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Semiconductor nanostructures with low dimensionality like quantum dots and quantum dashes are one of the best attractive and heuristic solutions for achieving high performance photonic devices. When one or more spatial dimensions of the nanocrystal approach the de Broglie wavelength, nanoscale size effects create a spatial quantization of carriers leading to a complete discretization of energy levels along with additional quantum phenomena like entangled-photon generation or squeezed states of light among others. This article reviews our recent findings and prospects on nanostructure based light emitters where active region is made with quantum-dot and quantum-dash nanostructures. Many applications ranging from silicon-based integrated technologies to quantum information systems rely on the utilization of such laser sources. Here, we link the material and fundamental properties with the device physics. For this purpose, spectral linewidth, polarization anisotropy, optical nonlinearities as well as microwave, dynamic and nonlinear properties are closely examined. The paper focuses on photonic devices grown on native substrates (InP and GaAs) as well as those heterogeneously and epitaxially grown on silicon substrate. This research pipelines the most exciting recent innovation developed around light emitters using nanostructures as gain media and highlights the importance of nanotechnologies on industry and society especially for shaping the future information and communication society., Quantum dot are one of the best practical examples of nanotechnologies. Owing to the discrete energy levels, quantum dot lasers output unique features like thermal stability, feedback insensitivity and spectral purity.

International audience; This study deals with the communication capabilities of two kinds of semiconductor lasers emitting in one of the atmosphere transparency windows, around 4 µm. One of these two lasers is a quantum cascade laser and the other one is an interband cascade laser. With the quantum cascade laser, a subsequent attenuation is added to the optical path in order to mimic the attenuation of free-space transmission of several kilometers. Direct electrical modulation is used to transmit the message and two-level formats, non-return-to-zero and return-to-zero, are used and compared in terms of maximum transmission data rate. The sensitivity to optical feedback is also analyzed, as well as the evolution of the error rate when reducing the optical power at the level of the detector. This work provides a novel insight into the development of future secure free-space optical communication links based on midinfrared semiconductor lasers and sheds the light on improvements required to achieve multi-Gbits/s communication with off-the-shelf components. Index Terms-Quantum cascade laser, interband cascade laser, mid-infrared photonics, free-space communication. I. INTRODUCTION T HE development of semiconductor laser technology was considerably boosted with inventing quantum cascade lasers (QCLs) in early 90s [1] and interband cascade lasers (ICLs) shortly afterwards [2]. At the early stages of QCLs, free-space optical transmissions were envisioned [3] alongside Manuscript

Mid-infrared free-space optical communication has a large potential for high speed communication due to its immunity to electromagnetic interference. However, data security against eavesdroppers is among the obstacles for private free-space communication. Here, we show that two uni-directionally coupled quantum cascade lasers operating in the chaotic regime and the synchronization between them allow for the extraction of the information that has been camouflaged in the chaotic emission. This building block represents a key tool to implement a high degree of privacy directly on the physical layer. We realize a proof-of-concept communication at a wavelength of 5.7 μm with a message encryption at a bit rate of 0.5 Mbit/s. Our demonstration of private free-space communication between a transmitter and receiver opens strategies for physical encryption and decryption of a digital message., Free-space communication in the mid-IR domain has many potential applications, but security is still challenging. Here, the authors use chaos synchronization in a QCL-based free-space link as a way to increase privacy of such transmissions.

We introduce dual-polarization probing codes based on two circularly shifted frequency sweep signals enabling perfect channel estimation. This is achieved with a probing length equal to at least twice the fiber round-trip propagation time., Conference paper (27th International Conference on Optical Fiber Sensors), 4 pages, 7 figures

We introduce a coherent-MIMO Δϕ-OTDR based sensing technique that uses digital frequency division multiplexing of probing codes in order to mitigate the coherent fading issue in Δϕ-OTDR. Orthogonal frequency division multiplexing (OFDM) is used to probe the optical channel on several electrical subcarriers, and their responses are then combined according to specific reliability criterion to enhance the overall sensing sensitivity. This allows for a decrease of the noise floor in sensing measurements on standard single mode fiber (SSMF) and the mitigation of false alarms. Coherent MIMO-OFDM enables sensing over telecom fibers with a measured sensitivity level below 21 p ε / H z along 1.3km fiber over a mechanical bandwidth of 760Hz. Enhancements in the dynamic range for detection of mechanical excitation are presented with a gain over 18dB as compared to single-carrier probing.

