Michel Mortier

Millisecond Photon Lifetime in a Slow-Light Microcavity.

Optical microcavities with ultralong photon storage times are of central importance for integrated nanophotonics. To date, record quality (Q) factors up to 10^{11} have been measured in millimetric-size single-crystal whispering-gallery-mode (WGM) resonators, and 10^{10} in silica or glass microresonators. We show that, by introducing slow-light effects in an active WGM microresonator, it is possible to enhance the photon lifetime by several orders of magnitude, thus circumventing both fabrication imperfections and residual absorption. The slow-light effect is obtained from coherent population oscillations in an erbium-doped fluoride glass microsphere, producing strong dispersion of the WGM (group index n_{g}∼10^{6}). As a result, a photon lifetime up to 2.5xa0ms at room temperature has been measured, corresponding to a Q factor of 3×10^{12} at 1530xa0nm. This system could yield a new type of optical memory microarray with ultralong storage times.

Miniaturized Optical Microwave Source Using a Dual-Wavelength Whispering Gallery Mode Laser

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 preliminary experimental demonstration shows the potentialities of erbium-doped WGM resonators for microwave generation.

Micrometer-sized point temperature sensor in Er:ZBLALiP

A new kind of Erbium-doped heavy fluoride glass Er:ZBLALiP was elaborated, and microspheres were fabricated with this fluoride glass. Thermal properties and spectroscopic properties of Er:ZBLALiP excited at 805 nm were investigated. Based on this thermalization effects between upper levels of green fluorescence in Er:ZBLALiP, we proposed an optical temperature sensing using micrometer-sized spherical cavity. The sphere temperature is scaled by the ratio of green emission intensities at 522 and 547 nm. A wide dynamic temperature ranging from 100 K to 850 K can be utilized by this type of point temperature sensor.

Relative intensity noise in Er:ZBLALiP whispering gallery mode laser: theory and experiments (Conference Presentation)

Relative Intensity Noise in Er:ZBLALiP Whispering Gallery Mode Laser : Theory and ExperimentsnnPatrice Feron(1)*, Jean-Baptiste Ceppe(1,2), Michel Mortier(3), Yannick Dumeige(1).nn(1) CNRS, UMR 6082 Foton, Enssat, 6 rue de Kerampont, CS 80518, 22305 Lannion, France.n(2) IRCICA (CNRS USR 3380) - PhLAM (CNRS UMR 8523), 50 Avenue du Hallay, 59650 Villeneuve dAscq, Francen(3) IRCP (CNRS-UMR 8247), Chimie-Paristech, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05, France.n*corresponding author patrice.feron@enssat.fr +33296469042nceppe@enssat.fr +33359632258ndumeige@enssat.fr +33296469110nmichel-mortier@chimie-paristech.fr+33153737927nEPE113nFiber Lasers and Glass Photonics: Materials through Applications nFibers and Waveguide Sources – metrology and testing methods for laser sourcesn nAbstract:nMicro spherical resonators have attracted significant attention in recent years due to their interesting optical properties and the range of applications for which they can be used. Most of the publications dedicated to micro spherical Laser are devoted to lasing effects in different materials where the spectral properties of the emission depends on (i) the choice of dopant (e.g. Er3+, Yb3+, Tm 3+) and (ii) the host matrix (e.g. silica, fluoride, phosphate or telluride glass) in which the dopant is embedded. Yet, the dynamics of theses Lasers are still to be studied. This paper shows experimental and theoretical results on the amplitude fluctuations of a Whispering Gallery Mode Laser, also known as relative intensity noise (RIN). It gives information about the dynamics inside the cavity, such as photon lifetime, effective pumping rate and noise sources. We use as active medium Er3+ doped fluoride ZBLALiP glass. Theses glasses are well adapted to the development of micro spherical Laser operating in the infrared region, in particular with emission wavelengths falling respectively in the C-band. nIn this paper we report on the RIN measurements for several pumping configurations of Erbium doped fluoride glass WGM micro-lasers. Due to the unique properties of WGM resonators, harmonics of the spiking frequency are observed in the RIN spectrum. Usual model of class B laser has been extended to take into account WGM specificities in order to exploit the experimental results. The model including nonlinear coupling of population inversion and photon number fluctuations is well suited for the description of low mode volume WGM lasers for which this coupling is not negligible. The comparison between experiments and our model allow relevant physical parameters to be extracted from the fitting of the RIN spectrum (as example mode volume and quantum numbers of the WGM). Our approach could be extended to WGM laser frequency noise and exploited in the analysis of the whole noise properties of micro-lasers used in sensor applications.

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

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

High gain selective amplification in whispering gallery mode resonators: analysis by cavity ring down method

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 microsphere of 135μm in diameter coupled via a tapered fiber. The model is also applied to analyze the dynamic behavior of the modal coupling between two degenerate resonances of the same cavity. In particular, this can be used to describe the coupling of counterpropagating whispering gallery modes (WGM) by Rayleigh scattering. The theory is successfully compared to experiments carried out in silica microspheres

Red-shift due to pump intensity in Er:ZBLALiP whispering-gallery mode lasers

A new kind of Erbium doped heavy fluoride glass Er:ZBLALiP has been studied. Microspheres were fabricated with this fluoride glass. Whispering Gallery Mode laser spectra around 1550 nm were analyzed for different sphere diameters and Erbium concentrations (from 0.01% to 0.2% by mole) under pumping by a fiber taper at 1480 nm. Red-shift effect on the frequencies of both fluorescence and laser spectra is experimentally observed when the pump power is increased, originating from thermal effects. A spectroscopic technique based on the green upconversion fluorescence is used to compute a loading effective temperature for the Er:ZBLALiP microsphere and this further allows us to calibrate the properties of the microsphere laser in terms of the thermal expansion as well as the variation of the refractive index.