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Temporal Kerr cavity solitons are pulses of light that can persist in coherently-driven, dispersive resonators with Kerr-type nonlinearity. It is widely accepted that such solitons react to parameter inhomogeneities by experiencing a temporal drift whose rate is governed by the gradient of the parameter at the soliton's position. This result, however, assumes that the gradient of the inhomogeneity is constant across the soliton, which may not hold true under all situations, e.g. when using bichromatic driving or in the presence of third-order dispersion that gives rise to an extended dispersive wave tail. Here we report on theoretical and numerical results pertaining to the behavior of dissipative temporal Kerr cavity solitons under conditions where parameter inhomogeneities vary nonlinearly across the width of the soliton. In this case, the soliton velocity is dictated by the full overlap between its so-called neutral mode and the parameter perturbation, which we show can yield dynamics that are manifestly at odds with the common wisdom of motion dependent solely upon the gradient of the inhomogeneity. We also investigate how the presence of third-order dispersion and the associated dispersive wave tail changes the motion induced by parameter inhomogeneities. We find that the dispersive wave tail as such does not contribute to the soliton motion; instead, higher-order dispersion yields counter-intuitive influences on the soliton motion. Our results provide new insights to the behavior of temporal cavity solitons in the presence of parameter inhomogeneities, and can impact systems employing pulsed or bichromatic pumping and/or resonators with non-negligible higher-order dispersion., 8 pages, 5 figures

We demonstrate a Kerr soliton dual-microcomb generation by synchronously driving two orthogonal polarization modes of a single microresonator. We also apply the generated dual-microcomb to perform a proof-of-concept spectroscopic measurement.

We investigate novel cavity solitons that arise in pulse-pumped fibre resonators in the presence of desynchronisation and stimulated Raman scattering. The solitons possess numerous advantageous characteristics and could enable novel route to ultrafast pulses.

We present an all-optical random number generator employing polarization symmetry-breaking in a nonlinear Kerr cavity. Statistically confirmed random numbers are generated at MHz rates without post-processing, paving the way for a novel coherent Ising machine.

We study the intermodal four-wave mixing interactions in a high-Q MgF2 microresonator, and show that such interactions can enable the generation of visible and infrared sidebands spaced by more than 150 THz from the pump.

A two-mode Kerr cavity with a π-phase defect exhibits a virtual Möbius topology and enables spontaneous symmetry breaking with unprecedented robustness. Experiments performed with homogeneous and localized states confirm our predictions.

We present an all-optical random number generator based on polarization symmetry breaking in a passive, nonlinear Kerr cavity. The system generates numbers with statistically confirmed randomness at MHz rates with no post-processing.

We explore the dynamics of temporal cavity solitons under rapid parameter inhomogeneities where usual linear approximations become invalid. We show that a more general theoretical treatment allows for the accurate prediction of soliton motion.

Parametric oscillation in Kerr microresonators provides an attractive pathway for the generation of new optical frequencies in a low-power, small-footprint device. The frequency shift of the newly generated parametric sidebands is set by the phasematching of the underlying four-wave-mixing process, with the generation of large frequency shift sidebands typically placing exacting requirements on a resonator’s dispersion profile. In practice, this limits the range of viable pump wavelengths, and ultimately the range of output frequencies. In this paper, we consider a multimode four-wave-mixing process in which the pump and sidebands propagate in different mode families of the resonator. We show that this multimode configuration yields a considerable relaxation in the phasematching requirements needed to generate large frequency shift parametric sidebands, allowing their formation even in resonators with strong second-order dispersion. Experimentally we use a magnesium-fluoride micro-disk resonator to demonstrate this multimode phasematching. By accessing different pump and sideband modes, four distinct multimode parametric processes generating frequency shifts between 118 and 216 THz are reported. The resulting separation between the two sidebands is almost three octaves.

Soliton microresonator frequency combs (microcombs) have recently emerged as an attractive new type of optical comb source with a wide range applications proposed and demonstrated. To extend the optical bandwidth of these microresonator sources, several previous studies have proposed and studied the injection of an additional optical probe wave into the resonator. In this case, nonlinear scattering between the injected probe and the original soliton enables the formation of new comb frequencies through a phase-matched cascade of four-wave mixing processes. In this work, we expand the relevant analyses to consider soliton–linear wave interactions when the soliton and the probe fields propagate in different mode families. We obtain an expression for the phase-matched idler locations as a function of the dispersion of the resonator and the phase detuning of the injected probe. We confirm our theoretical predictions in experiments performed in a silica waveguide ring microresonator.

