18 research outputs found
Temperature coefficients of crystalline-quartz elastic constants over the cryogenic range [4 K, 15 K]
This paper brings out results of a measurement campaign aiming to determine
the temperature coefficients of synthetic quartz elastic constants at liquid
helium temperature. The method is based on the relationship between the
resonance frequencies of a quartz acoustic cavity and the elastic constants of
the material. The temperature coefficients of the elastic constants are
extracted from experimental frequency-temperature data collected from a set of
resonators of various cut angles, because of the anisotropy of quartz, measured
on the very useful cryogenic range [4 K - 15 K]. The knowledge of these
temperature coefficients would allow to further design either quartz
temperature sensors or conversely frequency-temperature compensated quartz
cuts. With extremely low losses, lower than for the best ones, key
applications of such devices are ultra-low loss mechanical systems used in many
research areas including frequency control and fundamental measurements. The
Eulerian formalism is used in this study to identify the temperature
coefficients.Comment: 6 pages,4 figure
Operation of graphene-on-quartz acoustic cavity at cryogenic temperatures
This paper presents observation of mechanical effects of a graphene monolayer
deposited on a quartz substrate designed to operate as an extremely low-loss
acoustic cavity standard at liquid-helium temperature. Resonances of this
state-of-the-art cavity are used to probe the mechanical loss of the graphene
film, assessed to be about at 4K. Significant frequency shifts
of positive and negative sign have been observed for many overtones of three
modes of vibration. These shifts cannot be predicted by the mass-loading model
widely used in the Quartz Microbalance community. Although thermo-mechanical
stresses are expected in such a graphene-on-quartz composite device at low
temperature due to a mismatch of expansion coefficients of both materials, it
cannot fully recover the mismatch of the mass loading effect. Based on a
force-frequency theory applied to the three thickness modes, to reconcile the
experimental results, the mean stresses in the graphene monolayer should be of
the order of 140 GPa, likely close to its tensile strength.Comment: Corrected typos. New Fig. Text improve
A new method of probing mechanical losses of coatings at cryogenic temperatures
A new method of probing mechanical losses and comparing the corresponding
deposition processes of metallic and dielectric coatings in 1-100 MHz frequency
range and cryogenic temperatures is presented. The method is based on the use
of extremely high-quality quartz acoustic cavities whose internal losses are
orders of magnitude lower than any available coatings nowadays. The approach is
demonstrated for Chromium, Chromium/Gold and a multilayer tantala/silica
coatings. The coating has been found to
exhibit a loss angle lower than near 30 {\rm MHz} at 4 {\rm
K}. The results are compared to the previous measurements
Evolutionary genetic dissection of human interferons
As revealed by population genetic analyses, different human interferon genes evolved under distinct selective constraints and signatures of positive selection vary according to geographic region, suggesting that some sequence changes may have conferred an advantage by increasing resistance to viral infection
Résonateurs à ondes acoustiques de volume piégées à trÚs basses température : Applications à l'optomécanique
For a few years, the Time and Frequency department in FEMTO-ST Insitute has been leading research about the behavior of Bulk Acoustic Wave (BAW) trapped in quartz crystal at cryogenic temperatures (near 4K).The measured quality factor are around a few billions at few tens of MHz for such temperatures. Acoustical quartz cavities are therefore good candidates for ultrastable cryogenic frequency sources. The work presented here is in the natural continuation of the research cited above. They aim at strenghtening the interest for quartz crystal, but also to consider alternative solutions with non-piezoelectric material with very-low acoustical losses, for which optical excitation is an option. The following work can be summed up in three main parts:- The first part is about the determination of a quartz crystal cut for which a turnover point exists in the frequency-temperature curve in the cryogenic region. Indeed, it is not enough to barely control the temperature in an ultrastable frequency source. Such a turnover point needs to be the operation point for thermal regulation. Searching a compensated cut arose the need for a preliminary measurements campaign of thermal coefficients of elastics coefficients of the material, which were unknown at low temperature. It was then possible, based on these coefficients, to calculate and even realize a cut fulfilling the required condition.