LiNbO3 acousto-optical and electro-optical micromodulators

We report on acousto-optical (AO) and electro-optical (EO) LiNbO3 modulators with an active length of only 11 µm. The miniature devices are based on photonic crystal (PhC) structures that are controlled by an external effect (DC electric field or Surface Acoustic Waves). Two processes are presented for realizing the PhCs despite the resistance of the material to etching. The first method is based on direct FIB writing and can yield the fabrication of holes with depth of 32 m and diameter of 12 m or less. The second method consists in FIB patterning of a mask which is deposited on the substrate. This process is followed by proton exchange (PE) and reactive ion etching (RIE). Thus, structures with a diameter of 400 nm and an aspect ratio of 3:1 have been fabricated. The methods have been applied to the fabrication of EO and AO micromodulators showing a driving voltage of 13,5 V and a driving electric power of 20 mW respectively. These developments open the way to dense integration of dynamic optical functionalities

Parrot beak‐inspired metamaterials with friction and interlocking mechanisms 3D/4D printed in micro and macro scales for supreme energy absorption/dissipation

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 additively. The mechanical performances of the corresponding metamaterials are studied at both macro and micro scales by experiments and finite element analysis (FEA). An excellent agreement is observed between the FEA and both microscopic and macroscopic scale experiments, showing the accuracy of the developed digital tool. Performances are compared to traditional triangular lattice metamaterials. Both experimental tests and FEA results demonstrate the following advantages: 1) absorbing and dissipating energy per unit of mass (SEA) at large compressive strains without global buckling; 2) bistable deformation patterns including friction-based and interlocking mechanisms; 3) reversible deformation patterns after unloading; 4) shape recovery behavior after a heating–cooling process; and 5) the higher elastic modulus of micro metamaterials compared with their macro counterparts. This is the first demonstration of a bioinspired friction-based design of 3D-printed mechanical metamaterials that feature absorbing/dissipating energy, stability, and reversibility properties to cater to a wide range of sustainable meta-cylinders in micro and macro scales

Fabrication collective de cristaux photoniques LiNbO3

International audienc

Batch process for the fabrication of LiNbO3 photonic crystals using proton exchange followed by CHF3 reactive ion etching

International audienceWe report a simple process for the batch fabrication of photonic crystals in lithium niobate substrates. By means of proton-exchange (PE) followed by CHF3 reactive ion etching (RIE) we have achieved structures with a diameter of 400 nm and an aspect ratio (depth-to-diameter) of 3:1. Sub-micrometric structures have been fabricated with an 85 degrees angle between the walls and the plane of the substrate. We provide the optimized parameters - and their influence on the aspect ratio, the etching rate and the verticality of the walls. Transversal cross-section micrographs of the etched patterns, for both X-cut and Z-cut substrates, are shown as a clear evidence of the capability developed. (C) 2008 Elsevier B.V. All rights reserved

Etude et réalisation d'une structure à cristaux photoniques en niobate de lithium pour la modulation électro-optique

National audienc

Acoustic Wave Filter Based on Periodically Poled Lithium Niobate

International audienceWe present results on the development of an acoustic bandpass filter based on periodically poled ferroelectric domains in lithium niobate. The fabrication of Periodically Poled Transducers (PPT) operating in the range 20 - 650 MHz has been achieved on a 3 '' 500 mu m thick wafer. This kind of transducer enables to excite elliptical as well as longitudinal modes, yielding phase velocity of about 3800 and 6500 m. s(-1) respectively. We propose then a new type of acoustic bandpass filter based on the use of PPTs instead of classical IDTs. The design and the fabrication of such a filter are presented as well as the experimental measurements. Finally we demonstrate the feasibility of such a PPTs-based filter

Étude et réalisation des cavités photoniques sur niobate de lithium

Nous présentons des cavités photoniques, fabriquées par faisceau d'ions focalisés (FIB), sur des guides d'ondes réalisés sur un substrat de niobate de lithium. Des résultats théoriques et expérimentaux, en champ proche et lointain, seront présentés. Nous montrons aussi une solution pour pouvoir exalter le mode de résonance de la cavité en champ lointain