Abstract
In this work, a polymeric sensitive layer based on the acid-base equilibrium of phenol and of its derivative p-nitro-phenol is presented for carbon dioxide measurements. Thin films casted on glass slides were tested, using a LED source (lambda c at 410 nm) and an Ocean Optics USB4000 spectrometer, in the 0% to 15.25% CO2 concentrations range, showing a 40% maximum transmittance variation with a 51s response time and a 0.15% resolution. Preliminary results indicate that CO2 also induces refractive index changes in the sensitive layer. Using a fiber based interferometric setup, a CO2 dependent refractive index change of similar to 0.045 RIU was observed, in the 0%-90% CO2 concentration range.

Abstract
A fiber-optic curvature sensor based on a core offset single-mode fiber (SMF) combined with a fiber Bragg grating (FBG) is presented. The FBG cladding modes are efficiently excited by the large core misalignment. The curvature of the fiber can be obtained by the ratio between the recoupled cladding mode power and the reflected core mode power. These measurements are independent from temperature variation.

Abstract
In this work a self-referencing fiber optic intensity sensor using virtual instrumentation is presented. To ensure higher flexibility and dynamic optimization, the use of an optical fiber delay line or an electrical delay line is avoided by implementing a delay line in the virtual domain, preserving the self-referencing and sensitivity characteristics of the proposed optical intensity sensing structure. Results are presented where displacement is measured with an 18 mu m resolution demonstrating the concept feasibility.

Abstract
In this work is studied the response of optical fiber long period grating (LPG) to changes of the refractive index of the external media relatively to variations of wavelength and in transmission. The response of the LPG to refractive index greater and lesser than to cladding is investigated. A nanolayer was deposited onto the fiber to increase the sensitivity of the LPG to refractive index of the external media higher than cladding. The film modifies the rates of effective modes of cladding, thus improving the response of the changes in the refractive index of the external media higher than that in the refractive index of the cladding (n(cl) approximate to 1.457). The Langmuir-Blodgett technique was used for the deposition of the nanolayer.

Abstract
Optical coherence tomography (OCT) imaging at the 1060-nm region proved to be a successful alternative in ophthalmology not only for resolving intraretinal layers, but also for enabling sufficient penetration to monitor the subretinal vasculature in the choroid when compared to most commonly used OCT imaging systems at the 800-nm region. To encourage further clinical research at this particular wavelength, we have developed a compact fiber-optic source based on amplified spontaneous emission (ASE) centered at similar to 1060 nm with similar to 70-nm spectral bandwidth at full-width at half-maximum and output power > 20 mW. Our approach is based on a combination of slightly shifted ASE emission spectra from a combination of Neodymium- and Ytterbium-doped fibers. Spectral shaping and power optimization have been achieved using in-fiber filtering schemes. We have tested the performance of the source in an OCT system optimized for this wavelength.

Abstract
This paper presents a comparative study of the behaviour of different kinds of optical fibre sensors in response to high temperatures. It compares the performance of regenerated fibre Bragg gratings (FBGs) written in hydrogen-loaded and non-loaded fibres with long period gratings (LPGs) written through the two different processes of ultraviolet (UV) irradiation and electrical arc discharges. This work shows the importance of the use of hydrogen-loaded fibres to achieve regenerated FBGs capable of withstanding high temperatures as high as 955 degrees C. In addition, the results demonstrated that LPGs recorded by electric arc discharges have higher thermal resistance than LPGs written by UV radiation.