Stable integrated hyper-parametric oscillator based on coupled optical microcavities

We propose a flexible scheme based on three coupled optical microcavities which permits to achieve stable oscillations in the microwave range, the frequency of which depends only on the cavity coupling rates. We find the different dynamical regimes (soft and hard excitation) to affect the oscillation intensity but not their period. This configuration may permit to implement compact hyper-parametric sources on an integrated optical circuit, with interesting applications in communications, sensing and metrology.Comment: 4 pages, 5 figure

Remise en forme de signaux à base de micro-résonateurs non-linéaires couplés

session Affiches, thème 1 " Systèmes et réseaux de télécommunications optiques " [A-Th1-10]National audienceNous proposons et testons de manière numérique un dispositif présentant une fonction de transfert non-linéaire permettant l'augmentation du rapport signal sur bruit dans les télécommunications optiques. Ce dispositif tout optique de remise en forme des impulsions est basé sur l'utilisation de micro-résonateurs présentant un effet Kerr non linéaire. Comme nous profitons de l'exaltation du champ électrique à l'intérieur des résonateurs, ce dispositif pourrait être sensiblement plus réduit que les dispositifs basés sur des fibres optiques ou des guides d'onde plus conventionnels

Controlling single diamond NV color center photoluminescence spectrum with a Fabry-Perot microcavity

We present both theoretical and experimental results on fluorescence of single defect centers in diamond nanocrystals embedded in a planar dielectric microcavity. From a theoretical point of view, we show that the overall fluorescence collection efficiency using moderate numerical aperture microscope objective can be enhanced by using a low quality factor microcavity. This could be used in particular for low temperature applications where the numerical aperture of collection microscope objectives is limited due to the experimental constraints. We experimentally investigate the control of the fluorescence spectrum of the emitted light from a single center. We show the simultaneous narrowing of the room temperature broadband emission spectrum and the increase of the fluorescence spectral density.Comment: 22 pages, 10 figure

High-Q Whispering-Gallery-Modes Microresonators in the Near-Ultraviolet Spectral Range

High-$Q$ whispering gallery mode microresonators are cornerstones to develop compact coherent sources like single frequency lasers or frequency combs. This work reports a detailed characterization of a whispering gallery mode microsphere in the near ultraviolet. Light coupling in the resonator is obtain thanks to a robust angle-polished fiber allowing to investigate the different coupling regimes. An intrinsic $Q_0$-factor of $2.2 \times 10^8$ and a finesse of $7.3 \times 10^4$ are reported at a wavelength of 420 nm. Physical mechanisms contributing to the $Q_0$-factor are discussed and routes to improve the performances are drawn. Such high-$Q$ factor and high finesse are key ingredients to ease the study of photonic devices based on WGM microresonators.Comment: 6 pages, 6 figure

Études expérimentales de dispositifs intégrés à base de micro-résonateurs à mode de galerie en verres actifs

Les microrésonateurs à mode de galerie passifs à base de cristal ou de verre fabriqués par la méthode de fusion possèdent un facteur de qualité limité à quelques 10E8. Ceci est généralement dû à la contamination de la surface du résonateur lors de sa fusion. Dans ces travaux, nous proposons de contourner cette limitation en utilisant des microrésonateurs actifs pour compenser les pertes. Afin de caractériser les microrésonateurs actifs de très haut facteur de qualité ainsi obtenu, nous nous appuyons sur la méthode CRDM (Cavity Ring Down Measurement). Cette méthode interférométrique est d'une part bien adaptée à la caractérisation de résonateurs de très haut facteur de qualité et d'autre part elle permet de remonter de manière univoque aux facteurs de qualité intrinsèque Qo et extrinsèque Qe du résonateur. Dans un régime de compensation de pertes, nous avons pu atteindre tous les régimes de couplage et obtenus des facteurs de qualité intrinsèques excédant les 10E10. En régime d'amplification sélective, nous avons démontré expérimentalement que l'on pouvait obtenir des gains élevés allant jusqu'à 33 dB et des retards de groupe excédant 2,3 s dans ces microrésonateurs actifs. Ces microrésonateurs de très haut facteur de qualité et de très haute finesse peuvent présenter un couplage modal se manifestant par un doublet de résonances. Une confrontation théorie/expérience avec la méthode CRDM permet de mesurer un écart très faible entre les doublets. Par ailleurs, ces microrésonateurs présentant un fort confinement spatial et une forte surtension, sont propices à l'observation d'effets non-linéaires. Une modélisation intégrant l'effet thermique et l'effet Kerr a été réalisée. Une confrontation théorie/expérience nous a permis d'estimer la puissance réellement injectée dans le mode ainsi qu'à estimer le volume du mode.Glass-based whispering gallery mode (WGM) microresonators are easy to produce by melting techniques. However, they suffer from surface contamination which limits their long term quality factor to only about 10E8. In this thesis, we show that an optical gain provided by erbium ions can compensate for residual losses. The optical characterization method is based on frequency-swept Cavity-Ring-Down-Measurement . This method can fully describe the linear properties of microcavities such as coupling regime and group delay. In compensation loss regime we demonstrate that it is possible to control the coupling regime of an ultrahigh Q-factor microresonator from undercoupling to spectral selective ampli cation. Under the selective amplification regime, we obtain an internal Q-factor exceding 10E10. In selective amplification, we experimentally show that it is possible to obtain high amplification up to 33 dB and a high group delay. The microresonators with high Q-factor and high finesse could give rise to a modal coupling which exhibits a splitting of the resonance in the transmission. A characterization of this phenomenon with the cavity ring down method was realized. Moreover, these microresonators, are conducive to the non-linear effect observation. A model incorporating the thermal effect and the Kerr effect has been achieved. Confrontation between theory and experiment allowed us to estimate the real optical power injected into the mode as well as estimating the mode volume.RENNES1-Bibl. électronique (352382106) / SudocSudocFranceF

