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About

About

Hi! I'm Daniel, one of the many people engaged in making science at INESCTEC. Our group here, the Center of Applied Photonics (CAP), is fantastic and friendship and cooperation are like a second skin for everyone.

I started my career as a university teacher in 1999 when I was invited to help as a monitor for the Department of Physics at the University of Trás-os-Montes e Alto Douro while I was finishing to graduate in electrotechnics engineering. Currently I'm an Auxiliary Professor at the same University.

I started collaborating as an investigator in 2002 when INESC accepted me in the course of my Masters as well through all the time of my PhD, both in the Department of Physics of the Faculty of Sciences of the University of Porto. Through all this years some of us were especially interested in micromachining and microfabrication. With this objective several equipment was developed, especially in the laser direct witting area where I helped both with hardware and software as well as characterizing the writing process. My research activities include hybrid sol-gel based waveguides, integrated optical sensors and laser direct writing techniques for integrated optics and microfabrication.

Interest
Topics
Details

Details

  • Name

    Daniel Alexandre
  • Role

    Senior Researcher
  • Since

    02nd January 2002
  • Nationality

    Portugal
  • Centre

    Applied Photonics
  • Contacts

    +351220402301
    daniel.alexandre@inesctec.pt
001
Publications

2021

Food Waste and Qualitative Evaluation of Menus in Public University Canteens-Challenges and Opportunities

Authors
Aires, C; Saraiva, C; Fontes, MC; Moreira, D; Moura Alves, M; Goncalves, C;

Publication
FOODS

Abstract
Background: This study aims to evaluate food waste and menu quality in two canteens (A and B) from a Portuguese public university in order to identify challenges and opportunities to improve the food service. Methods: Food waste included the analysis of two canteens over 5 consecutive days by selective aggregate weighing. A qualitative evaluation of a 5-week menu cycle related to lunches was performed through the Qualitative Evaluation of Menus (AQE-d) method. Results: Both menus have "satisfactory " evaluations and lower adequacy to the dietary guidelines in criteria A, which evaluates general items from the dish, and in criteria B, which evaluates meat, fish and eggs. The calculated mean of food waste in both canteens exceeded the acceptable limit of 10%, except for the vegetarian (7.5%) dish in canteen A. The biggest waste was found in the vegetarian dish (16.8%) in canteen A. In meat dishes the conduit presents more waste (17.0%) than in fish and vegetarian dishes. Among these, the vegetables were the most wasted (25.3% and 27.9%, respectively). Conclusion: This work presents some insights to future interventions in the direction of a healthier and more sustainable foodservice.

2019

Advances in Fs-Laser Micromachining Towards the Development of Optofluidic Devices

Authors
Maia, JM; Amorim, VA; Alexandre, D; Marques, PVS;

Publication
OPTICS, PHOTONICS AND LASER TECHNOLOGY 2017

Abstract
In this chapter the developments made in femtosecond laser micromachining for applications in the fields of optofluidics and lab-on-a-chip devices are reviewed. This technology can be applied to a wide range of materials (glasses, crystals, polymers) and relies on a non-linear absorption process that leads to a permanent alteration of the material structure. This modification can induce, for instance, a smooth variation of the refractive index or generate etching selectivity, which can be used to form integrated optical circuits and microfluidic systems, respectively. Unlike conventional techniques, fs-laser micromachining offers a way to produce high-resolution three-dimensional components and integrate them in a monolithic approach. Recent advances made in two-photon polymerization have also enabled combination of polymeric structures with microfluidic channels, which can provide additional functionalities, such as fluid transport control. In particular, here it is emphasised the integration ofmicrofluidic systems with optical layers and polymeric structures for the fabrication of miniaturized hybrid devices for chemical synthesis and biosensing.

2018

Fabrication of Monolithic Add-Drop Filters in Pure Silica by Femtosecond Laser Writing

Authors
Marques, PVS; Amorim, VA; Maia, JM; Alexandre, D; Viveiros, D;

Publication
2018 20TH ANNIVERSARY INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON)

Abstract
This paper will review the fabrication of monolithic integrated optical devices by laser direct writing with femtosecond pulsed laser sources, starting with the description of experimental procedures and optimal conditions to fabricate low loss optical waveguides, directional couplers, Y-junctions and first order Bragg gratings by point-by-point writing methods. Finally, the characterization results of a fully operational Add-Drop filter in pure fused silica substrate are described.

2017

Optimization of Broadband Y-Junction Splitters in Fused Silica by Femtosecond Laser Writing

Authors
Amorim, VA; Maia, JM; Alexandre, D; Marques, PVS;

Publication
IEEE PHOTONICS TECHNOLOGY LETTERS

Abstract
Optical Y-junction power splitters owe their inherent broadband spectral behavior to their design. However, depending on the fabrication technique employed, asymmetries in the junction might arise, perturbing its performance; this is the case in femtosecond laser written Y-junctions where one arm is typically written over the top of the other. In this letter, the spectral behavior of Y-junctions fabricated in fused silica by the femtosecond laser direct writing technique was analyzed and optimized for the first time, to the best of our knowledge. The junction arms output power balance as well as the corresponding spectral flatness between 1300 and 1600 nm is substantially increased by the implementation of an initial separation between the arms at the junction diverging point, enabling the manufacturing of balanced broadband Y-junctions.

2017

Real-Time Optical Monitoring of Etching Reaction of Microfluidic Channel Fabricated by Femtosecond Laser Direct Writing

Authors
Maia, JM; Amorim, VA; Alexandre, D; Marques, PVS;

Publication
JOURNAL OF LIGHTWAVE TECHNOLOGY

Abstract
Femtosecond laser direct writing is a three dimensional fabrication technique that can be applied to produce integrated optical components with high spatial resolution or microfluidic channels when combined with HF etching. The same fabrication technique can thus be employed to produce monolithic optofluidic devices for sensing applications. One of the most common sensing schemes involves evanescent optical interaction; therefore, the channel must meet some requirements regarding surface roughness, which will depend on the laser writing conditions, as described in this paper. However, of more significance is the distance between waveguiding medium and microfluidic channel that must be accurately defined. This control can be achieved by monitoring the etching reaction of a waveguide grating written a few microns from the channel, as introduced in this paper. In addition to its function as an etching monitor, the grating can also be used as a coarse refractive index sensor device.