Cavity-enhanced room-temperature magnetometry using absorption by nitrogen-vacancy centers in diamond

We demonstrate a cavity-enhanced room-temperature magnetic field sensor based on nitrogen-vacancy centers in diamond. Magnetic resonance is detected using absorption of light resonant with the 1042 nm spin-singlet transition. The diamond is placed in an external optical cavity to enhance the absorption, and significant absorption is observed even at room temperature. We demonstrate a magnetic field sensitivity of 2.5 nT/sqrt(Hz), and project a photon shot-noise-limited sensitivity of 70 pT/sqrt(Hz) for a few mW of infrared light, and a quantum projection-noise-limited sensitivity of 250 fT/sqrt(Hz) for the sensing volume of 90 um x 90 um 200 um.Comment: main text 5 pages, supplementary material 3 page

Experimental open air quantum key distribution with a single photon source

We present a full implementation of a quantum key distribution (QKD) system with a single photon source, operating at night in open air. The single photon source at the heart of the functional and reliable setup relies on the pulsed excitation of a single nitrogen-vacancy color center in diamond nanocrystal. We tested the effect of attenuation on the polarized encoded photons for inferring longer distance performance of our system. For strong attenuation, the use of pure single photon states gives measurable advantage over systems relying on weak attenuated laser pulses. The results are in good agreement with theoretical models developed to assess QKD security

Nonlinear Bloch modes, optical switching and Bragg solitons in tightly coupled micro-ring resonator chains

We study nonlinear wave phenomena in coupled ring resonator optical waveguides in the tight coupling regime. A discrete model for the system dynamics is put forward and its steady state nonlinear Bloch modes are derived. The switching behavior of the transmission system is addressed numerically and the results are explained in the light of this analytical result. We also present a numerical study on the spontaneous generation of Bragg solitons from a continuous-wave input.Comment: Final versio

Whispering gallery microresonators for second harmonic light generation from a low number of small molecules

Unmarked sensitive detection of molecules is needed in environmental pollution monitoring, disease diagnosis, security screening systems and in many other situations in which a substance must be identified. When molecules are attached or adsorbed onto an interface, detecting their presence is possible using second harmonic light generation, because at interfaces the inversion symmetry is broken. However, such light generation usually requires either dense matter or a large number of molecules combined with high-power laser sources. Here we show that using high-Q spherical microresonators and low average power, between 50 and 100 small non-fluorescent molecules deposited on the outer surface of the microresonator can generate a detectable change in the second harmonic light. This generation requires phase matching in the whispering gallery modes, which we achieved using a new procedure to periodically pattern, with nanometric precision, a molecular surface monolayer

Stable integrated hyper-parametric oscillator based on coupled optical microcavities

We propose a flexible scheme based on three coupled optical microcavities that permits us to achieve stable oscillations in the microwave range, the frequency of which depends only on the cavity coupling rates. We find that the different dynamical regimes (soft and hard excitation) affect the oscillation intensity, but not their periods. This configuration may permit us to implement compact hyper-parametric sources on an integrated optical circuit with interesting applications in communications, sensing, and metrology. (C) 2015 Optical Society of Americ

Génération de second harmonique accordée en phase dans les cristaux photoniques en semiconducteur III-V à géométrie verticale

Nous avons observé la génération de second harmonique accordée en phase dans une structure périodique constituée d'A1$_{30\%}$Ga$_{70\%}$As et d'AlOx. D'une part l'accord de phase est réalisé en utilisant le fait que la dispersion du cristal photonique ainsi constitué est suffisante pour compenser la dispersion naturelle du matériau semi-conducteur. D'autre part la localisation du champ électrique à l'intérieur de la structure permet une augmentation de l'efficacité de conversion

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

Chinese Scholar Committee (CSC); Centre National d'Etudes Spatiales [60281/00]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-mu 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