Patrice Feron

Université de Rennes 1 | UR1 · Laboratoire FOTON - Fonctions Optiques pour les Technologies de l'information

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 allow...

A variety of studies have been performed on WGM microresonators made of different materials and exploiting very high quality factors. This feature has allowed their use in a broad variety of applications including micro-lasers, optical filtering and switching, frequency conversion through non-linear effects, RF photonics and sensing. The easiest wa...

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We study from a theoretical point of view whispering gallery modes (WGM) in graded index micro-disk resonators where the refractive optical index varies with the radial position. Using a quantum mechanical analogy, we highlight three different behaviors for the WGM depending on the sign of a key parameter expressed as the ratio of the refractive in...

We investigate theoretically, in the frame of Coupled-Mode Theory (CMT), a system made of two laterally coupled, perfectly phase-matched, index-coupled Bragg waveguides, the modal gain of the amplifying one compensating exactly the modal losses of the other. Reverting to the supermode eigenbasis of the underlying “naked” (non-periodic) Parity-Time...

We report on an experimental study of a laser regime in erbium-doped whispering-gallery-mode (WGM) microspheres under modal-coupling between the co- and counterpropagating modes. The evidence of modal coupling is observed in the relative intensity noise spectrum of several WGM lasers. Cross-correlation measurements are carried out in order to analy...

We report on an experimental study of laser regime in erbium-doped whispering gallery mode (WGM) microspheres under modal-coupling between the co- and counter-propagating modes. The evidence of modal coupling has been observed in the relative intensity noise spectrum of several WGM lasers. Cross-correlation measurements have been carried out in ord...

Silica microspheres were coated using an erbium activated silica hafnia thin film in order to produce microlasers. Lasing was observed and the lasing modes were identified. Only the modes whose electric field is located closest to the surface were found to exhibit lasing.

We consider self-pulsing regimes in chains of Kerr nonlinear optical microresonators. By means of a supermodal diagonalization procedure of the conventional coupled-mode theory in time, we theoretically and numerically study the bifurcation diagrams of a singly pumped three-cavity and a doubly pumped four-cavity system: the latter allows us to pred...

We consider self-pulsing regimes in chains of Kerr non-linear optical micro-resonators. By means of a super-modal diagonalization procedure of the conventional coupled-mode theory in time, we theoretically and numerically study the bifurcation diagrams of a singly-pumped 3-cavity and a doubly-pumped 4-cavity systems: the latter allows us to predict...

An original method able to fully characterize high-Q resonators in add-drop configuration has been implemented. The method is based on the study of two cavity ringdown (CRD) signals, which are produced at the transmission and drop ports by wavelength sweeping a resonance in a time interval comparable with the photon cavity lifetime. All the resonat...

We investigate theoretically, in the frame of Coupled-Mode Theory, a Parity-Time Symmetric directional coupler inserted into a symmetric resonant cavity, all ports being terminated by four identical lossless reflectors. The scattering parameters are expressed under analytic closed forms in several equivalent bases, underlining the fact that PT Symm...

The relative intensity noise (RIN) of a solid state whispering-gallery-mode class-B laser is studied both theoretically and experimentally under different pumping regimes. In particular, we show that harmonics of the spiking frequency are observed in the RIN spectrum. A rate equation model including Langevin forces and the nonlinear coupling betwee...

We characterize a system consisting of a two-mode waveguide coupled to a single-mode microring resonator possibly presenting a nonlinear response of Kerr type. By using the scattering parameter formalism extended to the multimode domain, we show that in the linear regime and for an ideally transparent medium, each resonance of the system can be exp...

In terms of Linear Algebra, a directional coupler between a single-mode waveguide and a two-mode waveguide can be thought of as formally equivalent to a set of three mutually coupled single-mode waveguides. Its responses, easily derived in the frame of ternary Coupled-Mode Theory, are used to establish analytically the scattering parameters of a hy...

Ultrahigh-quality (Q) factor optical micro-resonators with very long photon storage time are important in the aim of integrating optical functions such as filters, tunable delay lines for microwave-photonics or highly sensitive sensor applications. To date, Q-factors up to 1011 have been measured only in millimetre-size crystalline whispering-galle...

We propose a novel phase-matching scheme in GaP whispering-gallery-mode microdisks grown on Si substrate combining modal and 4-quasi-phase-matching for second-harmonic-generation. The technique consists in unlocking parity-forbidden processes by tailoring the antiphase domain distribution in the GaP layer. Our proposal can be used to overcome the l...

GaP is a promising candidate for the development of highly integrated photonic functions on silicon, because of its quasi lattice-matching with Si and its interesting χ (2) non-linear properties. We here present the realization of GaP-based microdisks on Si substrates, and discuss their optical properties. Especially, emphasis is given on the impac...