- The second part had the objective to demonstrate conceptually that using a quartz acoustical cavity as an optical cavity was feasible. In its basic scheme, a BAW quartz resonator is plano-convex (to ensure the trapping of the acoustic wave) and has electrodes (metal-made to ensure electrical excitation) deposited on each face. It has been demonstrated, both theoretically and experimentally, that such a geometry works fine as an optical cavity, with its corresponding advantages and limitations. This scheme is used for the optomechanical coupling discussed in the third part and constitutes the very base for more efficient optomechanical devices.- The third part is dedicated to the evaluation of how efficient will such devices be while functioning at cryogenic temperature. A theoretical quantification of the optomechanical coupling that these cavities might reach is also presented.Depuis plusieurs annĂ©es, le dĂ©partement Temps-FrĂ©quence de lâinstitut FEMTO-ST mĂšne une Ă©tude sur le comportement des rĂ©sonateurs Ă ondes acoustiques de volume Ă Ă©nergie piĂ©gĂ©e dans des cristaux Ă quartz Ă tempĂ©rature cryogĂ©nique, typiquement proche de 4 K. Les performances en termes de coefficient de qualitĂ© mĂ©canique relevĂ© Ă ces tempĂ©ratures, plusieurs milliards Ă quelques dizaines de MHz, font des cavitĂ©s acoustiques en quartz de bons candidats pour des sources de frĂ©quences cryogĂ©niques ultrastables.Les travaux prĂ©sentĂ©s dans ce manuscrit sâinscrivent dans la continuitĂ© de ce programme dâĂ©tude. Ils visent Ă consolider lâintĂ©rĂȘt du quartz mais aussi Ă envisager des solutions alternatives Ă base de matĂ©riaux Ă trĂšs faibles pertes acoustiques mais non piĂ©zoĂ©lectriques pour lesquels lâexcitation optique est une alternative crĂ©dible. Les prĂ©sents travaux peuvent ĂȘtre rĂ©sumĂ©s en trois parties majeures :- La premiĂšre partie a Ă©tĂ© rĂ©alisĂ©e dans le but de dĂ©terminer une coupe de quartz possĂ©dant un point dâinversion sur sa caractĂ©ristique frĂ©quence-tempĂ©rature aux tempĂ©ratures cryogĂ©niques. La seule rĂ©gulation de tempĂ©rature du rĂ©sonateur dâune source de frĂ©quence ultrastable est en effet insuffisante sans lâexistence dâun tel point qui doit servir de point de fonctionnement Ă la rĂ©gulation thermique. La recherche dâune coupe compensĂ©e a nĂ©cessitĂ© une campagne prĂ©liminaire de mesure des coefficients de tempĂ©rature des coefficients Ă©lastiques du matĂ©riau, inconnus Ă basses tempĂ©ratures. Il a alors Ă©tĂ© possible, Ă partir de la connaissance de ces coefficients, dâidentifier par le calcul puis de rĂ©aliser une coupe remplissant les conditions recherchĂ©es.- La seconde partie a pour objectif de faire la preuve de concept consistant Ă utiliser une cavitĂ© acoustique en quartz en cavitĂ© optique. Dans sa version de base, le rĂ©sonateur Ă quartz Ă onde de volume piĂ©gĂ©e est plan-convexe (pour assurer le piĂ©geage) et Ă Ă©lectrodes (mĂ©talliques pour assurer lâexcitation Ă©lectrique !) dĂ©posĂ©es sur chacune de ses faces. Il est dĂ©montrĂ©, thĂ©oriquement et expĂ©rimentalement, quâune telle gĂ©omĂ©trie fonctionne en cavitĂ© optique, avec son avantage de simplicitĂ© mais avec ses limites. Cette structure de base doit ĂȘtre mise Ă profit pour le couplage optomĂ©canique abordĂ© en troisiĂšme partie et constitue le socle de conception de dispositifs optomĂ©caniques plus performants.- La troisiĂšme partie est consacrĂ©e Ă lâĂ©valuation de la pertinence du couplage optomĂ©canique de tels dispositifs fonctionnant Ă tempĂ©rature cryogĂ©nique. Une Ă©tude portant sur la quantification thĂ©orique du couplage optomĂ©canique que peut atteindre une telle cavitĂ© a Ă©tĂ© rĂ©alisĂ©e
Bulk acoustics waves resonators trapped at very low temperatures : Optomechanical applications
Depuis plusieurs annĂ©es, le dĂ©partement Temps-FrĂ©quence de lâinstitut FEMTO-ST mĂšne une Ă©tude sur le comportement des rĂ©sonateurs Ă ondes acoustiques de volume Ă Ă©nergie piĂ©gĂ©e dans des cristaux Ă quartz Ă tempĂ©rature cryogĂ©nique, typiquement proche de 4 K. Les performances en termes de coefficient de qualitĂ© mĂ©canique relevĂ© Ă ces tempĂ©ratures, plusieurs milliards Ă quelques dizaines de MHz, font des cavitĂ©s acoustiques en quartz de bons candidats pour des sources de frĂ©quences cryogĂ©niques ultrastables.Les travaux prĂ©sentĂ©s dans ce manuscrit sâinscrivent dans la continuitĂ© de ce programme dâĂ©tude. Ils visent Ă consolider lâintĂ©rĂȘt du quartz mais aussi Ă envisager des solutions alternatives Ă base de matĂ©riaux Ă trĂšs faibles pertes acoustiques mais non piĂ©zoĂ©lectriques pour lesquels lâexcitation optique est une alternative crĂ©dible. Les prĂ©sents travaux peuvent ĂȘtre rĂ©sumĂ©s en trois parties majeures :- La premiĂšre partie a Ă©tĂ© rĂ©alisĂ©e dans le but de dĂ©terminer une coupe de quartz possĂ©dant un point dâinversion sur sa caractĂ©ristique frĂ©quence-tempĂ©rature aux tempĂ©ratures cryogĂ©niques. La seule rĂ©gulation de tempĂ©rature du rĂ©sonateur dâune source de frĂ©quence ultrastable est en effet insuffisante sans lâexistence dâun tel point qui doit servir de point de fonctionnement Ă la rĂ©gulation thermique. La recherche dâune coupe compensĂ©e a nĂ©cessitĂ© une campagne prĂ©liminaire de mesure des coefficients de tempĂ©rature des coefficients Ă©lastiques du matĂ©riau, inconnus Ă basses tempĂ©ratures. Il a alors Ă©tĂ© possible, Ă partir de la connaissance de ces coefficients, dâidentifier par le calcul puis de rĂ©aliser une coupe remplissant les conditions recherchĂ©es.