Analysis of third-order nonlinearity effects in very high-Q WGM resonator cavity ringdown spectroscopy

International audienceThe time domain coupled-mode theory (CMT) is applied to the analysis of the dynamic of third-order optical nonlinear effects in high-finesse whispering-gallery-mode (WGM) resonators. We show that this model is well adapted to the analysis of cavity-ringdown spectroscopy signal under modal-coupling due to Rayleigh backscattering in linear and nonlinear regimes. The experiments are carried out in silica WGM microspheres. Considering thermal and Kerr effects, CMT simulations are in good agreement, with experimental results for input power up to about 1 mW. For well-known optical materials such as silica, this experimental data analysis method can be used to measure the quality factor, the coupling regime, and the mode volume of high-finesse WGM. Furthermore, this technique could be developed to infer linear and nonlinear properties of high-finesse coated WGM microspheres

Microcavity-quality-factor enhancement using nonlinear effects close to the bistability threshold and coherent population oscillations

9 pagesInternational audienceWe analytically show that inserting a driven, two-level system inside a microcavity can improve its optical properties. In this approach, the strong dispersion induced by a pump via population oscillations increases the cavity lifetime experienced by a slightly detuned probe. We further predict that if the cavity is pumped through a resonant channel, optical absorptive or dispersive bistability can be combined with the population-oscillation-induced steep material dispersion to obtain a strong quality-factor enhancement. Moreover, differential amplification coming from the nonlinear feature of the pump transfer function can be used to drastically increase the probe transmission beyond intrinsic characteristics of the resonator. The Q-factor enhancement and the differential amplification can be advantageously combined with a frequency pulling effect to stabilize or readjust the microcavity resonance frequency

Magnetometry with nitrogen-vacancy ensembles in diamond based on infrared absorption in a doubly resonant optical cavity

We propose to use an optical cavity to enhance the sensitivity of magnetometers relying on the detection of the spin state of high-density nitrogen-vacancy ensembles in diamond using infrared optical absorption. The role of the cavity is to obtain a contrast in the absorption-detected magnetic resonance approaching unity at room temperature. We project an increase in the photon shot-noise limited sensitivity of two orders of magnitude in comparison with a single-pass approach. Optical losses can limit the enhancement to one order of magnitude which could still enable room temperature operation. Finally, the optical cavity also allows to use smaller pumping power when it is designed to be resonant at both the pump and the signal wavelength

Controling the coupling properties of active ultrahigh-Q WGM microcavities from undercoupling to selective amplification

International audienceUltrahigh-quality (Q) factor microresonators have a lot of applications in the photonics domain ranging from low-threshold nonlinear optics to integrated optical sensors. Glass-based whispering gallery mode (WGM) microresonators are easy to produce by melting techniques, however they suffer from surface contamination which limits their long-term quality factor to a few 10^8 . Here we show that an optical gain provided by erbium ions can compensate for residual losses. Moreover it is possible to control the coupling regime of an ultrahigh Q-factor three port microresonator from undercoupling to spectral selective amplification by changing the pumping rate. The optical characterization method is based on frequency-swept cavity-ring-down- pectroscopy. This method allows the transmission and dispersive properties of perfectly transparent microresonators and intrinsic finesses up to 4.0x10^7 to be measured. Finally we characterize a critically coupled fluoride glass WGM microresonator with a diameter of 220 mm and a loaded Q-factor of 5.3x10^9 is demonstrated

Time-domain analysis of resonator array buffers

International audienceWe present design and time-domain simulations of microresonator array optical delay lines. The proposed buffer consists of an n times m microresonator array unidirectionally coupled via a straight bus waveguide. We show that the use of a two-dimensional arrangement of resonators can compensate for the high order of dispersion and more specifically the third-order dispersion. Numerical calculations confirm that pulses can be stored in microresonator arrays without appreciable distortion. Finally, we briefly describe the detrimental effects of optical losses and technological errors