Eylem Seç
Research and Development of Optical Fibre Sensors Based on Thin Film Coating Technology
Başlık:
Research and Development of Optical Fibre Sensors Based on Thin Film Coating Technology
Yazar:
Coelho, Luís Carlos Costa, author.
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (275 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-07C.
Özet:
This thesis presents theoretical and experimental results obtained in the research and development of specific structures in optical fibres coated with metal or oxide thin films oriented for applications in the sensors for chemical and biochemical parameters.
A detailed overview of optical fibre sensors with thin film coatings on the surface is presented, followed by a description of the fundamental physical processes involved on the light transmission and modulation. Moreover, are addressed all the techniques used to fabricate the bare structures, to perform the coatings around the cylindrical single mode fibres and to perform the morphological and chemical analysis of the thin film coatings. Different applications and studies were performed considering specific sensing parameters.
The experimental results achieved includes the study of the spectral properties of long period fibre gratings coated with oxide layers such as titanium dioxide and zinc oxide. The intrinsic refractometric sensitivity is enhanced depending of the thickness and the refractive index of the oxide layer. In particular, for refractive index values of the surrounding medium higher than the fibre cladding refractive index the sensitivity could be higher than 12400 nm/RIU. The majority of edible oils have high refractive index values. Accordingly it was developed a specific sensor for monitoring the thermal deterioration of extra virgin olive oil over time and to detect contamination with organic solvents.
The spectral characteristics of one attenuation band of long period fibre gratings were studied in real time during the oxidation process of thin film metals layered on the optical fibre surface in the grating region. The monitoring of the changes of the attenuation band permits to obtain detailed information about the oxidation phase transition undertake by the metal thin films.
The detection of small concentrations of gases or vapours, which are flammable and with high explosion risk is extremely important for the safety of people and property. Looking for the detection of hydrogen and vapours, as ethanol and hexane, an investigation using fibre Bragg gratings coated with palladium and long period fibre gratings coated with layers of zinc oxide was performed.
The chemical etching process with hydrofluoric acid applied to silica based optical fibres causes a reduction in the fibre cladding diameter allowing the evanescent component of the electromagnetic field to interact with the metal coating interface leading to the generation of surface plasmons. Taper structures coated with gold and titanium dioxide, operated in reflection and in transmission modes at 1550 nm, were fabricated and characterized for the measurement of the surrounding refractive index, resulting in sensitivities above 3000 and 5000 nm/RIU, respectively, in a refractometric range that extends from 1.300 to 1.380.
The fabricated and characterized evanescent field based devices were applied to the recognition of thrombin through the functionalization of the fibre surface with a complex of poly-L-lysine and an aptamer. The high performance of sensing structures of this type operating in the surface plasmonic resonance mode permit detections of 10 nM of thrombin with resolutions down to 0.54 nM.
Notlar:
School code: 5896
Tüzel Kişi Ek Girişi:
Mevcut:*
Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(678843.1) | 678843-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
On Order
Liste seç
Bunu varsayılan liste yap.
Öğeler başarıyla eklendi
Öğeler eklenirken hata oldu. Lütfen tekrar deneyiniz.
:
Select An Item
Data usage warning: You will receive one text message for each title you selected.
Standard text messaging rates apply.