- La seconde partie a pour objectif de faire la preuve de concept consistant Ă utiliser une cavitĂ© acoustique en quartz en cavitĂ© optique. Dans sa version de base, le rĂ©sonateur Ă quartz Ă onde de volume piĂ©gĂ©e est plan-convexe (pour assurer le piĂ©geage) et Ă Ă©lectrodes (mĂ©talliques pour assurer lâexcitation Ă©lectrique !) dĂ©posĂ©es sur chacune de ses faces. Il est dĂ©montrĂ©, thĂ©oriquement et expĂ©rimentalement, quâune telle gĂ©omĂ©trie fonctionne en cavitĂ© optique, avec son avantage de simplicitĂ© mais avec ses limites. Cette structure de base doit ĂȘtre mise Ă profit pour le couplage optomĂ©canique abordĂ© en troisiĂšme partie et constitue le socle de conception de dispositifs optomĂ©caniques plus performants.- La troisiĂšme partie est consacrĂ©e Ă lâĂ©valuation de la pertinence du couplage optomĂ©canique de tels dispositifs fonctionnant Ă tempĂ©rature cryogĂ©nique. Une Ă©tude portant sur la quantification thĂ©orique du couplage optomĂ©canique que peut atteindre une telle cavitĂ© a Ă©tĂ© rĂ©alisĂ©e.For a few years, the Time and Frequency department in FEMTO-ST Insitute has been leading research about the behavior of Bulk Acoustic Wave (BAW) trapped in quartz crystal at cryogenic temperatures (near 4K).The measured quality factor are around a few billions at few tens of MHz for such temperatures. Acoustical quartz cavities are therefore good candidates for ultrastable cryogenic frequency sources. The work presented here is in the natural continuation of the research cited above. They aim at strenghtening the interest for quartz crystal, but also to consider alternative solutions with non-piezoelectric material with very-low acoustical losses, for which optical excitation is an option. The following work can be summed up in three main parts:- The first part is about the determination of a quartz crystal cut for which a turnover point exists in the frequency-temperature curve in the cryogenic region. Indeed, it is not enough to barely control the temperature in an ultrastable frequency source. Such a turnover point needs to be the operation point for thermal regulation. Searching a compensated cut arose the need for a preliminary measurements campaign of thermal coefficients of elastics coefficients of the material, which were unknown at low temperature. It was then possible, based on these coefficients, to calculate and even realize a cut fulfilling the required condition.- The second part had the objective to demonstrate conceptually that using a quartz acoustical cavity as an optical cavity was feasible. In its basic scheme, a BAW quartz resonator is plano-convex (to ensure the trapping of the acoustic wave) and has electrodes (metal-made to ensure electrical excitation) deposited on each face. It has been demonstrated, both theoretically and experimentally, that such a geometry works fine as an optical cavity, with its corresponding advantages and limitations. This scheme is used for the optomechanical coupling discussed in the third part and constitutes the very base for more efficient optomechanical devices.- The third part is dedicated to the evaluation of how efficient will such devices be while functioning at cryogenic temperature. A theoretical quantification of the optomechanical coupling that these cavities might reach is also presented
Temperature coefficients of crystalline-quartz elastic constants over the cryogenic range [4âK, 15âK]
Frequency-Temperature Compensated Cuts of Crystalline-Quartz Acoustic Cavity Within the Cryogenic Range [4 K, 15 K]
International audienceNew temperature-coefficients of quartz elasticcoefficients particularly relevant at liquid-helium temperature have been reported recently. Based on this result, frequencytemperature compensated cuts are predicted by calculation, and then demonstrated by experiment. Such compensated cuts can definitely fix the issue of remaining temperature sensitivity of crystalline quartz acoustic cavities unbeatable for their extremely low mechanical loss, as low as 10â9, when operated at liquid-He temperature
Temperature Coefficients of Quartz at Cryogenic Temperature
International audienceThe temperature coefficients of the elastic coefficients of quartz within [4 K, 15 K], the operating range of conventional cryocoolers, are predicted from experimental data. Raw data consist of a set of frequency-temperature curves recorded from bulk acoustic wave resonators made in different plates cut according to various angles relative to the crystallographic axes. Raw data are then processed as described in the paper in order to provide the 1st, 2nd, and 3rd order temperature coefficients of the seven elastic coefficients of quartz crystal