Bernard Dussardier

Université Nice-Sophia Antipolis / CNRS · Laboratoire de Physique de la Matière Condensée (UMR 7336)

Gamma-ray-induced attenuation in Al-doped and Al/Tm-co-doped optical fibers is investigated in the visible and near-infrared domain up to 1 Gy. The behavior of radiation-induced attenuation (RIA) regarding dose and dose rate is discussed. Our results reveal high sensitivities for both types of fibers at low gamma ray doses and also reveal that Al/T...

Arsenic is one of the most toxic elements present in the environment, especially in water. The World Health Organization (WHO) recommends a maximum concentration of arsenic in drinkable water of 10 μg/l (10 ppb). Sensors implementing Surface Enhanced Raman Scattering (SERS) can detect chemical species at low concentrations. The aim of this study is...

We report on a mid-infrared Q-switched erbium-doped all-fiber laser using a dysprosium-doped silica fiber as saturable absorber for the first time in this wavelength range. Moreover, we demonstrate the use of a highly reflective chirped fiber Bragg grating written in a silica fiber as the input coupler for such lasers. This Q-switched all-fiber las...

Gamma-induced RIA of aluminosilicate and Al/Tm co-doped optical fibers is investigated in the visible and near-infrared domain. The data reveal a promising interrogation wavelength for low dose, highly sensitive dosimetry with Al/Tm fibers.

Media featuring both optical gain and disorder, such as random lasers, represent formidable challenges as subjects of research due to the high complexity of the light propagation within them; however, dramatic advances in this nascent field have been furnished by the paradigm of applying wavefront shaping techniques to the beam pumping the system....

Novel schemes are proposed for building an all-fiber mode-locked laser cavity operating at 2.8 microns based on a heavily erbium-doped fluoride fiber bounded by a semiconductor saturable absorber mirror and a fiber Bragg grating.

Standard MCVD process and solution doping are commonly used for processing rare-earth doped optical fibers. Since the 70's, this technique is mainly employed to fabricate homogeneous preforms in the longitudinal direction. A variant is proposed here, by using two doping solutions and by applying a gradual time doping. To demonstrate the validity of...

Photo-darkening prevents developing of new applications of rare-earth doped silica fibre lasers or amplifiers operating at wavelengths shorter than or at any wavelength at high power. The photo-darkening is characterized by a decrease of the laser intensity during amplification. In this article, we are interested in -doped fibres. This ion offers m...

This article presents a scheme for few-mode EDFA, which allows to choose independent amplification lengths for different mode groups. The EDF is a dual concentric core fiber, where the central core is connected to the line FMF and the ring core is doped with erbium to provide amplification. The modes of FMF are launched into the central core of the...

By pumping thulium-doped silica-based fibers at 1.07 μm, rapid generation of absorbing centers leads to photoinduced attenuation (PIA). This detrimental effect prevents exploiting laser emissions in the visible and near infrared. We report on the characterization of the PIA versus the fiber core composition, particularly the concentration of thuliu...

We study rare-earth-doped optical fibers under laser pumping and/or ionizing radiation conditions, and characterize the photo- and/or radio-darkening phenomena happening through processes depending on fiber composition and experimental conditions.

Optical fibers are the basis for applications that have grown considerably in recent years (telecommunications, sensors, fiber lasers, etc). Despite undeniable successes, it is necessary to develop new generations of amplifying optical fibers that will overcome some limitations typical of silica glass. In this sense, the amplifying Transparent Glas...

This article proposes an original concept of a dual-concentric-core few-mode erbium doped fiber (EDF) for amplification of the LP11 and LP21 mode groups of a few mode fiber (FMF) at 1530-nm wavelength with controlled differential modal gain (DMG). The proposed EDF consists of a central core and a ring core. The ring core is doped with Er3+ ions and...

We review our recent progress in the characterization of the embedding of rare-earth elements in nanometer-scale particles or phase-separated glassy regions within the core of silicabased optical fibres, and discuss future directions.

A fiber made by Furnace CVD was codoped with Erbium and Magnesium using a Flash Vaporization System for the first time. The fiber core is spontaneously formed as a Transparent Glass Ceramic (TGC). Due to the small nanoparticle size (<50 nm) and high volumetric density (1020-1021 m-3), the optical loss due to scattering is as low as < 0,6 dB/m. Erbi...

