Publications de Georgios Violakis

Monitoring of Torque Induced Strain in Composite Shafts with Embedded and Surface-Mounted Optical Fiber Bragg Gratings

John Botsis, Georgios Violakis, Georgios Pappas

In this study, silica glass, optical fiber Bragg gratings (FBGs) are used for torque-induced strain monitoring in carbon fiber reinforced polymer (CFRP) hollow shafts toward the development of a methodology for structural load monitoring. Optical fibers wi ...

2021

Microfabrication of curved sidewall grooves using scanning nanosecond excimer laser ablation

Patrik Willi Hoffmann, André Gabriel Kostro, Jing Gong, Josef Andreas Schuler, Georgios Violakis

Novel glazing with embedded micro-mirrors can significantly reduce the energy consumption due to cooling and lighting in buildings. Especially promising are large arrays of periodic micro compound-parabolic-concentrators (CPCs) with angular-selected transm ...

SPIE2018

An experimental-numerical investigation of hydrothermal response in adhesively bonded composite structures

John Botsis, Véronique Michaud, Hans Georg Limberger, Roohollah Sarfaraz Khabbaz, Georgios Violakis, Luis Pablo Canal Casado

Water absorption and thermal response of adhesive composite joints were investigated by measurements and numerical simulations. Water diffusivity, saturation, swelling, and thermal expansion of the constituent materials and the joint were obtained from gra ...

Elsevier2015

Monitoring strain gradients in adhesive composite joints by embedded fiber Bragg grating sensors

John Botsis, Véronique Michaud, Hans Georg Limberger, Roohollah Sarfaraz Khabbaz, Georgios Violakis, Luis Pablo Canal Casado

The adhesive bonding of composite materials can be applied to assemble light-weight structures for aeronautical applications. However, the application of adhesive bonds in primary load-bearing structures is limited by the lack of adequate techniques to mon ...

Elsevier2014

Annealing of UV Ar+ and ArF excimer laser fabricated Bragg gratings: SMF-28e fiber

Hans Georg Limberger, Georgios Violakis

Fiber Bragg gratings fabricated in pristine SMF-28e fibers using pulsed ArF-excimer and cw 244-nm Ar+ laser were annealed using tempering rates from 0.0038 to 0.25 K/s. Demarcation energy mapping allowed for the determination of the frequency factors and t ...

Optical Society of America2014

Stability of Fiber Bragg Gratings Fabricated Using UV Ar+ and ArF Excimer in Bismuth-Aluminum-co-Doped Silica Fibers

Hans Georg Limberger, Georgios Violakis

Continuous annealing of fiber Bragg gratings fabricated using cw and pulsed laser irradiation in Bi-Al-co-doped fibers of different concentrations show activation energy spectra linked to Bi-Al. Thermal stability maps were obtained by their analytical repr ...

2014

Monitoring strain gradients in adhesive composite joints by embedding fibre Bragg grating sensors

Véronique Michaud, John Botsis, Hans Georg Limberger, Georgios Violakis, Behzad Dehghan Manshadi, Luis Pablo Canal Casado

2013

Dose dependence of luminescence increase in H2-loaded Bi-Al co-doped optical fibers by cw 244-nm and pulsed 193-nm laser irradiation

Hans Georg Limberger, Georgios Violakis

The near infrared luminescence is increased in H2-loaded Bi-Al co-doped optical fibers by irradiation of cw 244-nm or pulsed 193-nm laser light. The dose dependence is different for the two lasers. ...

Ieee2013

UV-induced luminescence and photosensitivity in bismuth-aluminum doped optical fibers

Georgios Violakis

EPFL2013

Photosensitivity and Luminescence Induced by ArF-Irradiation of Hydrogen Loaded Bi-SiO2 Fiber

Hans Georg Limberger, Georgios Violakis

Bi:SiO2 fiber drawn under oxidizing conditions shows ultra-low photosensitivity and no NIR luminescence under 1064 nm pumping. Hydrogen loading followed by ArF irradiation induced both. The increase of photosensitivity and the creation of luminescence cent ...

2013