and moderately large refractive index (n \approx 2.0). We present the fabrication and characterization of Si3N4 photonic crystal nanobeam cavities for coupling to diamond nanocrystals and Nitrogen-Vacancy centers in a cavity QED system. Confocal micro-photoluminescence analysis of the nanobeam cavities demonstrates quality factors up to Q ~ 55,000, which is limited by the resolution of our spectrometer. We also demonstrate coarse tuning of cavity resonances across the 600-700nm range by lithographically scaling the size of fabricated devices. This is an order of magnitude improvement over previous SiNx cavities at this important wavelength range

    Photonic Crystal Nanobeam Cavity Strongly Coupled to the Feeding Waveguide

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    A deterministic design of an ultrahigh Q, wavelength scale mode volume photonic crystal nanobeam cavity is proposed and experimentally demonstrated. Using this approach, cavities with Q>10^6 and on-resonance transmission T>90% are designed. The devices fabricated in Si and capped with low-index polymer, have Q=80,000 and T=73%. This is, to the best of our knowledge, the highest transmission measured in deterministically designed, wavelength scale high Q cavities

    Fabrication of organic and inorganic nanoparticles using electrospray

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    A new fabrication process of organic and inorganic nanoparticles and cups by electrospraying blended polymer-sol-gel solutions followed by calcination has been investigated. Because of low viscosity and high surface tension of blended polymersol- gel solutions, an electrostatically extruded continuous liquid jet from the spray source became tiny droplets with diameter of less than 1µm in transit. They were collected as dried formats at the counter electrode. These are then calcinated to eliminate polymers as well as cross-link sol-gel material. Silica nanocups have been fabricated using the above technique and the probable methods to control their morphology by varying the ionic concentration have been investigated. Experiments with biodegradable polymers, like Poly Lactic Acid (PLA) and polyvinylpyrrolidine (PVP) to fabricate nanoparticles using the above technique, have also been carried out. The potential use of such biodegradable particles in drug delivery has been demonstrated. This method can encapsulate drug in the particles without the need of any stabilizer which can cause unwanted effect on the drug. The effect of solvents, polymer concentration and deposition distance on morphology and diameter of particles was also investigated on PLA particles. This process is a simple and efficient approach for producing nanocomposite cups that cannot be made by an aggregation method and also nano/micro particles which may find their use in drug delivery and filtration media. Finally, a new technique to sort the particles based on their dimensions is demonstrated. Because of interactions between charged droplets and a non-linear electrostatic field, nanoparticles with different dimensions are deposited at different locations. By using this principle, silica nanocups have been sorted into three groups with mean diameters of 0.31 µm, 0.7 µm and 1.1µm and a standard deviation of 20%
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