Nous proposons une analyse numérique d'une fibre amplifiant les groupes de modes LP 11 et LP 21 d'une fibre faiblement multimode avec un gain modal différentiel ajustable. La fibre se compose d'un coeur central et d'un coeur annulaire qui est dopé aux ions Er 3+. Les modes du coeur central de la fibre amplificatrice sont excités par les modes de la...

Silica-based fibers doped with LaF3:Tm3+ nanoparticles, prepared by MCVD and solution doping exhibited a fluorescence lifetime of 70 μs at 810 nm and 1470 nm, with background losses below 0.1 dB/m at 1300 nm.

Silica-based fibers doped with LaF 3 :Tm³⁺ nanoparticles, prepared by MCVD and solution doping exhibited a fluorescence lifetime of 70 μs at 810 and 1470 nm, with background losses below 0.1 dB/m at 1300 nm.

The study of Bismuth (Bi)-doped silica fibers has been performed by using thermally stimulated luminescence. The thermo-luminescence peaks have been spectrally resolved in order to observe the effect of co-dopants on Bi luminescence. A new peak around 625K was observed for the first time in Bi-doped Al-Ge-silicate fibers. This peak is believed to b...

Developing new rare-earth ion-doped optical fibres for power amplifiers and lasers requires continuous improvements in fibre spectroscopic properties. To overcome some limitations inherent to silica glass, it is proposed to embed rare-earth ions in dielectric nanoparticles. In this article we focus on the modifications of the Er 3+ ion spectroscopy...

Cours donné dans le cadre de l'école " du verre au cristal : nucléation et cristallisation des matériaux vitreux "

Séminaire donné au LphiA (Angers)

Rare earth (RE) doped silica-based optical fibres with transparent glass ceramic (TGC) core were fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped dielectric nanoparticles (DNP), their density and mean diameter...

We report on using nanometric mass spectroscopy and molecular dynamics modelling to characterize the composition and structure of self-grown erbium-doped nanoparticles in transparent glass ceramic optical fibres fabricated by modified chemical vapour deposition without post-ceramming.

The development of new active optical fibre devices requires materials with « augmented » intrinsic properties, though using luminescent ion (LI) –doped silica as host glass. Optical fibers containing dielectric nanoparticles (DNP) grown by phase separation are proposed. DNP would optimally fully encapsulate LI to produce « engineered » spectroscop...

Thulium-doped fibers are renowned for their applications in high power fiber lasers at around 2 μm. It is despite the low quantum conversion efficiency of 3F4 level in thulium doped silica fibers, which is about 10% compared to ~100% quantum conversion efficiency of the ytterbium- and erbium-doped fibers, at around 1 μm and 1.5 μm, respectively. Th...

Developing of new rare-earth (RE)-doped optical fibres for power amplifiers and lasers requires continuous improvements in the fibre spectroscopic properties (like shape and width of the gain curve, optical quantum efficiency, resistance to spectral hole burning and photodarkening...). Silica glass as a host material for fibres has proved to be ver...

A chromium-doped saturable absorber fibre stabilizes an otherwise spontaneously chaotic ytterbium- doped fibre laser. This original passively Q-switched all-fibre laser produces sustained and stable trains of smooth pulses at high repetition rate.

Thulium-doped fibers suitable for core-pumped single-frequency lasers were fabricated by the modified chemical vapor deposition (MCVD) method. Refractive index profile, doping profile and spectral absorption was measured. High doping concentration of thulium ions should be achieved to allow for high absorption of light at a pump wavelength while th...

Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles, their density and mean diameter in the fibe...

Experimental observation of the self-induced laser line sweeping (SLLS) in fiber ring lasers is presented. The SLLS with the same gain fiber is studied in Fabry-Perot cavity for comparison. The SLLS effect manifests itself as a laser wavelength drift with speed of the order of nanometer per second from shorter to longer wavelengths across several n...

Experimental observation of the self-induced laser line sweeping (SLLS) in fiber ring lasers is presented. The SLLS with the same gain fiber is studied in Fabry-Perot cavity for comparison. The SLLS effect manifests itself as a laser wavelength drift with speed of the order of nanometer per second from shorter to longer wavelengths across several n...

Rare-earth doped fiber lasers are subject to instabilities and various self-pulsed regimes that can lead to catastrophic damage of their components. An interesting self-pulsing regime accompanied with laser wavelength drift with time is the so called self-induced laser line sweeping (SLLS). Despite the early observations of the SLLS in solid-state...

The chapter is situated in the fields of fiber materials sciences and technologies (particularly dealing with the fiber glass compositions and luminescent ion doping, and transparent glass ceramic optical fibers), and applications such as fiber lasers and amplifiers. We propose to present a review of research activities on rare-earth (RE) and trans...

