Open Access
Multiplexing optical fiber Fabry-Perot interferometers based on air-microcavities
(SPIE, 2019) Pérez Herrera, Rosa Ana; Novais, Susana; Bravo Acha, Mikel; Leandro González, Daniel; Silva, Susana; Frazão, Orlando; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In this work we demonstrate the multiplexing capability of new optical fiber Fabry-Perot interferometers based on airmicrocavities using a commercial FBG interrogator. Three optimized air-microcavity interferometer sensors have been multiplexed in a single network and have been monitored using the commercial FBGs interrogator in combination with FFT calculations. Results show a sensitivity of 2.18 π rad/mε and a crosstalk-free operation.
Open Access
Measurement of paracetamol concentration using an erbium-doped fiber ring cavity
(MDPI, 2023) Soares, Liliana; Pérez Herrera, Rosa Ana; Novais, Susana; Ferreira, António; Silva, Susana; Frazão, Orlando; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Process Analytical Technology (PAT) has been increasingly used in the pharmaceutical industry to monitor essential parameters in real-time during pharmaceutical processes. The concentration of Active Pharmaceutical Ingredients (APIs), such as paracetamol, is one of these parameters, and controlling its variations allows for optimization of the production process. In this study, a refractometric sensor, implemented by an interrogation system based on an Erbium-Doped Fiber Ring Cavity (EDFRC), was presented and experimentally demonstrated. The Cavity Ring proposed included a 1 × 3 coupler. One port of the coupler was used to increase the optical power of the system through a Fiber Bragg Grating (FBG), and the other two ports were used as sensing head and reference. The sensor detected variations of paracetamol concentration with a sensitivity of [(−1.00 ± 0.05) × 10−3] nW/(g/kg) and a resolution of 5.53 g/kg. The results demonstrate the potential of this technology as a possible non-invasive PAT tool.
Open Access
Measurement of paracetamol concentration using a fiber laser system
(IEEE, 2023) Soares, Liliana; Pérez Herrera, Rosa Ana; Novais, Susana; Ferreira, António; Frazão, Orlando; Silva, Susana; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A linear fiber laser system for measurements of paracetamol concentration is experimentally demonstrated. The cavity is based on a fiber loop mirror and an FBG centered at 1567.8 nm. The sensing head corresponds to a refractometric sensor, whose which principle of operation is based on Fresnel reflection in the fiber tip (FBG side). The system works at detected variations of paracetamol concentrations with a sensitivity of [8.74± 0.34)× 10-5] µW/(g/kg) and a resolution of 2.77 g/kg. The results prove that the fiber laser system could be an asset for processing industries, specifically for non-invasive and real-time measurements of concentration.
Open Access
Multiparameter sensor based on a multiinterferometric serial configuration for temperature and strain measurements
(IEEE, 2021) Pérez Herrera, Rosa Ana; Bravo Acha, Mikel; Leandro González, Daniel; Novais, Susana; Pradas Martínez, Javier; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this work, a multi-parameter point sensor based on the combination of Fabry-Perot (FP) and the anti-resonant (AR) reflecting guidance in cascade configuration is proposed and experimentally demonstrated. This structure, based on FP interference and AR reflecting guidance, was fabricated with two different air micro-cavities. The attained experimental results showed different strain and temperature sensitivities for the antiresonance contribution. However, when analyzing the FP interference, only strain sensitivity was observed, demonstrating that this air micro-cavity was also insensitive to temperature variations.
Open Access
Erbium-doped fiber ring cavity for the measurement of refractive index variations
(SPIE, 2023) Pérez Herrera, Rosa Ana; Soares, Liliana; Novais, Susana; Frazão, Orlando; Silva, Susana; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this work, an erbium-doped fiber ring cavity based on a 3dB optical coupler for refractive index measurements is presented and experimentally verified. This interrogation system, based on a 1 x 2 optical coupler, uses one of these output ports to increase the reflected optical power by means of a fiber Bragg Grating (FBG), used as a reflector. Moreover, the other output port is used as a refractive index sensing head. A spectral analysis of this interrogator system as well as a fiber cavity ring refractive index sensor characterization are carried out. Finally, an experimental comparison of the refractive index sensor range when the 3dB coupler is replace by a 1x3 one is also presented.
Open Access
Linear fiber laser configurations for optical concentration sensing in liquid solutions
(MDPI, 2024) Soares, Liliana; Pérez Herrera, Rosa Ana; Novais, Susana; Ferreira, António; Silva, Susana; Frazão, Orlando; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
In this study, different configurations based on linear fiber lasers were proposed and experimentally demonstrated to measure the concentration of liquid solutions. Samples of paracetamol liquid solutions with different concentrations, in the range from 52.61 to 201.33 g/kg, were used as a case-study. The optical gain was provided by a commercial bidirectional Erbium-Doped Fiber Amplifier (EDFA) and the linear cavity was obtained using two commercial Fiber Bragg Gratings (FBGs). The main difference of each configuration was the coupling ratio of the optical coupler used to extract the system signal. The sensing head corresponded to a Single-Mode Fiber (SMF) tip that worked as an intensity sensor. The results reveal that, despite the optical coupler used (50:50, 60:40, 70:30 or 80:20), all the configurations reached the laser condition, however, the concentration sensing was only possible using a laser drive current near to the threshold value. The configurations using a 70:30 and an 80:20 optical coupler allowed paracetamol concentration measurements with a higher sensitivity of (−3.00 ± 0.24) pW/(g/kg) to be performed. In terms of resolution, the highest value obtained was 1.75 g/kg, when it was extracted at 20% of the output power to the linear cavity fiber laser configuration.
Open Access
Paracetamol concentration-sensing scheme based on a linear cavity fiber laser configuration
(Elsevier, 2023) Soares, Liliana; Pérez Herrera, Rosa Ana; Novais, Susana; Ferreira, António; Frazão, Orlando; Silva, Susana; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A paracetamol concentration-sensing scheme based on a linear cavity fiber laser configuration is demonstrated experimentally. The laser cavity has a fiber sensor at one end, that allows refractive index measurements. The refractometer consists of a cleaved fiber tip combined with an FBG functioning as a reflecting mirror. The combination of a fiber loop mirror at the other end allows to reflect all the light from the FBG and refractometer, forming a linear cavity. By measuring the intensity variation of the Fresnel reflection at the fiber-to-liquid interface, the measured concentration is linear and have a concentration sensitivity of -8.74±0.34×10-5 µW/(g/kg), over a range of 52.61 to 219.25 g/kg, and with a resolution of 2.77 g/kg. The results obtained present high stability and prove the potential of the fiber laser system to performed real-time measurements of concentration, in a non-invasive way.