Eric Picholle

Stabilization of a stimulated Brillouin fiber ring laser by strong pump modulation

A stable train of compressed Stokes pulses (to ~10 nsec) is obtained in a stimulated Brillouin fiber ring laser (of length L = 83 m) by periodically interrupting the argon-ion cw pump beam with an intraring cavity acousto-optic modulator. Interruption of the pump action, at each round-trip time tr ≃ Ln/c, permits damping of the excited sound waves that accumulate at the entry of the fiber owing to the inertial response of the material, well described by the coherent three-wave stimulated Brillouin scattering model (C3W-SBS equations). Amplification and compression of the backscattered Stokes pulse are limited by nonlinear optical Kerr effect, which is incorporated into the C3W-SBS equations.

Quantum photonics at telecom wavelengths based on lithium niobate waveguides

Integrated optical components on lithium niobate play a major role in standard high-speed communication systems. Over the last two decades, after the birth and positioning of quantum information science, lithium niobate waveguide architectures have emerged as one of the key platforms for enabling photonics quantum technologies. Due to mature technological processes for waveguide structure integration, as well as inherent and efficient properties for nonlinear optical effects, lithium niobate devices are nowadays at the heart of many photon-pair or triplet sources, single-photon detectors, coherent wavelength-conversion interfaces, and quantum memories. Consequently, they find applications in advanced and complex quantum communication systems, where compactness, stability, efficiency, and interconnectability with other guided-wave technologies are required. In this review paper, we first introduce the material aspects of lithium niobate, and subsequently discuss all of the above mentioned quantum components, ranging from standard photon-pair sources to more complex and advanced circuits.

Guided-acoustic-wave resonances in the dynamics of a stimulated Brillouin fiber ring laser

Abstract We observe the occurrence of several longitudinal modes in a stimulated Brillouin backscattering fiber ring laser operating in the unstable transition region between the stable cw and pulsed quasi-solitonic regimes. High order modes are preferentially excited, indicating a coupling between the two Brillouin processes in fibers, SBS and the guided-acoustic-wave Brillouin scattering (GAWBS).

Soliton compression and locking in a Brillouin fiber ring laser

ABSTRACT Stimulated Brillouin scattering (SBS) in an optical fiber cavity resonantly couples an optical cw-pump anda backscattered Stokes wave with electrostrictively excited longitudinal GHz hypersound waves. Below a crit-ical feedback the Stokes wave self-structurates into ns pulses, called Brillonin dissipative three-wave solitons; they are able in turn to electrostrictively excite lower frequency acoustic waves (f = 5 MHz to 1 GHz), dueto cladding Brillouin scattering (CBS), transversally propagating with respect to the fiber axis in the fiberscladding. We derive a four-wave model which couples the transverse CBS dynamics to the nonlinear dissipative three-wave SBS dynamics. Above a critical coupling, the resonant CBS oscillations (f/FSR = integer) arestrong enough to break the pulses, while stable compressed or decompressed pulses are still obtained in finitefrequency ranges between resonant frequencies: the small damped low frequency CBS vibrations contribute tolock further longitudinal cavity modes which compose the compressed SBS soliton. A stability map is computed.Compression up to a factor 0.4 with respect to the bare Brillouin soliton is numerically obtained, yielding nspulses of peak intensity up to 14 times the cw launched pump, in fair quantitative agreement with experimentsdone in long fiber ring cavities.Keywords : Stimulated Brillouin scattering, dissipative solitons, fiber ring lasers, pulse compression