The nonlinear scattering of a linear optical wave from a conservative soliton has been widely studied in optical fibers as a mechanism for nonlinear frequency conversion. Here we extend this analysis to consider the scattering of an externally injected probe wave from a dissipative Kerr cavity soliton circulating in a Kerr microresonator. We demonstrate, both theoretically and experimentally, that this nonlinear interaction can be harnessed for useful expansion of the soliton frequency comb via the formation of a secondary idler comb. We explore the physics of the process, showing that the phase detuning of the injected probe from a cavity resonance plays a key role in setting the central frequency of the idler comb, thus providing a convenient parameter through which to control the spectral envelope of that comb. Our results elucidate the dynamics that govern the interactions between dissipative Kerr cavity solitons and externally injected probe waves, and could prove useful in the design of future Kerr frequency comb systems by enabling the possibility to provide high-power comb lines in a specified spectral region simply through the injection of a suitably chosen probe., 7 pages, 5 figures

Modulation instability (MI) in the presence of noise typically leads to an irreversible and complete disintegration of a plane wave background. Here we report on experiments performed in a coherently driven nonlinear optical resonator that demonstrate nonlinear localization of dissipative MI: formation of persisting domains of MI-driven spatiotemporal chaos surrounded by a stable quasi-plane-wave background. The persisting localization ensues from a combination of bistability and complex spatiotemporal nonlinear dynamics that together permit a locally induced domain of MI to be pinned by a shallow modulation on the plane wave background. We further show that the localized domains of spatiotemporal chaos can be individually addressed---turned on and off at will---and we explore their transport behavior as the strength of the pinning is controlled. Our results reveal new fundamental dynamics at the interface of front dynamics and MI, and offer a route for tailored patterns of noiselike bursts of light.

Microcombs—optical frequency combs generated in coherently driven nonlinear microresonators—have attracted significant attention over the last decade. The ability to generate two such combs in a single resonator device has, in particular, enabled a host of applications from spectroscopy to imaging. Concurrently, novel comb generation techniques such as synchronous pulsed driving have been developed to enhance the efficiency and flexibility of microcomb generation. Here, we report on the first, to the best of our knowledge, experimental demonstration of dual-microcomb generation via synchronous pulsed pumping of a single microresonator. Specifically, we use two electro-optically generated pulse trains derived from a common continuous wave laser to simultaneously drive two orthogonal polarization modes of an integrated silica ring resonator, observing the generation of coherent dissipative Kerr cavity soliton combs on both polarization axes. Thanks to the resonator birefringence, the two soliton combs are associated with different repetition rates, thus realizing a dual-microcomb source. To illustrate the source’s application potential, we demonstrate proof-of-concept spectroscopic measurements.

Recent experiments have demonstrated that Kerr cavity solitons (CSs) and corresponding optical frequency combs can display novel dynamics and characteristics under conditions of near-zero-dispersion driving [1] , [2] . Whilst experimental studies have focused on stable CSs, theoretical studies have revealed that near-zero-dispersion conditions can also affect CS instabilities. In particular, breathing zero-dispersion CSs have been predicted to emit polychromatic dispersive waves [3] – in stark contrast to the sharp spectral peak that accompanies a stable CS. Furthermore, the presence of strong third-order dispersion has been theoretically proposed to impact on the range of parameters over which CSs are unstable and exist [4] . However, no experimental studies have yet confirmed these predictions. In this work, we experimentally demonstrate the interplay between CS breathers and dispersive waves, and we experimentally study the impact of third-order dispersion on CS instabilities.

We report on how a π-phase defect in a two-mode Kerr cavity leads to flip-flopping dynamics and self-symmetrization, enabling spontaneous symmetry breaking with unprecedented robustness. Experiments performed with homogeneous and localized states confirm our predictions.