International audience

Brillouin optical time‐domain reflectometry (BOTDR) has the advantage of requiring access to only one end of the sensing fibre, which is an important property for some applications. The coherent detection of spontaneous Brillouin scattering allows high sensitivity of temperature/strain measurements, close to one of the well‐known Brillouin optical time‐domain analyser‐based solutions. In‐line amplification based on bidirectional erbium‐doped fibre amplification (EDFA) modules can improve sensing distance and temperature accuracy. This study demonstrates a distributed sensing over 150 km with 5‐m spatial resolution and a temperature error of less than 2°C in 10 min without requiring specific BOTDR adaptation. A record performance of 0.7°C in 60 min has been also obtained, which corresponds to the best performance obtained in reflectometer configuration at this distance.

International audience; We present a complete characterization of reflective electroabsorption modulators (EAMs) monolithically integrated with semiconductor optical amplifiers (SOAs), components that are capable of operating beyond 50 Gb/s in the C-band. The devices are based on GaInAsP multiple quantum wells on InP substrate, leveraging semi-insulating buried heterostructure waveguide definition and butt-joint integration technologies. Different device configurations, based on 80-μm and 150-μm long EAMs, are fabricated and characterized in both static and dynamic modes. The frequency response of the 80-μm long EAM is still flat at 26.5 GHz (setup upper limit) whereas the 150-μm long EAM exhibits a 3-dB cutoff bandwidth of 23 GHz. A zero-chirp is achieved for EAM reverse bias voltages between −1.2 V and −1.5 V depending on the wavelength. Under large-signal modulation, the frequency chirp induced by the shorter EAM is almost half that of the longer EAM, with their respective peak values being +1.5/−2 GHz and +3.2/−3.7 GHz (rising/falling edges) at 1545 nm (−1.3 V bias, 2.6 V voltage swing). We obtained high dynamic extinction ratios of ~14.5 dB and ~8 dB from the longer and the shorter EAMs, respectively, when they are operated at 25 Gb/s using non-return-to-zero coding. Finally, we achieved 12 km and 16 km colorless transmissions in the C-band (between 1530 nm and 1545 nm) over a standard single-mode fiber without equalization using the 150-μm and the 80-μm EAMs, respectively, with 4.5 dB and 2.5 dB dispersion penalties at a bit error rate of 10E−3.

We report on the first experimental chaos synchronization in mid-infrared quantum cascade lasers and subsequently perform private free-space transmission at a bit-rate of 0.5 Mbits/s. The quality of the privacy is assessed with eye diagrams, both at the legitimate receiver side and illegitimate receiver side.

International audience

Silicon-based epitaxial quantum dot (QD) lasers with strong tolerance for back-reflections have paved the way for developing isolator-free photonics integrated circuits (PICs). This remarkable feature is attributed to the peculiar benefits of QDs, including a large material gain, a strong damping, and a small linewidth enhancement factor [1] . The laser performance can also be optimized by applying p-modulation doping in the active region [1] . In a previous study, the sensitivity of epitaxial QD lasers on silicon subject to short- and long-delay optical feedback were performed [2] . On the top of that, a further investigation of the feedback dynamics on the intra- and inter-chip scale is of significant importance for photonic integration applications.

International audience; We demonstrate the performance of a novel multi-carrier MIMO fiber sensing interrogator based on OFDM approach. Over an installed telecom fiber cable, coherent fading is mitigated by means of a purely digital subcarrier combiner.

International audience; We experimentally display temporal chaotic waveforms in the mid-infrared domain with two different types of semiconductor lasers. The generated high-dimensional non-linear dynamics are of prime interest for private communications and physical random number generation.

