| 1. |
- Bora, Tanujjal, et al.
(författare)
-
Controlled side coupling of light to cladding mode of ZnO nanorod coated optical fibers and its implications for chemical vapor sensing
- 2014
-
Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 202, s. 543-550
-
Tidskriftsartikel (refereegranskat)abstract
- Controlled light coupling from surrounding to the cladding mode of zinc oxide (ZnO) nanorod coated multimode optical fiber induced by the light scattering properties of the nanorod coating and their applications of sensing are reported here. A dense and highly ordered array of ZnO nanorods is grown on the cladding of silica fibers by using low temperature hydrothermal process and the effect of the hydrothermal growth conditions of the nanorods on the light scattering and coupling to the optical fibers is experimentally investigated. The nanorod length and its number per unit area are found to be most crucial parameters for the optimum side coupling of light into the fibers. Maximum excitation of the cladding mode by side coupling of light is obtained with ZnO nanorods of length similar to 2.2 mu m, demonstrating average coupling efficiency of similar to 2.65%. Upon exposure to different concentrations of various chemical vapors, the nanorod coated fibers demonstrated significant enhancement in the side coupled light intensity, indicating the potential use of these ZnO nanorod coated fibers as simple, low cost and efficient optical sensors. The sensor responses to methanol, ethanol, toluene and benzene vapor were investigated and compared, while the effect of humidity in the sensing environment on the sensor performance was explored as well.
|
|
| 2. |
- Fallah, H., et al.
(författare)
-
Demonstration of side coupling to cladding modes through zinc oxide nanorods grown on multimode optical fiber
- 2013
-
Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 38:18, s. 3620-3622
-
Tidskriftsartikel (refereegranskat)abstract
- A novel concept is introduced that utilizes the scattering properties of zinc oxide nanorods to control light guidance and leakage inside optical fibers coated with nanorods. The effect of the hydrothermal growth conditions of the nanorods on light scattering and coupling to optical fiber are experimentally investigated. At optimum conditions, 5% of the incident light is side coupled to the cladding modes. This coupling scheme could be used in different applications such as distributed sensors and light combing. Implementation of the nanorods on fiber provides low cost and controllable nonlithography-based solutions for free space to fiber coupling. Higher coupling efficiencies can be achieved with further optimization.
|
|
| 3. |
- Fallah, Hoorieh, et al.
(författare)
-
Excitation of core modes through side coupling to multimode optical fiber by hydrothermal growth of ZnO nanorods for wide angle optical reception
- 2014
-
Ingår i: Journal of the Optical Society of America. B, Optical physics. - : Optical Society of America. - 0740-3224 .- 1520-8540. ; 31:9, s. 2232-2238
-
Tidskriftsartikel (refereegranskat)abstract
- Side coupling to core modes through zinc oxide (ZnO) nanorods grown around the fiber is demonstrated in this work. The scheme utilizes wet etching of the cladding region followed by hydrothermal growth of the nanorods. The combination of nanostructures and the optical fiber system is used to demonstrate a simple wide field of view (FOV) optical receiver. Core modes are excited by the light scattered in the region where the fiber core is exposed. The angular response of the receiver was tested using a nephlometer. Light coupling efficiency was extracted by deconvoluting the finite beam extinction from the measured power. The results were compared to a first-order analytical model in which the phase function is assumed to linearly shift with the incident angle. The trend of the experimental measurements agrees with the model. 180 degrees FOV is verified, and maximum coupling efficiency of around 2.5% for a single fiber is reported. Excitation of core modes through side coupling shows potential for the application of these devices in optical receivers and sensors.
|
|
| 4. |
|
|
| 5. |
- Viphavakit, C., et al.
(författare)
-
Development of integrated microfluidic device for optical flow rate sensing
- 2013
-
Ingår i: Journal of Circuits, Systems and Computers. - : World Scientific. - 0218-1266 .- 1793-6454. ; 22:9
-
Tidskriftsartikel (refereegranskat)abstract
- The design, fabrication and characterization of an optics based integrated flow rate sensor is presented where the light-fluid interaction is maximized by allowing the liquid and light to propagate along the same direction. The flow rate sensor consists of a 10 mu m deep microchannel placed between two waveguides. The optical waveguides were tapered to fit the channel width, to guide light in and out of the microchannel. A tapering mechanism is proposed to minimize the coupling and propagation losses. The power of the output signal from the designed device was calculate through simulation and it was compared with the actual output signal detected by a fast receiver (higher than 1 MHz). The dynamic change of the light intensity when fluid flows through the channel can also be recorded by this receiver. This scheme allows for a direct measurement of the liquid flow rate with higher interaction length between fluid and light with a dynamic range of up to 0.18. An integrated microfluidic device with high precision and sufficient coupling between the light source and the microfluidic channel is proposed.
|
|
| 6. |
- Viphavakit, Charusluk, et al.
(författare)
-
Development of integrated optical characterization bench for sensing microfluidic channel
- 2012
-
Konferensbidrag (refereegranskat)abstract
- This work introduces design, fabrication and characterization of an optical based integrated flow rate sensor where the light- fluid interaction is maximized by allowing the liquid and light to propagate along the same direction. This is achieved by placing a 10 μm deep channel between two waveguides. The optical waveguides are tapered down to the channel width to feed the light in and out, where tapering is done to minimize the coupling and propagation loss. The output signal is detected by a fast receiver (higher than 1MHz) that records the dynamic change of the light intensity when fluid flows through the channel. The initial results showed a dynamic range of measurement up to 0.18.
|
|
| 7. |
- Abelev, Betty, et al.
(författare)
-
Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
-
Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
|
|
| 8. |
- Abelev, Betty, et al.
(författare)
-
Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
-
Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
|
|
| 9. |
|
|
| 10. |
- Borah, Sandhya Banti Dutta, et al.
(författare)
-
Heavy Metal Ion Sensing By Surface Plasmon Resonance on Gold Nanoparticles
- 2014
-
Ingår i: ADBU Journal of Engineering Technology. - : Don Bosco University. - 2348-7305. ; 1
-
Tidskriftsartikel (refereegranskat)abstract
- Surface Plasmon resonance (SPR) based heavy metal ions sensor is one of the most sensitive sensor for detecting toxic metal ions. It is an inexpensive, portable and also feasible for real time detection. SPR sensor is a type of optical sensor in which toxic metal ions get adsorbed on the functionalized metal (mostly Au) film causes the change in refractive index of the metal (Au)-dielectric (sensing) medium. The change of the refractive index leads to a shift in the angular spectrum of the reflected light and can be accurately monitored by optical methods. In this paper,we are trying to optimize the detection level of heavy metal ions by surface plasmon resonance on gold nanoparticles using UV-VIS spectroscopy. Polymer like chitosan is being used with gold nanoparticles to detect copper and zinc ions and detection till very low concentrations of the toxic metal ions is obtained.
|
|
