Gwenn Ulliac

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

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113
Publications
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974
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Publications

Publications (113)
Article
Full-text available
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Preprint
Full-text available
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...
Preprint
Full-text available
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...
Article
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...
Article
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...
Preprint
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...
Article
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....
Preprint
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...
Article
Full-text available
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...
Article
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 VAC ramp...
Article
Full-text available
We report on free-standing electro-optical LiNbO3 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 loss...
Conference Paper
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
Article
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...
Article
Full-text available
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 LiNbO3 film bonded onto a silicon wafer. Response time two orders of magnitude faster than in bulk LiNbO3 is reported. The original underlying physics specific of this arrangeme...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Conference Paper
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
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<sub>3</sub> 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%...
Chapter
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...
Article
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.
Article
Full-text available
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...
Article
Full-text available
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...
Conference Paper
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.
Article
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...
Conference Paper
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.
Article
Full-text available
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...
Article
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...
Article
In this paper, waveguide mode sizes are determined by using the variational method. This approach has been used with both optical fibers and integrated optics. In the case of the integrated waveguide a comparison of theoretical and experimental results has been carried out with only limited success, although the geometric mean of the calculated ort...
Article
Full-text available
We report on electro-optic modulation using a Lithium Niobate (LN) Photonic Crystal (PC) cavity structure. The compact device (6 μm in length) consists of a 2D photonic crystal cavity made on an Annealed Proton Exchange (APE) LN waveguide with vertical deposited electrodes. Experimental results show a tunability of 0.6 nm/V. This compact design ope...
Article
Solutions for the development of compact RF passive transducers as an alternative to standard surface or bulk acoustic wave devices are receiving increasing interest. This article presents results on the development of an acoustic band-pass filter based on periodically poled ferroelectric domains in lithium niobate. The fabrication of periodically...
Article
We report on three approaches to achieve 1086 nm period Bragg Gratings structures (BGs), corresponding to the third Bragg order at 1550 nm, on X-cut lithium niobate (LiNbO3) substrates. The first method relies on Reactive Ionic Etching (RIE) with fluorine gases, associated with e-beam lithography and electroplating deposition. BGS with etched angle...
Article
We present our work on integrated optic beam combiners devoted to mid-infrared applications in the field of stellar interferometry, in particular for nulling interferometry, where high rejection ratios are needed. The main results obtained are the single-mode behavior of the waveguides at a central wavelength λ=3.39μm, in both TE and TM polarizatio...
Conference Paper
Full-text available
Abstract—The development of transducers alternative to usual surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices for RF signal processing is strongly motivated by the need for improved operating characteristics to face modern telecommunication challenges. This paper shows the interest of a new concept of periodically poled transducers...
Article
The demand for highly coupled high quality acoustic wave devices for radio-frequency (RF) signal processing based on passive devices has generated a strong innovative activity, yielding the investigation of new excitation principles and waveguide structures. Periodically poled transducers (PPTs) have been recently investigated [E. Courjon et al., J...
Article
Full-text available
We report an electro-optically tunable photonic crystal linear cavity etched on a 200 nm lithium niobate waveguide ridge. The photonic crystal cavity and the ridge are both fabricated on a 1 μm thin film of lithium niobate obtained by smart-cut technology. The photonic crystal, of area 4x0.8 μm2, has been engineered to work in a slow light configur...
Article
This paper described a wavelength-selective couplers dedicated to drop functionality (spectral-selective couplers dedicated to wavelength demultiplexing). It is consist of two Y junctions: an input two drop channels and an output. The Y-branches distributors of optical power were carried out by a specific geometry of Ti:LiNbO<sub>3</sub> waveguides...
Article
Full-text available
We report easy-to-implement techniques to improve the reflectivity of LiNbO₃ photonic crystals within the photonic bandgap. Firstly, we show that widening the channel waveguides confines the optical modes in the vertical direction, which leads to the development of the first 2D-PhCs on Ti-indiffused LiNbO₃ waveguides. We also report the first optic...
Article
We report the characterization of a lithium niobate photonic crystal cavity using near field scanning optical microscopy (NSOM) operating in collection scanning mode. The cavity is implemented on an annealed proton exchange waveguide by focused ion beam milling. We observe a confinement of the optical field at the center of the cavity by analyzing...