Gwenn Ulliac

University of Franche-Comté | UFC · Institut FEMTO-ST

Materials and structures with tunable mechanical properties are essential for numerous applications. However, constructing such structures poses a great challenge since it is normally very complicated to change the properties of a material after its fabrication, particularly in pure force fields. Herein, we propose a multi-step and elastically stab...

Optical Microrobots (Optobots) have demonstrated a keen interest in various fields including microfluidics, microrobotics, and medicine. Conversely, optomechanics serves as a crucial domain for theoretical exploration into concepts such as chirality, duality, and parity concerning optical forces. In this paper, we elucidate a method to amalgamate c...

Non-Newtonian liquids are characterized by stress and velocity-dependent dynamical response. In elasticity, and in particular, in the field of phononics, reciprocity in the equations acts against obtaining a directional response for passive media. Active stimuli-responsive materials have been conceived to overcome it. Significantly, Milton and Will...

The ability to control Poisson's ratio of functional materials has been one of the main objectives of researchers attempting to develop structures efficient from the perspective of protective, biomedical and soundproofing devices. This task becomes even more challenging at small scales, such as the microscale, where the possibility to control mecha...

The ability to significantly change the mechanical and wave propagation properties of a structure without rebuilding it is currently one of the main challenges in the field of mechanical metamaterials. This stems from the enormous appeal that such tunable behavior may offer from the perspective of applications ranging from biomedical to protective...

Over the years, research and development into micro-force sensing techniques has gained a lot of traction, especially for microrobotic applications, such as micromanipulation and biomedical material characterization studies. Moreover, in recent years, new microfabrication techniques have been developed, such as two-photon polymerization (2PP), whic...

Energy absorption and dissipation features of mechanical metamaterials have widespread applications in everyday life, ranging from absorbing shock impacts to mechanical vibrations. This article proposes novel bioinspired friction‐based mechanical metamaterials with a zero Poisson's ratio behavior inspired from parrot's beaks and manufactured additi...

Non-Newtonian liquids are characterized by a stress and velocity-dependent dynamical response. In elasticity, and in particular in the field of phononics, reciprocity in the equations acts against obtaining a directional response for passive media. Active stimuli-responsive materials have been conceived to overcome it. Significantly, Milton and Wil...

The ability to change significantly mechanical and wave propagation properties of a structure without rebuilding it has been one of the main challenges in the field of mechanical metamaterials. This stems from the enormous appeal that, especially in the case of micro-scale systems, such tunable behavior may offer from the perspective of application...

In this paper, we propose a mobile microgripper actuated using laser optothermal and magnetic actuation in liquid environments. This hybrid actuation scheme allows the full decoupling between the in-plane positioning of the mobile microgripper and the actuation of its gripping mechanism, which reduces the control complexity of such microgrippers. T...

In solid state physics, phase transitions can influence material functionality and alter their properties. In mechanical metamaterials, structural-phase transitions can be achieved through instability or buckling of certain structural elements. However, these fast transitions in one mechanical parameter typically affect significantly the remaining...

Well-designed stretching-dominated lattices can form elastic metamaterials with high specific stiffness and strength. Their strongly anisotropic and unstable nonlinear mechanical properties, however, limit their application to energy absorption. In contrast, bending-dominated lattices are well known for high energy absorption capacity and stable no...

Stepper motors and actuators are among the main constituents of control motion devices. They are complex multibody systems with rather large overall volume due to their multifunctional parts and elaborate technological assembly processes. Miniaturization of individual parts is still posing assembly problems. In this paper, a single‐step lithography...

Three-dimensional direct laser writing technology enables one to print polymer microstructures whose size varies from a few hundred nanometers to a few millimeters. It has been shown that, by tuning the laser power during writing, one can adjust continuously the optical and elastic properties with the same base material. This process is referred to...

Periodic truss-lattice materials, especially when combined with current additive manufacturing techniques, are attracting attention in lightweight material engineering. As a member of the elementary cubic truss family, the simple-cubic truss lattice possesses the highest stiffness and strength along the principal directions and plays an important r...

Shape morphing and the possibility of having control over mechanical properties via designed deformations have attracted a lot of attention in the materials community and led to a variety of applications with an emphasis on the space industry. However, current materials normally do not allow to have a full control over the deformation pattern and o...

In this article, we propose laser actuated microjoints which can be remotely actuated in both air and water. Their actuation relies on the optothermal response of a spiral bimaterial. The microjoints are fabricated using two-photon polymerization technology that offers the ability to tune the thermal and mechanical properties of the material by con...

Metamaterials have attracted wide scientific interest to break fundamental bounds on materials properties. Recently, the field has been extending to coupled physical phenomena where one physics acts as the driving force for another. Stimuli-responsive or 4D metamaterials have been demonstrated for thermo-elasticity, magneto-optics or piezo-electric...

