Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
Search results
11 records were found.
Experimental measurements on waveguide Mach-Zehnder interferometers are presented which show that order of magnitude improvements in the sensitivity of planar waveguide sensors can be achieved by incorporating thin high index overlays
The proportion of power carried in the superstrate medium by the guided modes of integrated optical waveguides can be increased by the addition of a thin high index film. Enhanced refractive index sensing is demonstrated using channel waveguide Mach-Zehnder interferometers with Ta2O5 overlayers. Sensitivity increases by a factor greater than 50, and a detection limit better than 5x10^-7 are obtained. This approach is broadly applicable to sensing at waveguide surfaces where the strength of evanescent fields dictates performance.
The fabrication and operation of robust integrated optical refractometers, suitable for precise measurements of small changes without ambiguity over a wide range of refractive indices, is described. The design primarily uses an optical fibre coupled dual-sensitivity integrated optical Mach–Zehnder interferometer (MZI) sensor chip incorporating 3×3 directional coupler combiners and internal referencing. High-index tantalum pentoxide (Ta2O5) films were deposited on the waveguide surface in order to increase sensitivity and measurements of their response to liquid analyte index have been carried out by passing aqueous sucrose solutions over the sensor surface. These devices are intended for application as high-sensitivity multi-purpose chemical sensors and bio-sensors.
The fabrication and operation of robust integrated optical refractometers, suitable for precise measurements of small changes without ambiguity over a wide range of refractive indices, is described. The design primarily uses an optical fibre coupled dual-sensitivity integrated optical Mach-Zehnder Interferometer sensor chip incorporating 3x3 directional coupler combiners and internal referencing. High-index Ta2O5 films were deposited on the waveguide surface in order to increase sensitivity and measurements of their response to liquid analyte index have been carried out by passing aqueous sucrose solutions over the sensor surface. These devices are intended for application as high-sensitivity multi-purpose chemical sensors and biosensors.
The fabrication and operation of robust integrated optical refractometers, suitable for precise measurements of small changes without ambiguity over a wide range of refractive indices, is described. The design primarily uses an optical fibre coupled dual-sensitivity integrated optical Mach-Zehnder Interferometer sensor chip incorporating 3x3 directional coupler combiners and internal referencing. High-index Ta2O5 films were deposited on the waveguide surface in order to increase sensitivity and measurements of their response to liquid analyte index have been carried out by passing aqueous sucrose solutions over the sensor surface. These devices are intended for application as high-sensitivity multi-purpose chemical sensors and biosensors.
Following the recent realisation of a Ti:sapphire waveguide laser by Ti-indiffusion, the relation between diffusion conditions, waveguide properties and Ti spectroscopy is discussed in depth with a view to developing a next-generation device
A regenerable channel waveguide fluorescence sensor for environmental monitoring is reported. The sensor has been characterised as a detector of the pesticide 2,4 dichlorophenoxyacetic acid. A binding inhibition assay, using fluorescent Cy5.5 dye-labelled antibodies, was monitored at the modified surface of the glass waveguide to detect the target analyte. Three calibration curves were determined and averaged. The averaged calibration curve has a mid-point of 0.68 ppb and a calculated detection limit of 0.28 ppb. Incorporation of a 20 nm thick tantalum pentoxide film at the waveguide surface enhanced the peak fluorescence signal by a factor of approximately 6 compared with an uncoated sensor. Due to the high optical field strengths at the surface of the waveguide, which is approximately 10µm wide, significant photobleaching of the dye...
We demonstrated a bulk optical fluorescence based immunosensor capable for multianalyte water analysis. Calibration curves obtained for 2,4-dichlorophenoxyacetic acid (2,4-D) and simazine had detection limits of 0.035 µg/l and 0.026 µg/1 respectively. The sensor is reusable due to its regenerability and cost effective due to the use of components customary in the trade. Ways to further enhance device sensitivity by means of a high index film deposited on the sensor surface or by employing an integrated optical waveguide as transducer are presented. A concept for the detection of a varying range of analytes on the same transducer is discussed.
We have demonstrated a regenerable waveguide fluorescence sensor for environmental monitoring. Characterisation of the sensor as a detector of the pesticide 2,4 dichlorophenoxyacetic acid in water is presented. A binding inhibition assay, using fluorescent Cy5.5 dye-labelled antibodies, was monitored at the modified surface of the glass waveguide to detect the target analyte. Incorporation of a thin high-index film at the waveguide surface enhanced device sensitivity
We demonstrated a bulk optical fluorescence based immunosensor capable of multianalyte water analysis. Calibration curves obtained for 2.3-dichlorophenoxyacetic acid (2,4-D) and simazine had detection limits of 0.035µg/l and 0.026µg/l respectively. The sensor is reusable due to its regenerability and cost effective due to the use of components customary in the trade. Ways to further enhance device sensitivity by means of a high index film deposited on the sensor surface or by employing an integrated optical waveguide as transducer are presented. A concept for the detection of a varying range of analytes on the same transducer is discussed.
