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Publications

Publications by Ariel Guerreiro

2016

Compact solutions for optical fiber tweezers using Fresnel Zone and Phase Lenses fabricated using FIB milling

Authors
Rodrigues Ribeiro, RSR; Dahal, P; Guerreiro, A; Jorge, PAS; Viegas, J;

Publication
COMPLEX LIGHT AND OPTICAL FORCES X

Abstract
In this work FZL and FPL fabricated using Focused Ion Beam milling on the top of custom-made optical fibers are presented. Primary, single mode fibers are spliced to a segment of multimode fiber allowing to expand the core region. Subsequently, FZL and FPL with several focusing distances are milled on the top of the fibers. In this regard, the zone and phase plates offer distinct focusing characteristics which are here presented and analyzed. Moreover, the output optical intensity field of the FPL and FZP are evaluated and validated using an implementation of the Finite Differences Time Domain (Lumerical). Lastly, some considerations on the use of the tips as fiber optical tweezers are given.

2016

Generation of Laguerre Gaussian beams using spiral phase diffractive elements fabricated on optical fiber tips using focused ion beam milling

Authors
Rodrigues Ribeiro, RSR; Dahal, P; Guerreiro, A; Jorge, PAS; Viegas, J;

Publication
COMPLEX LIGHT AND OPTICAL FORCES X

Abstract
In this work, spiral phase lenses fabricated on the tip of single mode optical fibers are reported. This allows tailoring the fundamental guided mode, a Gaussian beam, into a Laguerre - Gaussian profile without using additional optical elements. The lenses are fabricated using Focused Ion Beam milling, enabling high resolution in the manufacturing process. The phase profiles are evaluated and validated using an implementation of the Finite Differences Time Domain. The output optical intensity profiles matching the numerical simulations are presented and analyzed. Finally, results on cell trapping and manipulation are briefly described.

2016

Hydrogen sensing via anomalous optical absorption of palladium-based metamaterials

Authors
Hierro Rodriguez, A; Leite, IT; Rocha Rodrigues, P; Fernandes, P; Araujo, JP; Jorge, PAS; Santos, JL; Teixeira, JM; Guerreiro, A;

Publication
NANOTECHNOLOGY

Abstract
A palladium (Pd)-based optical metamaterial has been designed, fabricated and characterized for its application in hydrogen sensing. The metamaterial can replace Pd thin films in optical transmission schemes for sensing with performances far superior to those of conventional sensors. This artificial material consists of a palladium-alumina metamaterial fabricated using inexpensive and industrial-friendly bottom-up techniques. During the exposure to hydrogen, the system exhibits anomalous optical absorption when compared to the well-known response of Pd thin films, this phenomenon being the key factor for the sensor sensitivity. The exposure to hydrogen produces a large variation in the light transmission through the metamembrane (more than 30% with 4% in volume hydrogen-nitrogen gas mixture at room temperature and atmospheric pressure), thus avoiding the need for sophisticated optical detection systems. An optical homogenization model is proposed to explain the metamaterial response. These results contribute to the development of reliable and low-cost hydrogen sensors with potential applications in the hydrogen economy and industrial processes to name a few, and also open the door to optically study the hydrogen diffusion processes in Pd nanostructures.

2015

Modal Filtering for Optimized Surface Plasmon Resonance Sensing in Multimode Plastic Optical Fibers

Authors
Cennamo, N; Coelho, L; Santos, DF; Baptista, JM; Guerreiro, A; Jorge, PAS; Zeni, LG;

Publication
IEEE SENSORS JOURNAL

Abstract
In this paper, we present the numerical and the experimental results of a new low cost surface plasmon resonance sensor configuration. It is based on a plasmonic sensor platform and an efficient higher order modes filtering in plastic multimode fibers, exploiting a tapered plastic optical fiber at the output of the sensor system. The experimental results have demonstrated that the tapered filter positioned after the sensor system improves the performances in terms of refractive index range and depth of the resonance curve. The results are in agreement with the numerical simulations.

2015

New SPR PCF D-type optical fiber sensor configuration for refractive index measurement

Authors
Santos, DF; Guerreiro, A; Baptista, JM;

Publication
24TH INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS

Abstract
This paper presents the performance analysis of a new geometry sensing configuration for refractive index, based on surface plasmon resonance (SPR) in photonic crystal fiber (PCF) D-type optical fiber with a thin gold layer, using the finite element method (FEM). The configuration is analyzed in terms of the loss. The results are compared with a conventional SPR D-type and with a PCF D-type optical fiber sensor for refractive index measurement. The simulation results show an improvement of the sensitivity and resolution (3.70x10(3)nm/RIU and 2.72x10(-5)RIU, respectively, when considering an accurately spectral variation detection of 0.1nm).

2015

New Trends on Optical Fiber Tweezers

Authors
Rodrigues Ribeiro, RSR; Soppera, O; Oliva, AG; Guerreiro, A; Jorge, PAS;

Publication
JOURNAL OF LIGHTWAVE TECHNOLOGY

Abstract
In the last few decades, optical trapping has played an unique role concerning contactless trapping and manipulation of biological specimens. More recently, optical fiber tweezers (OFTs) are emerging as a desirable alternative to bulk optical systems. In this paper, an overview of the state of the art of OFTs is presented, focusing on the main fabrication methods, their features and main achievements. In addition, new OFTs fabricated by guided wave photo polymerization are reported. Their theoretical and experimental characterization is given and results demonstrating its application in the manipulation of yeast cells and the organelles of plant cells are presented.

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