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Publicações

Publicações por CAP

2017

Embedded Fabry-Perot based Sensor Using Three-Dimensional Printing Technology

Autores
Monteiro, CS; Santos, BF; Silva, SO; Abreu, P; Restivo, MT; Frazao, O;

Publicação
2017 25TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS (OFS)

Abstract
A sensor based on Fabry-Perot interferometry with a hollow microsphere cavity embedded in a 3D printed structure is proposed. The sensor was tested for lateral loading and temperature, showing promising results. By imprintring the sensor on the structure, the dynamic range of application is severely increased enabling the application of the sensor in harsh environments.

2017

Fabry-Perot Sensor based on Two Coupled Microspheres for Strain Measurement

Autores
Monteiro, CS; Kobelke, J; Schuster, K; Bierlich, J; Frazao, O;

Publicação
2017 25TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS (OFS)

Abstract
A Fabry-Perot based sensor with two coupled hollow microspheres is presented. The sensor was fabricated using fusion splicing techniques, enabling a low-cost, highly reproducible, production. The coupling of the two microspheres gives rise to a highly sensitive strain sensor, reaching a sensitivity of 4.07 pm/mu epsilon. The allsilica composition leads to a low thermal sensitivity, making the proposed structure suitable applications in environments with varying external conditions.

2017

Microfiber Knot Resonators as Sensors A Review

Autores
Gomes, AD; Frazao, O;

Publicação
PROCEEDINGS OF THE 5TH INTERNATIONAL CONFERENCE ON PHOTONICS, OPTICS AND LASER TECHNOLOGY (PHOTOPTICS)

Abstract
Microfiber knot resonators find application in many different fields of action, of which an important one is the optical sensing. The large evanescent field of light can interact and sense the external medium, tuning the resonance conditions of the structure. The resonant property of microfiber knot resonators can also provide, in some cases, an enhancement in the sensing capability. Until nowadays, a wide variety of physical and chemical parameters have been possible to measure with this device. New developments and improvements are still being done in this field. A review on microfiber knot resonators as sensors is presented, with particular emphasis on their application as temperature and refractive index sensors. The properties of these structures are analyzed and different assembling configurations are presented. Important aspects in terms of the sensor stability are discussed, as well as alternatives to increase the sensor robustness. In terms of new advances, an overview on coated microfiber knot resonators is also presented. Finally, other microfiber knot configurations are explored and discussed.

2017

Polymer and tapered silica fiber connection for polymer fiber sensor application

Autores
Ferreira, MFS; Gomes, AD; Kowal, D; Statkiewicz Barabach, G; Mergo, P; Frazao, O;

Publicação
THIRD INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
A new type of polymer and silica connection is proposed. A tapered SMF- 28 silica optical fiber tip is fabricated using a CO2 laser by focusing and stretching the fiber. The tapered silica tip is inserted in one of the holes of a microstructured polymer optical fiber using a 3D alignment system. Using a supercontinuum source, the spectrum is observed after one and after two connections. The polymer fiber is characterized in curvature while using the previous connection.

2017

Strain sensor based on hollow microsphere Fabry-Perot cavity

Autores
Monteiro, CS; Silva, SO; Frazao, O;

Publicação
THIRD INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
Fusion splicing technique was explored for the fabrication of two sensing structures based on hollow microsphere Fabry-Perot cavity. The first sensor proposed was fabricated with a hollow microsphere tip, working as a probe sensor. This structure was studied for lateral load pressure, yielding a 1.56 +/- 0.01 nm/N sensitivity. The second sensing structure relied on an in-line hollow microsphere, which allowed the detection of lateral load, with a sensitivity of 2.62 +/- 0.02 nm/N. Furthermore, the proposed structure enabled strain sensing, with a sensitivity of 4.66 +/- 0.03 pm/mu epsilon. The two sensing structures were subjected to temperature, presenting low thermal cross-sensitivity.

2017

Analysis of Signal Saturation in a Fiber Ring Resonator integrating an Intensity Sensor

Autores
Magalhaes, R; Silva, SO; Frazao, O;

Publicação
2017 25TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS (OFS)

Abstract
The proposed technique consists in an optical fiber resonator interrogated for sensor characterization, implementing an alternative technique for dynamic range improvement. Such technique relies on the analysis of an added-signal caused by signal saturation, which occurs due to the broadening of the laser pulse. A wide study for different pulse widths is presented in this work, namely for 100 ns, 5 mu s and 20 mu s, being the last one related to the emergence of an added-signal for the proposed configuration. The behavior of the waveform in the presence of an intensity sensor is also characterized.

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