Kerr combs are demonstrated in a purely normal dispersion pulse-driven fiber mini-resonator. Though harmonic driving and tunable desynchronization, we are able to control both the spectral extents and line spacing of the output comb.

Kerr microresonators driven in the normal dispersion regime typically require the presence of localized dispersion perturbations, such as those induced by avoided mode crossings, to initiate the formation of optical frequency combs. In this work, we experimentally demonstrate that this requirement can be lifted by driving the resonator with a pulsed pump source. We also show that controlling the desynchronization between the pump repetition rate and the cavity free-spectral range (FSR) provides a simple mechanism to tune the center frequency of the output comb. Using a fiber mini-resonator with a radius of only 6 cm, we experimentally present spectrally flat combs with a bandwidth of 3 THz whose center frequency can be tuned by more than 2 THz. By driving the cavity at harmonics of its 0.54 GHz FSR, we are able to generate combs with line spacings selectable between 0.54 and 10.8 GHz. The ability to tune both the center frequency and frequency spacing of the output comb highlights the flexibility of this platform. Additionally, we demonstrate that under conditions of large pump-cavity desynchronization, the same cavity also supports a new, to the best of our knowledge, form of Raman-assisted anomalous dispersion cavity soliton.

We investigate theoretically and experimentally the instabilities of symmetry-broken, vectorial, bright cavity solitons (CSs) of two-mode nonlinear passive Kerr resonators. Through comprehensive theoretical analyses of coupled Lugiato–Lefever equations, we identify two different breathing regimes where the two components of the vectorial CSs breathe respectively in-phase and out-of-phase. Moreover, we find that deep out-of-phase breathing can lead to intermittent self-switching of the two components, spontaneously transforming a soliton into its mirror-symmetric state. In this process, solitons are also sometimes observed to decay. All our theoretical predictions are confirmed in experiments performed in an optical fiber ring resonator, where CS symmetry breaking occurs across the polarization modes of the resonator. To the best of our knowledge, our study constitutes the first experimental report of breathing instabilities of multi-component optical solitons of driven nonlinear resonators.

Dissipative Kerr cavity solitons are pulses of light that can persist in coherently driven nonlinear optical resonators. They have attracted significant attention over the past decade due to their rich nonlinear dynamics and key role in the generation of coherent microresonator optical frequency combs. Whilst the vast majority of implementations have relied on \emph{homogeneous} continuous wave driving, the soliton's "plasticity" combined with \emph{inhomogeneous} driving offers attractive advantages for a host of applications. Here we review recent studies into the dynamics and applications of Kerr cavity solitons in the presence of inhomogeneous driving fields. In particular, we summarise the salient theoretical developments that allow for the analysis of CS motion in the presence of pump phase or amplitude inhomogeneities, and survey recent experiments that use pulsed driving to realise energy efficient and flexible microresonator optical frequency combs., 19 pages, 5 figures, invited review article

Spontaneous symmetry breaking is central to our understanding of physics and explains many natural phenomena, from cosmic scales to subatomic particles. Its use for applications requires devices with a high level of symmetry, but engineered systems are always imperfect. Surprisingly, the impact of such imperfections has barely been studied, and restricted to a single asymmetry. Here, we experimentally study spontaneous symmetry breaking with two controllable asymmetries. We remarkably find that features typical of spontaneous symmetry breaking, while destroyed by one asymmetry, can be restored by introducing a second asymmetry. In essence, asymmetries are found to balance each other. Our study illustrates aspects of the universal unfolding of the pitchfork bifurcation, and provides new insights into a key fundamental process. It also has practical implications, showing that asymmetry can be exploited as an additional degree of freedom. In particular, it would enable sensors based on symmetry breaking or exceptional points to reach divergent sensitivity even in presence of imperfections. Our experimental implementation built around an optical fiber ring additionally constitutes the first observation of the polarization symmetry breaking of passive driven nonlinear resonators., Comment: 11 pages, 8 figures

Using a passive, coherently driven nonlinear optical fiber ring resonator, we report the experimental realization of dissipative polarization domain walls. The domain walls arise through a symmetry breaking bifurcation and consist of temporally localized structures where the amplitudes of the two polarization modes of the resonator interchange, segregating domains of orthogonal polarization states. We show that dissipative polarization domain walls can persist in the resonator without changing shape. We also demonstrate on-demand excitation, as well as pinning of domain walls at specific positions for arbitrary long times. Our results could prove useful for the analog simulation of ubiquitous domain-wall related phenomena, and pave the way to an all-optical buffer adapted to the transmission of topological bits.