Quantum cascade lasers (QCLs) are optical sources exploiting radiative intersubband transitions within the conduction band of semiconductor heterostructures.1 Mid-infrared QCLs have been thoroughly considered for applications such as spectroscopy,2 free-space communications3 and countermeasure systems.4 Under self-optical feedback, QCLs have been proven to operate in several non-linear dynamic regimes,5 including low-frequency fluctuations and deterministic chaos, which are suitable for private communications taking advantage of both chaos masking and background stealth. However, the previous experiments focused on distributed feedback (DFB) quantum cascade lasers emitting at 5.7 µm, which is not an optimized wavelength for free-space applications. Indeed the atmosphere is characterized by two transparency windows between 3-4 µm and 8-12 µm, which are called bandpass L and bandpass N, respectively.6 Furthermore, the 5.7 µm lasers were studied at the chip level, which means that end users must own the dedicated mounts, connectors and mid-infrared optics in order to take advantage of these quantum cascade sources. This work extends our knowledge by exploring the non- linear dynamics of a packaged Fabry-Perot (FP) QCL emitting at 4 µm. The advantage of the FP configuration is an increased output-power compared to DFB sources, though the FP configuration is not well-known yet.7 Moreover, this laser comes in a handy environment with embedded focusing optics and high-heat load (HHL) packaging for plug-and-play operation. Consequently, the current findings pave the way for off-the-shelf private s at mid-infrared wavelength where high-power and compact turnkey systems are required.

The sensitivity of a hybrid distributed feedback semiconductor (DFB) laser heterogeneously integrated onto silicon (Si) is extensively characterized in the presence of external optical feedback at different bias and temperature conditions. The unique modal engineering approach of the device allows the light generated in the III-V material to be stored in the low-loss Si region to significantly enhance the quality (Q) factor of the cavity resonator. This design leads to an increased temperature tolerance of the laser without impacting the transmission efficiency even under the most severe feedback conditions. At a temperature of T = 35◦C, the laser continuous to unveil optimal performance and exhibits feedback insensitivity when externally modulated at 10 Gbps transmission over a 10 km fiber coil. The study presented here demonstrates the ability of a high-Q laser to achieve floor-free transmission at different operating conditions with a power penalty degradation no greater than 1.5 dB. The prolonged transition to the coherence collapse regime at a much higher reflection level evidenced by this device when compared to its III-V counterparts in addition to its ability to withstand perturbations associated with temperature variations and unintentional back-reflections delivers a step forward towards isolator-free applications. This work suggest that this type of semiconductor lasers can serve as a promising solution for the development of compact and reliable photonic integrated circuits (PICs).

This work reports on an investigation of the dynamics of $1.3\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\text{m}$ epitaxial quantum dot (QD) lasers on silicon subject to delayed optical feedback. Operating the device under different feedback conditions, we experimentally identify various dynamical states of periodic oscillations. In the long-cavity feedback regime, the device remains chaos-free up to $\ensuremath{\approx}70% (\ensuremath{-}1.55\phantom{\rule{0.16em}{0ex}}\mathrm{dB})$ feedback strength. This remarkable result is in agreement with prior studies and is attributed to the particular design and properties of the QD-based active region. Shortening the external cavity length to the short-cavity regime being on the scale of photonics integrated circuits (PICs), the onset of periodic oscillations only takes place under extremely high feedback strength, which is much higher than those in PICs. The devices studied exhibit strong resistance to chip-scale back reflections in absence of any unstable oscillation. Our results also demonstrate that p doping is an efficient technique to further improve the feedback tolerance. These results point out the potential of QD lasers as an on-chip light source not requiring an optical isolator and gives insights for developing ultrastable silicon transmitters for PIC applications.

Differential phase optical time-domain reflectometry is subject to Rayleigh fading, which locally impedes proper phase extraction. We introduce in this Letter a reliability metric derived from the measured Jones matrix estimates of the fiber sensor to discriminate between true perturbations and false alarms caused by Rayleigh backscatter fading points. The proposed soft-decision metric is also of interest for further post-processing stages exploiting artificial intelligence based classifiers.

International audience; We experimentally present a 10-Gb/s Fiber Wireless IFoF/V-band uplink of four625Mbaud 16QAM signals with a linear, high-power monolithically integrated reflective electroabsorptionmodulator with semiconductor optical amplifier for 5G mmWave fronthaul networks.

This work reports on a high-efficiency InAs/GaAs distributed feedback quantum dot laser. The large optical wavelength detuning at room temperature between the lasing peak and the gain peak causes the static, dynamic, and nonlinear intrinsic properties to all improve with temperature, including the lasing efficiency, the modulation dynamics, the linewidth enhancement factor, and consequently the reflection insensitivity. Results reported show an optimum operating temperature at 75°C, highlighting the potential of the large optical mismatch assisted single-frequency laser for the development of uncooled and isolator-free high-speed photonic integrated circuits.