Several integrated optics solutions currently exist to develop monolithic, robust, and lightweight high-resolution spectrometers for spatial applications. An interesting option is generating a stationary wave inside a single-mode waveguide, and sampling the interference fringes using dielectric discontinuities on the surface of the waveguide. This...

Phononic crystals have attracted wide attention in diverse scientific communities due to their ability to efficiently reflect, focus, and guide acoustic and elastic waves. Their use in ultrasonic applications such as medical imaging, however, remains elusive since three-dimensional phononic crystals with lattice constants in the range of hundreds o...

Metamaterials are rationally designed composites made of building blocks which are composed of one or more constituent materials. Metamaterial properties can go beyond those of the ingredient materials, both qualitatively and quantitatively. In addition, their properties can be mapped on some generalized continuum model. We present the general proc...

Photonic waveguides are prime candidates for integrated and parallel photonic interconnects. Such interconnects correspond to large-scale vector matrix products, which are at the heart of neural network computation. However, parallel interconnect circuits realized in two dimensions, for example, by lithography, are strongly limited in size due to d...

Cork is a natural amorphous material with near-zero Poisson's ratio that is ubiquitously used for sealing glass bottles. It is an anisotropic, transversally isotropic, composite that can hardly be scaled down. Here, we propose a new class of isotropic and reusable cork-like metamaterial that is designed from an hybrid truss-lattice material to show...

Photonic waveguides are prime candidates for integrated and parallel photonic interconnects. Such interconnects correspond to large-scale vector matrix products, which are at the heart of neural network computation. However, parallel interconnect circuits realized in two dimensions, for example by lithography, are strongly limited in size due to di...

Lithium niobate (LN)-based devices are widely used in integrated and nonlinear optics. This material is robust and resistive to high temperatures, which makes the LN-based devices stable, but challenging to fabricate. In this work, we report on the design, manufacturing, and characterization of engineered dielectric media with thin-film LN (TFLN) o...

The stationary wave integrated Fourier transform spectrometer (SWIFTS) is based on the sampling of a stationary wave using nano-scattering centers on the surface of a channel waveguide. Single nano-scale scattering centers above the waveguide surface will radiate the sampled signal with wide angular distribution, which is not compatible with the bu...

Stationary Wave Integrated Fourier Transform Spectrometers (SWIFTS) are based on the sampling of a stationary wave using nano-scattering centers on the surface of a channel waveguide. Single nano-scale scattering centers above the waveguide surface will radiate the sampled signal with wide angular distribution, which is not compatible with the buri...

In a Fourier Transform spectrometer, the main issue is to sample an interferogram with a small spatial step and over a large number of fringe periods resulting in a long sampling distance. The first condition is linked to the spectral etendue or the wavelength range to analyze, whereas the second one is linked to the spectral resolution achievable....

Lithium niobate (LN) based devices are widely used in integrated and nonlinear optics. This material is robust and resistive to high temperatures, which makes the LN-based devices table, but challenging to fabricate. In this work we report on the design, manufacturing and characterization of engineered dielectric media with thin film lithium niobat...

As high aspect ratio ridges are not easy to process with standard lithographic techniques, we propose alternative solutions based on atomic layer deposition and precise dicing to allow both uniform coating of the relief surface and a selective lift-off at the top of the ridges. The techniques are successfully employed to demonstrate an electro-opti...

Mid-infrared wideband modulation (3.2–3.7 μm) is achieved in an electro-optic Y-junction using lithium niobate waveguides in TE polarized light. Comparison between external (scanning mirror) and internal (electro-optical) modulation allows studying the chromatic polynomial dependence of the relative phase. Internal modulation consists on a V AC ram...

We report on free-standing electro-optical LiNbO 3 waveguides with integrated tapers made by optical grade dicing. Membranes with a calibrated thickness are produced simultaneously with tapers acting as spot-size converters. Thereby, thicknesses from 450 to 500 μm can simply be achieved together with integrated tapers guaranteeing low insertion los...

We present visible range achromatic beam combiners using electro-optic waveguides devoted to cubesat interferometry projects, and developments in hybrid active-passive integrated optics interferometers for a nine channel beam combiner FIRST instrument at Subaru telescope

Compact photonic structures have strategic importance in several fields. In order to fabricate more complex structures with optimized optical function, robotic nano-assembly is a promising solution because it enables to integrate several types of materials from different fabrication processes into the same structure. This paper presents a microrobo...

Integrated optics spectrometers can be essentially classified into two main families: based on Fourier transform or dispersed modes. In the first case, an interferogram generated inside an optical waveguide is sampled using nanodetectors, these scatter light into the detector that is in contact with the waveguide. A dedicated FFT processing is need...