The development of new active optical fibre devices requires materials with « augmented » intrinsic properties, though using luminescent ion (LI) –doped silica as host glass. Optical fibers containing dielectric nanoparticles (DNP) grown by phase separation are proposed. DNP would optimally fully encapsulate LI to produce « engineered » spectroscop...

The fabrication of Er-doped ZrO2-based nanocrystalline phase-separated silica optical preforms by the MCVD and solution doping techniques is presented. Fabricated preform cores are nearly transparent and contain phase-separated rare-earth doped nanocrystalline particles with diameters mainly in a range from 20 to 80 nm. High concentrations of erbiu...

A chromium-doped saturable absorber fiber stabilizes an otherwise spontaneously chaotically self-pulsing ytterbium-doped fiber laser . This original passively Q-switched all-fiber laser produces sustained and relatively stable trains of smooth pulses at high repetition rate.

Rare earth (RE)-doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of postceramming. The main characteristics of the RE-doped oxide nanoparticles namely, their density and mean diameter in th...

A large-mode-area single-mode optical fiber based on leaky-mode filtering was prepared by a modified chemical vapor deposition (MCVD) technique. The fiber has a leaky cladding that discriminates the fundamental mode from higher-order modes. A preliminary version has a 25 μm core diameter and 0.11 numerical aperture. A Gaussian-like mode with 22 μm...

A spontaneously chaotic, self-pulsing ytterbium-doped fibre laser is partially stabilized into the passively Q-switched mode of operation using a chromium-doped saturable absorber fibre. This original all-fibre laser produces sustained and stable trains of smooth pulses at high repetition rate.

In rare-earth-doped silica optical fibres, the homogeneous distribution of amplifying ions and part of their spectroscopic properties are usually improved by adding selected elements, such as phosphorus or aluminum, as structural modifier. In erbium ion (Er3+) doped fibres, phosphorus preferentially coordinates to Er3+ ions to form regular cages ar...

A large mode area single-mode optical fibre based on leaky mode filtering was prepared by MCVD. The cladding structure discriminates the fundamental mode from the higher order ones. A preliminary version has 25-$\mu$m core diameter and 0.11 numerical aperture. A Gaussian-like mode with 22-$\mu$m MFD is observed after 3-m propagation, in agreement w...

A compact upconversion fiber laser operating around 810 nm is proposed using thulium-doped silica-based fiber with locally modified thulium environment by high alumina codoping. Using a comprehensive numerical model of thulium doped fiber we investigate performance of the proposed laser. Comparison with two other thulium hosts, fluoride glass and s...

An efficient method to fabricate transparent glass ceramic fibers containing in-situ grown Er3+-doped oxide nanoparticles is presented. Characterization of the drawn fibers exhibits low loss (0.4 dB/m) and broadened Er3+ emission spectrum. This attractive method offers new scopes for fiber amplifiers.

A novel approach for controlling and flattening the radial distribution of the erbium ions within an aluminium enriched silica core glass as part of the modified chemical vapour deposition and solution doping techniques is presented.

Silica-based thulium-doped fiber devices operating around 810 nm would extend the spectral range covered by highpower fiber devices. Using a comprehensive numerical model of the fiber we have shown that efficient lasing at 810 nm can be achieved for specific ranges of the laser cavity parameters in silica-based thulium-doped fibers with enhanced <s...

Silica-based thulium-doped fiber devices operating around 810 nm would extend the spectral range covered by high- power fiber devices. Using a comprehensive numerical model of the fiber we have shown that efficient lasing at 810 nm can be achieved for specific ranges of the laser cavity parameters in silica-based thulium-doped fibers with enhanced...

Le développement de nouvelles fibres optiques amplificatrices nécessite de s'affranchir des limitations spectroscopiques imposées par la silice. Pour cela, nous avons choisi d'encapsuler les ions luminescents dans des nano-particules d'oxyde. Elles sont obtenues par séparation de phase déclenchée par des cycles thermiques nécessaires a la réalisation...

Ce travail démontre l'intérêt de la thermoluminescence, une technique particulièrement adaptée à la caractérisation des défauts et centres ionisés par les radiations dans des préformes de fibres optiques en silice dopées ytterbium. Le rôle des ions Yb3+ dans l'absorption des radiations et celui des porteurs délocalisés par photo-ionisation dans l'a...

