Stochastic resonance is a paradoxical phenomenon whereby a weak signal can be amplified by application of noise. Stochastic resonance occurs in a number of nonlinear systems, in neurobiology, mesoscopic physics, photonics, atomic physics, mechanics,... The classical picture of stochastic resonance involves the stochastic synchronisation of the motion of a fictious particle (representing the system's state) in a bistable potential subjected to a weak amplitude harmonic modulation (the input signal) and to amplitude noise. Stochastic amplification of the weak signal is revealed in the spectral amplification at the signal frequency for a non zero input noise strength.
We report on the observation of phase stochastic resonance in a nanomechanical, photonic crystal membrane with integrated electrical actuation. The nanomechanical oscillator is forced by a coherent driving signal which results in a bistable behavior. Bistability occurs in a bidimensional phase space since the system has a response in amplitude and in phase. We subject the oscillator to an additional slow phase modulation and to phase noise. We evidence a stochastic resonance phenomenon with amplification of the phase or amplitude response of the system for a non-zero input noise. Moreover, a theoretical analysis reveals that phase noise acts in a multiplicative fashion. This has important consequences on the optimal parameters for stochastic resonance to occur and explains the observed noise-induced detuning in the system. Phase stochastic resonance may have impact on several domains, including signal transmission telecommunication with coherent protocols such as Phase Shifting Keying, or metrology with improved detection.
Two-dimensional photonic crystal slabs (PCS) offer an appealing alternative to distributed Bragg reflectors or filters for various applications. Indeed, their scattering properties, governed by Fano-resonances, have been used in areas as diverse as optical wavelength and polarization filters, reflectors, semiconductor lasers, photodetectors, bio-sensors, or non-linear optical components. Suspended PCSs also find natural applications in the field of optomechanics, where the mechanical modes of a suspended slab interact via radiation pressure with the optical field of a high finesse cavity. The reflectivity and transmission properties of a defect-free suspended PCS around normal incidence can be used to couple out-of-plane mechanical modes to an optical field by integrating it in a free space cavity. We have demonstrated the successful implementation of a PCS reflector on a high-tensile stress Si3N4 nanomembrane. We could measure the photonic crystal band diagram with a spectrally, angular, and polarization resolved setup. Moreover, a cavity with a finesse as high as 12 000 was formed using the suspended membrane as end-mirror of a Fabry-Perot cavity. These achievements allow us to operate in the resolved sideband regime where the optical storage time exceeds the mechanical period of low-order mechanical drum modes. This condition is a prerequisite to achieve quantum control of the mechanical resonator with light.
Microphotoluminescence experiment has been performed on InAsP/InP epitaxial quantum dots,
emitting in the telecommunication wavelength range. The exciton emission from a single quantum
dot has been detected via the excitation power dependence of the microphotoluminescence spectra.
Two photon entanglement schemes are proposed in order to produce entangled photons out of the
excitonic and bexcitonic transitions in such dot. Both schemes require the implementation of Purcell
effect, in order to collect efficiently the emitted photons and to restore entanglement.
Single photon sources are of extreme interest for future quantum communications networks. Several realizations of such sources where proposed but none of them corresponds to the needs of a quantum network, in terms of emission wavelength, repetition rate or quantum state purity. Using self organized InAs/InP quantum dots, it is
possible to tune the emission wavelength up to 1.55 μm. Lifetime measurements confirm the high optical quality of these dots opening the possibility to engineer sources operate above 77K. With this material combination it is also possible to localized the growth of a single quantum dot, that can be to deterministically coupled to a
photonic crystal cavity.
Optical microcavities offer the ability to create extremely low-threshold lasers with high modulation bandwidth. In such microcavity devices, the fraction β of spontaneous emission into the lasing mode can become close to one and the step-like "threshold" gradually disappears. To implement such high-β devices, one can exploit Cavity Quantum ElectroDynamics effects, more precisely spontaneous emission enhancement. The concomitant effect of spontaneous emission acceleration is the preferential funnelling of spontaneous emission into the cavity mode. In our work, the cavity is a double- heterostructure cavity etched on a suspended membrane and contains InAs quantum dots. Lasing is achieved with β-factors higher than 0.44 and is sustained by less than 10 quantum dots.
Waveguides in photonic crystals are one-dimensional photonic systems, with a richer basic physics than micro/nanocavities thanks to their extended nature. We evidence various roles of the one-dimensional singularities that occur at zero-group velocity points dispersion relations and mode anticrossings: One role is the demultiplexing in a space-localized fashion, combining properties of the Fabry-Perot and grating dispersive devices in a miniature footprint. Various aspects of the realization of such devices will be presented, towards WDM or coarse WDM applications in the framework of the european FUNFOX project.
Another role is the possiblity to enhance gain in inverse proportion of the slwoed-down group velocity. A third possiblity is to produce a Purcell effect and thus a shorter lifetime for emitters embedded in such waveguides. This last possibility raises the prospect of an integrated high efficiency source with controlled photon modes.