We report light-beam self-trapping triggered by the pyroelectric effect in an isolated ferroelectric thin film. Experiments are performed in an 8-μm-thick congruent undoped LiNbO 3 film bonded onto a silicon wafer. Response time two orders of magnitude faster than in bulk LiNbO 3 is reported. The original underlying physics specific of this arrange...

We report on the direct observation of trapping and guiding of surface-guided elastic waves in a linear defect introduced into a micron-scale phononic crystal. Elastic field amplitude detection using laser scanning interferometry was used to characterize the different transmission regimes of the one-period wide line defect in a phononic crystal str...

High-resolution spectrometers are nowadays achievable in compact devices using integrated optics. The approach developed here consists in obtaining a static interferogram by means of a Fresnel reflection at the waveguide output (Lippmann interference between forward and backward beams) and then sample the fringes by periodically etching the wavegui...

The context of this work is the development of integrated optic beam combiners devoted to high contrast interferometry, in particular for exoplanet spectral characterization and future spatial missions, where the use of compact and light optical beam combiners ensures robustness and stability of the interferometric signal. Thus, the development of...

We optically characterize a micrometric radio frequency electro-optic modulator based on a lithium niobate photonic crystal. With the vertically deposited sidewalls electrodes, the experimental results show a half-wave voltage length product (V_{pi }{}^* L) figure of merit of 0.0063 V-cm, a bandwidth of (sim 1) GHz for an active interaction area of...

We present easy-to-implement technologies to produce LiNbO3 PhCs in confined optical waveguides. Ti-indiffusion or Annealed Proton Exchange (APE) are combined with optical grade dicing to fabricate ridge waveguides with propagation losses that can be lower than 0.2 dB/cm. Firstly we show how a PhC inscribed in a confined ridge waveguide can be expl...

In this Letter, we report a technique to etch giant aspect ratio nanostructures in lithium niobate. An 8 μm long Bragg grating on a Ti : LiNbO 3 ridge waveguide was fabricated by combining optical-grade dicing and focused ion beam milling. The reflectivity was evaluated using an optical coherence tomography system: it is measured to be 53% for the...

The development of all-optical, acousto-optical or electro-optical photonic crystals (PhCs) represents a stimulating challenge for the production of advanced functionalities in compact optical devices. LiNbO3 appears as an excellent candidate for such realizations, due to its well-known nonlinear, piezoelectric and electro-optic properties. Two mai...

We benefit from the recent progress on lithium niobate deep etching to enhance the extinction ratios of Mach-Zehnder modulators. We demonstrate that a proper trench placed in between parallel arms can lead to a 15 dB- increase without any additional losses at 1550 nm.

The constant improvement of industrial needs to face modern telecommunication challenges leads to the development of novel transducer principles as alternatives to SAW and BAW solutions. The main technological limits of SAW (short-circuit between electrodes) and BAW (precise thickness control) solutions can be overcome by a new kind of transducer b...

A five micrometer long Bragg grating in titanium indiffused lithium niobate ridge waveguide was fabricated by combining optical grade dicing and Focused Ion Beam. The 53% reflectivity is measured using a swept-source optical coherence tomography.

In this paper, temperature variations are detected thanks to an enhanced nano-optical pyroelectric sensor. Sensing is obtained with the pyroelectric effect of lithium niobate (LN) in which, a suitable air-membrane photonic crystal cavity has been fabricated. The wavelength position of the cavity mode is tuned 11.5 nm for a temperature variation of...

We here report on the fabrication of electroplated nickel (Ni) masks for dry etching of sub-micron patterns in lithium niobate (LiNbO3). This process allows obtaining 350-nm thick Ni masks defining high air filling fraction holey arrays (e.g. openings of 1800 nm in diameter with inter-hole spacing of 300 nm, or 330 nm diameter holes spaced by 440 n...

Fabrication processes implemented for the realization of micron-sized patterns in lithium niobate are presented, in view of applications to nanophotonics and phononics. Collective processes based on reactive ion etching in fluorine chemistries as well as FIB milling are discussed.

We report an electro-optically tunable filter using a lithium niobate photonic crystal cavity configuration with an efficient optical guiding geometry. The compact device (5.5 μm × 2.8 μm) was made on a hybrid waveguide combining an annealed proton exchange waveguide and a ridge waveguide realized by focused ion beam with vertically deposited elect...

Passive radiofrequency filters and resonators exploited for telecommunication applications are generally based on surface or bulk acoustic wave (SAW or BAW) devices. However, these devices present some technological limits as short-circuits between the electrodes of the interdigital transducers (for SAW devices) or an accurate control of the resona...