Optical microcavities with ultralong photon storage times are of central importance for integrated nanophotonics. To date, record quality (Q) factors up to 1011 have been measured in millimetric-size single-crystal whispering-gallery-mode (WGM) resonators, and 1010 in silica or glass microresonators. We show that, by introducing slow-light effects...

We propose the use of a prism with nonlinear optical properties to improve the prism-coupling method. The principle is based on the inscription of an adapted waveguide inside this prism by beam self-trapping to enhance the coupling efficiency and stability. The experimental demonstration is realized with a prism diced from a LiNbO3 wafer to couple...

We report experimental results regarding the development of Er3+-doped glass microspherical cavities for the fabrication of compact sources at 1.55 μm. We investigate several different approaches in order to fabricate the microspheres including direct melting of Er3+-doped glass powders, synthesis of Er3+-doped monolithic microspheres by drawing Er...

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 configurati...

Two coupled microresonator systems with instantaneous nonlinear index can exhibit self-pulsing behavior and could be used as all-optical integrated microwave generators. The frequency of the RF signal is limited by the photon lifetime of the resonators. For oscillations at tens of GHz, semiconductor microdisks with moderate quality factors (≈10^4)...

The 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 nonlin...

The modal dispersion of a whispering gallery mode (WGM) resonator is a very important parameter for use in all nonlinear optics applications. In order to tailor the WGM modal dispersion of a microsphere, we have coated a silica microsphere with a high-refractive-index coating in order to study its effect on the WGM modal dispersion. We used Er3+ io...

Various resonators are investigated for microwave photonic applications. Micro-sphere, disk and fiber ring resonators were designed, realized and characterized. Obtained quality factors are as high as Q = 10^10.

The properties of whispering gallery modes (WGM) of a microsphere can be tailored by coating the resonator with a thin film. If the coating has a higher refractive index than the microsphere core, the resulting structure will have a configuration which has similarities both with a classical WGM resonator and with a planar waveguide. By choosing the...

Light coupling into a whispering-gallery mode resonator with a spatial soliton is demonstrated. Our setup, based on a LiNbO3 prism, features robustness, mode selectivity and single-mode propagation thanks to the nonlinear confinement.

We propose an original method to couple light into a whispering-gallery mode resonator. This method benefits from the mode selectivity and robustness of the prism-coupling along with the single-mode propagation of the fiber taper. It consists in a prism shaped crystal with a waveguide inscribed inside it. The waveguide is self-inscribed in-situ by...

We present some results regarding the coating of spherical microresonators and their different applications in photonics. The spherical microresonators high Q-factor and low mode volume make them perfect for a number of photonics applications. A thin film coating on the surface of the resonator using an optically active or passive layer can be used...

Ultrahigh-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 qu...

We improve theoretically and experimentally the problem of the coupling between a high Q-factor resonator and its external coupler. We have observed oscillations of ringing induced by the sweeping of the excitation frequency of an active microsphere. Thanks to this approach, the quality factor of an optical resonator was measured and we obtained Q...

Coatings of spherical optical microresonators are widely employed for different applications. Here the effect of the thickness of a homogeneous coating layer on the coupling of light from a tapered fiber to a coated microsphere has been studied. Spherical silica microresonators were coated using a 70SiO₂ - 30HfO₂ glass doped w...

We report experimental results on the characterization of microspherical cavities fabricated in Er3+-doped modified-silica and phos- phate glasses. The spectroscopic properties of the bulk precursor glasses as compared to the obtained microspheres were investigated by photoluminescence spectroscopy and lifetime measurement for the 4I13/2 ! 4 I15/2...

Spherical microresonators were coated using a 70SiO2 - 30HfO2 glass doped with 0.3 mol% Er3+. The sphere was characterized by coupling a 1480 nm pump laser inside the sphere using a tapered optical fiber and observing the 1530-1580 nm Er3+ emission outcoupled with the same tapered fiber. The measurements were done for different coating thicknesses...

We study both theoretically and experimentally the dispersive properties of single whispering gallery mode resonators. We present a simple experimental protocol which allows us to obtain in detail its coupling regime and thus their dispersive properties. We demonstrate a compact optical amplifier with a gain up to 20dB in an Erbium doped fluoride m...

Glass ceramic activated by rare earth ions are nanocomposite systems that exhibit specific morphologic, structural and spectroscopic properties allowing to develop interesting new physical concepts, for instance the mechanism related to the transparency, as well as novel photonic devices based on the enhancement of the luminescence. At the state of...

We experimentally demonstrate a compact optical amplifier consisting of a rare-earth-doped whispering-gallery-mode microsphere coupled via a tapered fiber. A gain up to 20 dB is reported in an erbium-doped fluoride glass microsphere 135 μm in diameter. Below the amplification regime, the optical gain is used to compensate for unavoidable losses due...

Silica microspheres were made by melting the tip of a standard telecom fiber. They were coated using a dip coating apparatus with a 70% SiO2 - 30 HfO2 sol-gel derived glass activated by 0.3 % mol of Er3+. The whispering gallery modes of the coated resonator were studied using a full taper - microsphere coupling setup. Upon excitation at 1480 nm sha...