A coherent approach to stationary stimulated Brillouin fiber amplifiers

An analytical stationary solution is proposed for the collinear Brillouin fiber mirror in the frame of the 1-D-coherent 3-wave model, in which decoupled phases allow side-resonance interaction, the conservation of the impulsion being insured by a nonlinear phase gradient. The Lorentzian shape of the gain curve of low efficiency stationary SBS amplifiers is then justified, even when the interaction is strong enough to stimulate an acoustic wave with a narrow spectral width. It is shown that, when SBS efficiency increases, the gain curve first exhibits some gain narrowing, then saturates, yielding for high pump powers a spectral band larger than the spontaneous Brillouin bandwidth.RésuméUne thé orie gé né rale de l’amplification Brillouin en régime stationnaire, est pré senté e qui tient compte à la fois de la déplétion de la pompe et d’un é ventuel dé saccord en fré quence du signal par rapport à la ré sonance. Cette é tude impose une ré interpré tation de la notion de largeur de gain Brillouin, l’amplificateur se comportant comme l’é quivalent acoustique d’un laser lorsque les ondes ré trodiffusée et maté rielle sont l’une et l’autre stimulées. On est alors en pré sence de trois ondes (pompe-Brillouin-acoustique), spectralement très é troites et donc de fré quences et de phases bien définies; en ré gime stationnaire, on peut se ramener à un système d’ é quations où les intensités sont indépendantes des phases, le dé saccord de fré quence é ventuel des trois ondes par rapport à la ré sonance é tant compensé par un gradient de phase longitudinal stationnaire. La largeur spectrale d’un amplificateur Brillouin peut ici être dé finie comme celle de la courbe de gain obtenue en faisant varier la fré quence d’un signal Stokes monochromatique autour de la résonance. Cette nouvelle dé finition n’affecte pas l’évolution de la ré ponse spectrale de l’amplificateur en fonction de la puissance. Dans la limite des gains faibles, on retrouve ainsi la lorentzienne associée à la diffusion spontanée, de même que son affinement par le gain. Puis, ce gain saturant à la résonance à une valeur correspondant à un transfert d’énergie presque total de la pompe vers l’onde Stokes, la courbe de gain recommence à s’ élargir, menant pour les très fortes puissances de pompe à une bande plus large que celle de la diffusion Brillouin spontanée.

Hopf Bifurcation in CW - Pumped Fiber Resonators: Generation of Stimulated Brillouin Solitons

Stimulated Brillouin scattering (SBS) in cw-pumped fiber lasers yield either steady or pulsed regimes. Stability analysis with general recoupling conditions allows the explanation of both regimes. The instantaneous acoustic response model proves to be singular, while the coherent SBS three-wave model yields a well behaved Hopf bifurcation taking as control parameter, either the feedback R for a given SBS gain L, or L for a given R. For a pump intensity above the SBS threshold, and not depending on the initial conditions, the nonlinear 3-W dynamics yields both asymptotic regimes: for a feedback R > R crit (of some percent in intensity) the backscattered Stokes wave evolves towards the steady mirror regime, and for R < R crit morphogenesis of a stable train of Brillouin “soliton-like” pulses takes place. Numerical simulations including optical Kerr perturbation and new experiments in an optical fiber-ring cavity support the bifurcation.

Dynamic Brillouin Processes in Fibers

The influence of the finite acoustic damping time on Stimulated Brillouin Scattering (SBS) has recently been experimentally emphasized in optical fibers (chaos,SBS-solitons, etc.). This paper reviews those characteristic dynamical features, and sorts out the situation where the popular intensity model of SBS is sufficient from those where a coherent 3-wave model is absolutely needed.

Dissipative superluminous Brillouin solitons in an optical-fiber ring cavity

Generation of large-scale spatio-temporal coherent structures caused by stimulated Brillouin backscattering of a narrow-band laser wave in a large-gain one-dimensional nonlinear medium is studied by comparing the numerical simulations and the analytical asymptotics of the three-wave resonant model to actual experiments in a single-mode optical-fiber. This comparison recently allowed us to predict [1] and to perform the first experimental observation [2] of the “superluminous” Brillouin soliton backward propagating with respect to the cw pump in an optical-fiber ring-cavity.

Quantum coherence in semiconductor microlasers

The buildup of the coherence of a Class-B semiconductor microlaser in the sub-threshold region is characterized by photon coincidence. Correlation values g(2)(0) > 2 confirm the key role of spatio-temporal dynamics in the photon statistics.

Characterization of the Nonlinear Response of Class B Microlasers in the Threshold Region

The nonlinear response of a Class-B semiconductor microlaser in the sub-threshold region is characterized through photon coincidence. Correlation values g(2)(0) > 3 confirm the key role of spatio-temporal dynamics in the photon statistics.