Publications by Yves Bellouard

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Chalcogenide glass exhibits a wide transmission window in the infrared range, a high refractive index, and nonlinear optical properties; however, due to its poor mechanical properties and low chemical and environmental stability, producing three-dimensiona ...

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 ...

The general trend for miniaturization leads to widespread use of micro-optical elements for various applications including optical communications, embedded photonic systems, beam shaping and imaging. We propose here a cost-effective manufacturing method for complex 3D micro-optics based on femtosecond laser-manufactured of simple glass preforms that are topologically transformed into complex 3D objects with optical surface quality through a localized laser-induced viscous flow of the surface. Using this pri

The concept of monolithic shape memory alloys (SMA) micro-devices is to integrate all device functions within the same piece of material. This is very interesting in the field of micro-systems, because assembly is avoided. In such devices, the main problem is to create a reversible motion. Recently, the use of the two-way shape memory effect has been investigated. A simpler solution could be to integrate a pullback spring within the monolithic structure. This implies introducing shape memory properties only

Femtosecond laser pulses used in a regime below the ablation threshold have two noticeable effects on Fused Silica (a-SiO2): they locally increase the material refractive index and modify its HF etching selectivity. The nature of the structural changes ind ...

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 ...

Femtosecond laser irradiation has various noticeable effects on fused silica. It can locally increase the index of refraction and modify the material chemical selectivity. Regions that have been exposed to the laser are etched hundred fold faster than unexposed regions. These effects are of practical importance from an application point-of-view and open new opportunities for the development of integrated photonics devices that combine structural and optical functions. Various observations reported in the li

Multi-scale 3D architecture with highly localized fluorescence contrast in photosensitive silver-containing glasses by means of femtosecond laser writing can be obtained. We will present results obtained on electron-irradiated glass samples by EPR spectroscopy and in-situ cathodoluminescence. This allowed for understanding the initial phenomena of electron deposition and charge trapping by identifying the nature of point defects and Ag species. In addition, a careful point defects analysis of fs-laser writt

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 ...

During the embryonic development of vertebrates, initially, symmetric embryos develop asymmetrically arranged organs. The asymmetry initiates with the formation of a small fluid-filled cavity on the embryo called the embryonic node, which contains motile cilia that generate specific flow patterns. The mechanism by which this nodal flow is sensed and causes asymmetry development has remained elusive despite major experimental and computational efforts. Existing hypotheses focus on either mechanical or chemic

Morphing refers to the smooth transition from a specific shape into another one, in which the initial and final shapes can be significantly different. A typical illustration is to turn a cube into a sphere by continuous change of shape curvatures. Here, we ...

High-finesse optical microcavities are at the core of a wide range of scientific advances and technical applications from quantum technologies to optical sensors. Among them, fiber Fabry-Perot cavities (FFPCs) are of particular interest because of their unique properties. However, integrating FFPCs into photonic devices remains difficult because it is complex to individually tune their resonance frequencies. Moreover, integrating them in a miniaturized device is an experimental challenge prone to errors. To

High-finesse optical microcavities are at the core of a wide range of scientific advances and technical applications from quantum technologies to optical sensors. Among them, fiber Fabry-Perot cavities (FFPCs) are of particular interest because of their unique properties. However, integrating FFPCs into photonic devices remains an experimental challenge prone to errors. To tackle this limitation, we combined FFPCs with femtosecond laser manufacturing to assemble an all-glass FFPC integrated on a microstruct

Femtosecond laser offers a means to confine energy beyond the diffraction limit. Applied to glass, this high energy confinement leads to intriguing modification of the glass structure, inducing a variety of events such as nano-crystallization, amorphization or phase separation. Here, we review these structural modifications, their observations as well as means to control it and one can achieve nanoscale confinement along the laser propagation axis. Furthermore, we discuss how they can be used in the context

An innovative surgical tool prototype dedicated to safe puncturing has been developed for the treatment of retinal vein occlusions (RVOs). The tool is manufactured monolithically by femtolaser printing in fused silica. It consists of a programmable bistabl ...

The Two-Way Shape Memory Effect (TWSME) has been widely studied in the literature. However, little attention has been paid about the out-of-equilibrium behavior of the TWSME. This paper reports some experiments, which were performed on specimens, previously trained in bending according a constrained temperature cycling process. Once the training process was done, specimens were deformed in their martensitic state such as a permanent deformation remains. In other words, specimens were set in a position that

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 ...

Third harmonic generation (THG) microscopy offers label-free imaging and enables three-dimensional imaging with inherently good optical depth-sectioning. Its utility is important for imaging and characterization of laser-induced changes in transparent materials. Here we develop a digital twin for THG microscopy that allows accurate simulation of experiments and provides insight into desired information such as the third-order nonlinear susceptibility tensor. It also enables accurate simulation of the instru

Flexures are used in precision engineering where highly accurate, wear-free, smooth and repeatable motion is desired. Flexures are based on deformation of material to achieve a motion between elastically joined parts. They are used in a variety of precision mechanisms such as high-resolution balances or high accuracy optical positioning stages. Shape memory alloys (SMA) are an attractive option in designing flexures. Superelastic flexures can withstand larger deformations for the same weight as a convention

Raman spectroscopy is the workhorse for label-free analysis of molecules. It relies on the inelastic scattering of incoming monochromatic light impinging molecules of interest. This effect leads to a very weak emission of light spectrum that provides a sig ...

Yves Bellouard

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Glass-in-glass infiltration for 3D micro-optical composite components

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

Manufacturing of 3D glass micro-optics through laser assisted topological transformation

Local annealing of complex mechanical devices: a new approach for developing monolithic micro-devices

Nanoindentation and birefringence measurements on fused silica specimen exposed to low-energy femtosecond pulses

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

Investigation of Femtosecond Laser Irradiation on Fused Silica

Glass for photonics: insight in the glass properties obtained under laser fs writing via point defects analysis

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

Artificial embryonic node elucidates the role of flow in left-right symmetry breaking in vertebrates

Laser-assisted morphing of complex three dimensional objects

An all glass, high finesse miniature integrated fiber Fabry-Perot microcavity produced by 3D femtosecond laser processing

Femtosecond laser processing of an integrated fiber Fabry-Perot cavity device in glass

Functional integration through femtosecond laser-induced nano-structuration of glass

Bistable Puncturing Tool for Retinal Vein Cannulation

Experimental study of the out-of-equilibrium behavior of the two-way shape memory effect

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

Leveraging computational imaging for enhanced third-harmonic generation microscopy

Shape memory alloy flexures

Plasmon-less surface enhanced Raman spectra induced by self-organized networks of silica nanoparticles produced by femtosecond lasers