Publications de Yves Bellouard

On the Use of UV Femtosecond Pulses to Write Waveguides in Fused Silica

Ultraviolet (UV) pulses at 450 fs are a powerful tool for femtosecond laser waveguide writing in fused silica. Whereas typically sub-200 fs pulses at a high exposure dose were required, UV light efficiently creates waveguides with propagation losses below ...

IEEE2025

Sub-wavelength femtosecond laser based nanostructuring of complex patterns in the bulk of fused silica

Yves Bellouard, Pieter Vlugter

Laser-inscribing arbitrary patterns with a sub-wavelength resolution in the bulk of transparent materials is of great importance for enabling reliable and versatile nano-manufacturing. Here, we propose a seeding-writing near-field enhancement based method ...

Optica Publishing Group2025

High-speed femtosecond UV laser writing of low-loss waveguides in fused silica

Yves Bellouard, Benedikt Hermann

We demonstrate ultra-low-loss femtosecond laser-written waveguides in fused silica using 450 fs ultraviolet pulses from a frequency-tripled ytterbium laser. This favorable regime only appears at a low pulse density, enabling a two orders of magnitude faste ...

Optica Publishing Group2025

Glass multifocal microlens array through laser-induced topological transformation

Yves Bellouard, Samuel Youcef Benketaf

We investigate the use of laser-induced topological transformation for manufacturing multifocal lens arrays with arbitrary focal ranges. Cylindrical preforms manufactured by femtosecond laser and chemical etching are topologically transformed into plano-co ...

Optica Publishing Group2025

Sub-micron elastic properties measurement of single laser-affected volume in fused silica

Yves Bellouard, Arunkrishnan Radhakrishnan

Non-ablative femtosecond laser exposure of transparent substrates leads to bulk volumetric changes, and consequently, localized structural changes resulting in micron-scale variation of elastic properties in the material. Here, we demonstrate the use of gr ...

2025

Self-organised UV Femtosecond Laser Induced Modifications in the Bulk of Fused Silica

Yves Bellouard

By focusing a femtosecond laser beam in the bulk of a transparent material one can locally change the physical properties of the material itself. The interaction between NIR pulses and fused silica has been extensively studied in the past, showing how vari ...

IEEE2025

Survival of nanogratings in high melting oxide glasses upon thermal annealing

Yves Bellouard, Gözden Torun

Nanogratings were fabricated using a fs-laser inside more than 20 oxide glasses. Glass viscosity mostly dictates their thermal stability but deviation from this trend was observed in glasses containing large amount of Al2O3 or ZrO2. ...

Optical Society of America2024

Femtosecond Laser Based Nanostructuring in the Bulk of Fused Silica

Yves Bellouard, Pieter Vlugter

We develop a femtosecond laser based fabrication technique which exploits near-field enhancement to generate selectively etchable arbitrarily long nanoplanes in the bulk of fused silica. The nanoplanes volumetric morphology and formation mechanism are inve ...

Institute of Electrical and Electronics Engineers Inc.2024

Substrate comprising slots for holding optical components of a laser cavity

Yves Bellouard, Antoine Maxime Delgoffe, Saood Ibni Nazir

In a substrate (1) for holding a multitude of components (6.1, 6.2, 6.3, 6.4, 6.5, 6.6) of an optical laser cavity, wherein the substrate (1) comprises a multitude of slots (2.1, 2.2, 2.3, 2.4, 2.5, 2.6), wherein each slot (2.1, 2.2, 2.3, 2.4, 2.5, 2.6) is ...

2024

Femtosecond-laser direct-write photoconductive patterns on tellurite glass

Yves Bellouard, Gözden Torun, Anastasia Romashkina

We report the formation of arbitrary photoconductive patterns made of tellurium (Te) nanocrystals by exposing a tellurite (TeO2-based) glass to femtosecond laser pulses. During this process, Te/TeO2-glass nanocomposite interfaces with photoconductive prope ...

American Physical Society (APS)2024

On the correlation between femtosecond laser-induced defects taxonomy and localized accelerated chemical etching in fused silica

Yves Bellouard, Vinod Parmar

The non-ablative interaction of femtosecond laser pulses with fused silica leads to defects creation in the silica glass network. Here, we report on the correlation between defects and localized accelerated etching, that enables three-dimensional manufactu ...

Institute of Electrical and Electronics Engineers Inc.2024

Influence of ionization and cumulative effects on laser-induced crystallization in multilayer dielectrics

Yves Bellouard, Ruben Ricca, Victor Carle Adrien Boureau

Crystallization of amorphous layers has been demonstrated under various radically different laser-exposure conditions, including continuous wave (cw) and pulsed lasers. Here, we investigate the specific role of ionization in the crystallization of dielectr ...

2024

High-magnification observation of flow and solidification processes of laser-melted metals in microchannels

Yves Bellouard

Japan Society of Mechanical Engineers2024

Wide-Field Polarimetric Second-Harmonic Imaging for Rapid and Nondestructive Investigation of Laser-Induced Crystallization Phenomena

Yves Bellouard, Seonwoo Lee

The selective and controlled formation of nanocrystals in glass is emerging as a versatile method to achieve functional photonics, optoelectronics, and quantum devices, such as single-photon emitters. Here, we investigate the use of wide-field polarimetric ...

American Chemical Society (ACS)2024

Single-Layer Subwavelength Femtosecond-Laser-Induced Confined Nanocrystallization in Multistack Dielectrics

Yves Bellouard, Ruben Ricca

We demonstrate extreme laser-induced modification confinement in a stack of dielectric layers, along the optical axis, without the use of tight focusing. Specifically, we show that an aperiodic distribution of layer thicknesses can effectively lead to the ...

American Physical Society (APS)2023

Non-volatile data storage medium and system

Martin Vetterli, Yves Bellouard, Ruben Ricca

A data storage medium (2) comprising a stacked plurality of layers (9), each layer composed of a layer material selected from a group comprising at least two different dielectric materials, adjacent layers being formed of different materials, and at least ...

2023

Third-harmonic generation monitoring of femtosecond-laser-induced in-volume functional modifications

Christian Enz, Yves Bellouard, Olivier Bernard, Assim Boukhayma, Andrea Kraxner

During the last two decades, ultrafast in-volume laser-based processing of transparent materials has emerged as a key 3D-printing method for manufacturing a variety of complex integrated photonic devices and micro-parts. Yet, identifying suitable laser pro ...

2023

Formation Mechanism of Elemental Te Produced in Tellurite Glass Systems by Femtosecond Laser Irradiation

Yves Bellouard, Gözden Torun

The formation of elemental trigonal tellurium (t-Te) on tellurite glass surfaces exposed to femtosecond laser pulses is discussed. Specifically, the underlying elemental crystallization phenomenon is investigated by altering laser parameters in common tell ...

Wiley2023

High-efficiency non-ablative UV laser nano-scale processing of fused silica by stable filamentation

Yves Bellouard, Olivier Bernard, Benedikt Hermann, Luca Muscarella

Over the last decades, three-dimensional micro-manufacturing of fused silica via near-infrared ultrafast laser exposure combined with an etching step has become an established technique for producing complex three-dimensional components. Here, we explore t ...

2023

All-glass miniature GHz repetition rate femtosecond laser cavity

Yves Bellouard, Antoine Maxime Delgoffe, Sargis Hakobyan, Saood Ibni Nazir

Free-space optics allows for design freedom and control, but miniaturization and manufacturability are limited. Here, we present a method for manufacturing complex miniaturized free-space optical systems that combines contactless femtosecond laser-activate ...

2023