We report on the experimental observation of internally pumped parametric oscillation in a high-$\!Q$Q lithium niobate microresonator under conditions of natural phase matching. Specifically, launching near-infrared pump light around 1060 nm into a $ z $z-cut congruent lithium niobate microresonator, we observe the generation of optical sidebands around the input pump under conditions where second-harmonic generation is close to natural phase matching. We find that a wide range of different sideband frequency shifts can be generated by varying the experimental parameters. Under particular conditions, we observe the cascaded generation of several sidebands around the pump-the first steps of optical frequency comb generation via cavity-enhanced second-harmonic generation.

We report numerical and experimental observations of spontaneous symmetry breaking of Kerr cavity solitons. We show that cavity solitons with mirror polarization states can co-exist and be individually addressed in a symmetric fiber ring resonator.

We report novel breathing dynamics of polarized symmetry-broken temporal cavity solitons in passive driven nonlinear resonators. We demonstrate experimentally the coexistence and also the possible spontaneous switching of two orthogonally-polarized breathers.

We report novel types of polarized symmetry-broken temporal cavity solitons in passive driven nonlinear resonators. We demonstrate experimentally individual addressing of these solitons, and simultaneous co-existence of cavity solitons with mirror polarization states. © 2020 The Author(s)

We report the observation of bright cavity solitons in Kerr resonators driven in the normal dispersion regime. The solitons are enabled by third-order dispersion, and could permit novel sources of ultrashort pulses or frequency combs.

We report on the experimental and numerical observation of polarization modulation instability (PMI) in a nonlinear fiber Kerr resonator. This phenomenon is phased-matched through the relative phase detuning between the intracavity fields associated with the two principal polarization modes of the cavity. Our experimental investigation is based on a 12 m long fiber ring resonator in which a polarization controller is inserted to finely control the level of intracavity birefringence. Depending on the amount of birefringence, the temporal patterns generated via PMI are found to be either stationary or to exhibit a period-doubled dynamics. The experimental results are in good agreement with numerical simulations based on an Ikeda map for the two orthogonally polarized modes. This Letter provides new insights into the control of modulation instability in multimode Kerr resonators., SCOPUS: ar.j, info:eu-repo/semantics/published

We report on the experimental observation of internally-pumped optical parametric oscillation and initial stages of quadratic optical frequency comb generation in a lithium niobate microresonator driven with a continuous wave laser around 1050 nm.

We demonstrate counter-proagating Kerr cavity solitons in a magnesium fluoride microresonator. Thermal effects are compensated using an auxiliary laser in a distinct spatial mode that is spectrally close to the pump.

International audience; The Central Neutron Detector is a scintillator barrel that was designed to detect 0.2-1 GeV neutrons at lab polar angles from 40 ∘ to 120 ∘ in the CLAS12 spectrometer in Hall B at Jefferson Laboratory. The design is based on three radial layers of paddles read out at the upstream end of the barrel by photomultipliers tubes. Neighboring paddles in each layer are coupled together at the downstream end of the barrel by “U-turn” light guides. The components of this detector are presented and the performance of the detector with the first beam data taken by CLAS12 is reported.

We report on a novel kind of bright polarization structure, called faticon, occurring in normally dispersive isotropic Kerr resonators. We show that these structures can be addressed individually and exploited as bit-entities for optical buffering.

We report on the experimental observation of internally-pumped optical parametric oscillation and initial stages of quadratic optical frequency comb generation in a lithium niobate microresonator under conditions of naturally phase-matched second-harmonic generation. © 2020 The Author(s)

We demonstrate widely tunable parametric oscillation in a magnesium-fluoride optical microresonator. The observed tuning range spans from 0.9 to 2.6 pm, and the presence of parametric signals out to 3.9 pm is inferred.

We experimentally study the phase matching condition of dispersive waves in a pulse-pumped normal dispersion ring resonator. The frequency shift of the dispersive waves strongly depends on the pump synchronization yielding tunable broadband combs.