Radiation effects in ytterbium-doped silica optical fibers are still poorly studied despite their importance in space-based applications as optical inter-satellite links. We investigate such effects by coupling thermally stimulated luminescence and optical absorption measurements. Connections between traps populated by X ray irradiations and the ra...

Most exploited operating wavelengths offered by rare-earth doped fiber lasers are situated around 1, 1.5 and 2 µm. In this paper we investigate thulium-doped fiber (TDF) laser operating around 800 nm that would extend the spectral range already covered by high-power fiber lasers. The single-transverse mode, high-power laser source in the 800 nm spe...

Optical fibres are mostly based on silica glass for its interesting properties (reliability, low cost, ...). However, some of its characteristics (high phonon energy, low solubility of luminescent ions, ...) induce drawbacks in spectroscopic properties of rare-earth (RE)-doped fibre lasers and amplifiers. Here we investigate the growing of RE-doped...

The presence of scatterers, for long, had been considered detrimental for the growth of photonic devices. Hence, a great care is taken during the fabrication of fibers and optical devices to avoid scatterers, which may lead to a loss of signal strength and efficiency of the device. However, random scatterers have become a topic of immense research...

We analyse a multilayer leaky cladding (MLC) fibre using the finite element method and study the effect of the MLC on the bending loss and birefringence of two types of structures: (i) a circular core large-mode-area structure and (ii) an elliptical-small-core structure. In a large-mode-area structure, we verify that the multilayer leaky cladding s...

We present a co-axial dual-core resonant leaky optical fibre design, in which the outer core is made highly leaky. A suitable choice of parameters can enable us to resonantly couple power from the inner core to the outer core. In a large-core fibre, such a resonant coupling can considerably increase the differential leakage loss between the fundame...

Selection of operating wavelength of the Yb-doped fiber-ring lasers using longperiod fiber gratings (LPFGs) is suggested. In the proposed method, customized LPFG that sustains high powers serves as a broad-band rejection filter. It modifies the net gain profile of the laser, enabling the peak gain to occur at a designed wavelength. Spectral range o...

We report design and subsequent fabrication of an intrinsically gain flattened Erbium doped fiber amplifier (EDFA) based on a highly asymmetrical and concentric dual-core fiber, inner core of which was only partially doped. Phase-resonant optical coupling between the two cores was so tailored through optimization of its refractive index profile par...

We present some of our research activities dedicated to doped silica-based optical fibers, aiming at understanding the spectral properties of luminescent ions, such as rare-earth and transition metal elements. The influence of the local environment on dopants is extensively studied: energy transfer mechanisms between rare-earth ions, control of the...

Erbium doped materials are of great interest in optical telecommunications due to the Er3+ intra-4f emission at 1.54 ?m. Erbium doped fibre amplifiers (EDFA) were developed in silica glass because of the low losses at this wavelength and the reliability of this glass. Developments of new rare earth doped fibre amplifiers aim to control their spectr...

The development of materials for optical signal processing represents a major issue in present technology. In this contribution we present a study on Er-doped fiber preforms where particular attention is devoted on how the addition of CaO in the glass modifies the local environment of the rare earth. The results from photoluminescence and Extended...

A new route was recently proposed to modify some spectroscopic properties of rare-earth ions in silica-based fibers. We had shown the incorporation of erbium ions in amorphous dielectric nanoparticles, grown in fiber preforms. Here we present the achieved stabilization of nanometric erbium-doped dielectric nanoparticles within the core of silica fi...

Cladding-pumped ytterbium-doped fiber lasers belong presently among the most attractive high-power laser sources for wavelengths around 1060 nm. While the most typical configuration of the fiber laser cavity is linear Fabry-Perot arrangement with fiber Bragg gratings (FBGs), for some applications the ring cavity is preferable as it offers higher st...

Silica-based thulium-doped fibers sensitized by ytterbium are being developed for applications in fiber amplifiers and lasers at various wavelengths (around 800 nm, 1470 nm and 2 µm). Several studies have been performed to design and optimize thulium-and ytterbium-doped fiber (TYDF) amplifiers and lasers at the above mentioned wavelengths. Although...

A high sensitive temperature sensor based on evanescent field coupling between a side-polished fiber half-coupler (SPFHC) and a thermo-optic multimode overlay waveguide (MMOW) is designed and demonstrated. Such a structure essentially functions as an asymmetric directional coupler with a band-stop characteristic attributable to the wavelength-depen...

To improve spectral gain properties of silica-based EDFA, we propose a new route by embedding Er ions into dielectric nanoparticles. Broadening of emission band and fibre characterizations are presented.