Abstract
A refractive index sensor was designed using a novel approach to sensing based on a cleaved standard fiber Bragg grating (FBG) at the grating region, which enables the FBG to interact with its surrounding environment. The sliced-FBG (SFBG) exhibits a variable phase shift in the reflection response due to the length of the last grating's pitch, which differs from the rest. At the SFBG, the signal is the result of interference between the reflected wave from the grating and the transmitted spectrum returned due to Fresnel reflection at the final pitch, and the intensity of this signal depends on the refractive index of the surrounding medium. Based on this phenomenon, an intensity-based refractive index sensor with self- referencing technique was employed in this experiment, whereby the grating peak maximum point served as the signal reference, while the minimum of the Fresnel peak from each measurement functioned as the signal input. The proposed sensor demonstrated the ability to measure refractive indices within the range of 1.333-1.339, with a resolution of approximate to 10(-3), and a minimum detectable value of 6x10(-4) RIU (the data yielded a linear response with R-2=0.990). This study presents an innovative data sensing approach compared to existing techniques found in literature, which typically employ wavelength variation in the reflected wave to extract the desired information.

Abstract
This work presents an implementation of a reference optical cavity based on parasitic cavities on a low coherence interferometric system. This method allows a maximization of the number of sensors to be implemented without occupying additional reading channels.

Abstract
Raman technology offers a cutting-edge approach to measuring glucose solutions, providing precise and non-invasive analysis. By probing the vibrational energy levels of molecular bonds, Raman technology generates a unique spectral fingerprint that allows for the accurate determination of glucose concentrations. This study proposes the use of Raman spectroscopy to identify different glucose concentrations through the detection of Raman fingerprints. As expected, higher concentrations of glucose in the solution conducted to higher peak bands, indicating more glucose molecules interacting with light and consequently increasing the magnitude of inelastic scattering. This non-destructive approach preserves sample integrity and facilitates rapid analysis, making it suitable for various applications in biomedical research, pharmaceutical development, and food science.

Abstract
This work proposes a signal processing algorithm to analyse the optical signal from a Low Coherence Interferometric (LCI) system. The system uses a Mach-Zehnder (MZ) interferometer to interrogate a Fabry-Perot cavity, working as an optical sensor. This algorithm is based on the correlation and convolution operations, which allows the signal to be reconstructed based on itself, as well as, on the linearization of the signal phase, allowing the non-linearities of the actuator incorporated on the MZ interferometer to be compensated. The results show a noise reduction of 30 dB in the signal acquired. As a result, a reduction of 8.2 dB in the uncertainty of the measurement of the physical measurand is achieved. It is also demonstrated that the phase linearization made it possible to obtain a coefficient of determination (namely, R-squared) higher than 0.999.

Abstract
Optical fiber sensors were implemented to measure in-situ temperature variations in an oscillatory flow crystallizer operating in continuous. The sensors were fabricated by cleaved in the middle 8 mm-length fiber Bragg gratings, forming tips with a Bragg grating of 4 mm inscribed at the fiber ends. The geometry of the sensors fabricated, with a diameter of 125 mu m, allowed the temperature monitorization of the process flow, inside the crystallizer, at four different points: input, two intermediate points, and output. The results revealed that the proposed technology allows to perform an in-situ and in line temperature monitorization, during all the crystallization process, as an alternative to more expensive and complex technology.