Silica microspheres were made by melting the tip of a standard telecom fiber and were coated with a 70SiO2 - 30 HfO2 sol-gel derived glass activated by 0.3 mol % of Er3+ ions. The samples were coated using a dip coating apparatus. The thickness of the coating was estimated to be around 1 μm. The whispering gallery modes of the coated resonator were...

Coating of spherical microresonators is a very promising technique for optimizing their optical properties. Optical coatings are constituted by glasses, polymer, and glass ceramics, passive or activated by luminescent species, Glass ceramic activated by rare earth ions are nanocomposite systems that exhibit specific morphologic, structural and spec...

We show both theoretically and experimentally that the lifetime of an active semiconductor photonic crystal nanocavity is enhanced thanks to the combination of two cooperative effects: slow light propagation based on coherent-population-oscillation effect and optical bistability. In particular we develop an analytical analysis enabling us to clearl...

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Coupled nonlinear resonators have potential applications for the integration of multistable photonic devices. The dynamic properties of two coupled-mode nonlinear microcavities made of Kerr material are studied by linear stability analysis. Using a suitable combination of the modal coupling rate and the frequency detuning, it is possible to obtain...

A simple model is used to simulate the dynamic properties of coupled nonlinear microcavities. The model has been checked using a nonlinear finite difference time domain code. We show that two coupled nonlinear cavities with a Kerr nonlinearity can have multistable or self pulsing behaviors. Finally, an application as a positive pulse all-optical me...

Huge confinement of light over micro and nano structures is finding various applications in the field of photonics. In this letter the results obtained over two different kinds of confined structures viz., (i) Metallo-Dielectric colloidal structures (MDCS), obtained by immobilization of metallic gold (Au) nanoparticles on the dielectric silica netw...

We analyse the transient transmission response of a high quality (Q) factor whispering gallery mode resonator when the probe laser frequency is rapidly swept across the resonance. The detailed comparison with a simple numerical linear model allows the coupling regime and the strength of the intracavity Rayleigh scattering to be measured. By includi...

Confinement of light into small volumes has become an essential requirement for photonic devices; examples of this trend are provided by optical fibers, integrated optical circuits, semiconductor lasers, and photonic crystals. Optical dielectric resonators supporting Whispering Gallery Modes (WGMs) represent another class of cavity devices with exc...

Glass ceramic activated by rare earth ions are nanocomposite systems that exhibit specific morphologic, structural and spectroscopic properties allowing to develop interesting new physical concepts, for instance the mechanism related to the transparency, as well as novel photonic devices based on the enhancement of the luminescence. At the state of...

We present ringing phenomenon in coupled resonators and in high-Q amplifying whispering gallery mode resonators. This effect can be used to measure the gain and the group delay of optical integrated delay lines.

Dans cette communication nous présentons une étude théorique et expérimentale des effets dynamiques obtenus dans des microrésonateurs à modes de galerie passifs ou actifs. En particulier, nous analysons la réponse linéaire de ces systèmes lorsqu'ils sont excités à l'aide d'un signal dont la fréquence est modulée linéairement. Les résonateurs à haut...

We report on the observation of a compact optical microwave source based on a whispering gallery mode (WGM) laser. The use of a single 160-??m diameter erbium-doped glass microsphere and two half fiber tapers allows a dual single-mode laser emission around 1550 nm to be obtained. The generated beat note at 10.86 GHz has a linewidth of 22 kHz. This...

Whispering-gallery modes (WGM) on a spherical surface were first described by Lord Rayleigh at the beginning of the last century, but only after the invention of laser did they start to have some scientific relevance and only during the last two decades there has been a substantial move towards real devices and practical applications. WGM resonator...

We present a simple model to describe the transient response of two coupled resonators probed by a monochromatic wave whose frequency is rapidly swept across the resonances with respect to their characteristic photon lifetimes. The model is applied to analyze the dynamic behavior of the modal coupling between two degenerate resonances of the same c...

We theoretically analyze the light-storing process in optical microresonator arrays. We propose a passive and an active schemes to strongly slow light. The two mechanisms rely on microresonator chains whose high order dispersion is optimized. The unit cell of the systems is a short sequence of two or four resonators. In the passive process we show...

conference 7612 " Advances in Slow and Fast Light III ", Topic " Advanced Quantum and Optoelectronic Applications ", Session 7 " Slow Light in Microresonators and Semiconductor Structures " [7612-25], http://spie.org//x39144.xml

Silica spheres with diameters in the order of 100 µm were coated by Er³⁺-activated silica-hafnia films and then annealed in order to induce formation and growth of nanocrystals. The spectroscopic and morphologic properties of the spheres have been characterized by photoluminescence and atomic force microscopy techniques, respectively. Th...