OSENS 2017 Abstracts

Short Papers
Paper Nr: 1

Recent Advances in Fiber Cavity Ring-down Technology


Susana Silva and Orlando Frazao

Abstract: A brief review in the fibre cavity ring-down (CRD) technique is presented. It addresses the latest developments in CRD technique for sensing applications, undergone at INESC TEC. The CRD is based on the conventional configuration with the possibility of adding amplification in order to compensate the output signal losses induced by the sensing head. The results obtained for strain, curvature and refractive index sensing are presented, corresponding to distinct sensing structures, namely, a chirped fibre Bragg grating (FBG), a long period grating (LPG) and a multimode interference (MMI) based sensor.

Paper Nr: 3

Microfiber Knot Resonators as Sensors - A Review


André Gomes and Orlando Frazão

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.

Paper Nr: 4

Optical Structure with PDMS Microfibre for Displacement Measurement


Daniel Kacik and Ivan Martincek

Abstract: We proposed, prepared and demonstrated an optical structure consists of conventional single-mode optical fibres and a bend PDMS microfiber. The structure forms Mach-Zehnder interferometer with variable length of an air arm. The structure can be used for sensing of various physical quantities as temperature, humidity, volatile organic compounds, etc. We demonstrated its usage by displacement measurement. For determination of a displacement we used a change of interference pattern period. The sensitivity of proposed structure is 0.027 nm/µn.