Laurent Larger

Compact optoelectronic microwave oscillators using ultra-high Q whispering gallery mode disk-resonators and phase modulation

We demonstrate a compact optoelectronic oscillator based on phase modulation and ultra-high Q disk resonators. A 10.7 GHz microwave is generated, with a phase noise of -90 dBrad2/Hz at 10 kHz from the carrier, and -110 dBrad2/Hz at 100 kHz.

Optical Rogue Waves in Whispering-Gallery-Mode Resonators

Tampere University of Technology, Institute of Physics,Optics Laboratory, FIN-33101 Tampere, Finland(Dated: January 7, 2014)We report a theoretical study showing that rogue waves can emerge in whispering gallery moderesonators as the result of the chaotic interplay between Kerr nonlinearity and anomalous group-velocity dispersion. The nonlinear dynamics of the propagation of light in a whispering gallery-moderesonator is investigated using the Lugiato-Lefever equation, and we evidence a range of parameterswhere rare and extreme events associated with a non-gaussian statistics of the eld maxima areobserved.

Kerr optical frequency comb generation in strontium fluoride whispering-gallery mode resonators with billion quality factor.

We report the fabrication for the first time of a strontium fluoride (SrF(2)) whispering-gallery mode resonator with quality factor in excess of 1 billion. The millimeter-size disk-resonator is polished until the surface roughness decreases down to a root-mean square value of 1.2 nm, as measured with a vertical scanning profilometer. We also demonstrate that this ultrahigh Q resonator allows for the generation of a normal-dispersion Kerr optical frequency comb at 1550 nm.

Demonstration of a chaos generator with two time delays

We demonstrate a chaos generator involving two time delays and two nonlinear functions. Dynamic behaviors are numerically and experimentally observed. The complexity of the dynamics is discussed in terms of Lyapunov exponents and dimensions. The setup can provide a new architecture for enhancing message security in chaos encryption systems.

Estimation of the uncertainty for a phase noise optoelectronic metrology system

The configuration of the phase noise measurement system operating in the X-band (8.2?12.4?GHz) using a photonic delay line as a frequency discriminator is presented in this paper. This system does not need any excellent frequency reference and works for any frequency in this band. Oscillator frequency fluctuation is converted into phase frequency fluctuation through the delay line. The measured phase noise includes the device under test noise and the instrument background. Then the use of a cross correlation decreases the cross spectrum terms of uncommon phase noise as ?(1/m), where m is the average number. Using cross correlation on 500 averages, the noise floor of the instrument ?(f) becomes, respectively, ?150 and ?170?dBc?Hz?1 at 101 and 104?Hz from the 10?GHz carrier (?90 and ?170?dBc?Hz?1 including 2?km delay lines). We then focus on determining the uncertainty. There are two categories of uncertainty terms: type A, statistic contributions such as repeatability and experimental standard deviation; type B due to various components and temperature control. The elementary term of uncertainty for repeatability is found to be equal to 0.68?dB. Other elementary terms still have lower contributions. This leads to a global uncertainty of 1.58?dB at 2?.

Wideband chaos generation using a delayed oscillator and a two-dimensional nonlinearity induced by a quadrature phase-shift-keying electro-optic modulator

We present a new optoelectronic architecture intended for chaotic optical intensity generation. The principle relies on an electro-optic nonlinear delay dynamics, where the nonlinearity originates from an integrated four-wave optical interferometer, involving two independent electro-optic modulation inputs. Consequently, the setup involves both two-dimensional nonlinearity and dual-delay feedback dynamics, which results in enhanced chaos complexity of particular interest in chaos encryption schemes. The generated chaos observed with large feedback gains has a bandwidth ranging from 30 kHz to 13 GHz and is confirmed by numerical simulations of the proposed dynamical model and bifurcation diagram calculation.

Chaos in coherence modulation: bifurcations of an oscillator generating optical delay fluctuations

A new chaos generator is described that produces chaotic fluctuations of the optical-path difference in a coherence modulator driven electrically by a nonlinear delayed-feedback loop. Numerical simulations and experimental results are reported. A closed branch of periodic solutions bounded by a forward and a reverse Hopf bifurcation is observed for the first time, to our knowledge, for this type of nonlinear dynamical system.

Nonlinear memory capacity of parallel time-delay reservoir computers in the processing of multidimensional signals

This letter addresses the reservoir design problem in the context of delay-based reservoir computers for multidimensional input signals, parallel architectures, and real-time multitasking. First, an approximating reservoir model is presented in those frameworks that provides an explicit functional link between the reservoir architecture and its performance in the execution of a specific task. Second, the inference properties of the ridge regression estimator in the multivariate context are used to assess the impact of finite sample training on the decrease of the reservoir capacity. Finally, an empirical study is conducted that shows the adequacy of the theoretical results with the empirical performances exhibited by various reservoir architectures in the execution of several nonlinear tasks with multidimensional inputs. Our results confirm the robustness properties of the parallel reservoir architecture with respect to task misspecification and parameter choice already documented in the literature.

Theoretical and experimental study of slow-scale Hopf limit-cycles in laser-based wideband optoelectronic oscillators

Optoelectronic oscillators are the subject of extensive research because of the wide variety of associated applications, which include chaos cryptography, ultrastable microwave generation, and neuromorphic computing. The wideband optoelectronic oscillator presents a particular feature allowing for two dynamical time scales to be superimposed, namely, a slow one and a fast one. In this paper, we fully characterize the onset of the slow-scale oscillation in the wideband optoelectronic oscillator. We investigate the dynamics associated to the first Hopf bifurcation and calculate analytically both the amplitude and period of the induced limit-cycle. In particular, we show how the dynamics of the zero-delay case can be used to provide insight into the infinite-dimensional dynamics of the delayed system. Our theoretical results are in very good agreement with the experimental measurements.

Time delay extraction in chaotic cryptosystems based on optoelectronic feedback with variable delay

Chaotic wavelength transmitters based on a DBR laser submitted to optoelectronic feedback with periodic time delay are considered. We investigate the retrieval of the periodic time delay function from experimental time series. Square-wave and sinusoidal modulations are considered for the frequency clock of a delay module based on a First-In First-Out memory. It is shown that the period of the time delay can be extracted from experimental data by using the mutual information function. Different values of the nonlinearity are considered. Applying a modified filling factor method the periodic time delay function is retrieved in the sinusoidal modulation case for different periods and modulation depths.