A unique feature of quantum cascade lasers relies on the ultrafast carrier relaxation lifetime that occurs on a picosecond time scale. Furthermore, the very sharp electronic transitions among the conduction-band states (subbands) lead to specific selection rules, which in theory exclude the TE-polarized light emission. Under cross-polarization reinjection, we stimulate the polarization switching dynamics in such an intersubband device. The mid-infrared modulation signal is phase-shifted between the TM mode and the TE mode, with a typical microsecond time scale different from pure time-delay dynamics. We also prove that both the frequency and the duty cycle of the modulated pattern can be slightly tuned by varying the characteristics of the reinjected light. These results reveal the possibility of favoring the TE polarization in a quantum cascade laser and generating a square-wave modulation with cross-polarization reinjection.

International audience; We experimentally realize a free-space transmission over one meter with roomtemperature quantum cascade lasers and interband cascade lasers. With direct electrical modulation and raw analysis, the data-rate of the real-time transmission outperforms similar reported schemes.

International audience; We demonstrate experimentally that mid-infrared quantum cascade lasers (QCLs) operating under external optical feedback exhibit extreme pulses. These events can be triggered by adding small amplitude periodic modulation, with the highest success rate for the case of a pulse-up excitation. These findings broaden the potential applications for QCLs, which have already been proven to be a semiconductor laser of interest for spectroscopic applications and countermeasure systems. The ability to trigger extreme events paves the way for optical neuron-like systems where information propagates as a result of high intensity bursts.

We demonstrate an all-optical square modulation in a room-temperature quantum cascade laser with cross-polarization reinjection. The duty cycle of the pattern is controlled by varying the components of the polarization, paving the way for integrated photonic memories and direct modulation of light at mid-infrared wavelength.

This work investigates the dynamics of two-state quantum dot lasers through semi-analytically solving a set of rate equations. Simulations reveal that the occurrence of excited state lasing reduces the damping factor and relaxation oscillation frequency of the laser while increases the linewidth enhancement factor associated to the ground state transition. These results are in good agreement with the experimental observation showing that the quantum dot laser becomes more sensitive to external optical feedback at excited state lasing threshold. This work brings novel insights in the understanding of quantum dot laser physics that are useful for designing feedback resistant lasers in photonic integrated technologies.

This work experimentally investigates the impact of p-doping on the relative intensity noise (RIN) properties and subsequently on the modulation properties of semiconductor quantum dot (QD) lasers epitaxially grown on silicon. Owing to the low threading dislocation density and the p-modulation doped GaAs barrier layer in the active region, the RIN level is found very stable with temperature with a minimum value of − 150 d B / H z . The dynamical features extracted from the RIN spectra show that p-doping between zero and 20 holes/dot strongly modifies the modulation properties and gain nonlinearities through increased internal losses in the active region and thereby hinders the maximum achievable bandwidth. Overall, this Letter is important for designing future high-speed and low-noise QD devices integrated in future photonic integrated circuits.

This work reports on an investigation of the optical feedback in an InAs/InGaAs passively mode-locked quantum dot (QD) laser epitaxially grown on silicon. Under the stably-resonant optical feedback condition, experiments demonstrate that the radio-frequency linewidth is narrowed whatever the bias voltage applied on the saturable absorber (SA) is; on the other hand, the effective linewidth enhancement factor of the device increases with the reverse bias voltage on the SA, hence it is observed that such an increase influences the mode-locking dynamic and the stability of device under optical feedback. This work gives insights for stabilizing epitaxial QD mode-locked lasers on silicon which is meaningful for their applications in future large-scale silicon electronic and photonic applications requiring low power consumption as well as for high-speed photonic analog-to-digital conversion, intrachip/interchip optical clock distribution and recovery.

We explore the alternatives for interrogating a fiber sensor from the polarization point of view, and demonstrate a better accuracy with dual polarization probing for coherent phi-OTDR compared with single polarization probing., Comment: Conference paper (27th International Conference on Optical Fiber Sensors, 2020), 4 pages, 6 figures

This paper deals with polarization-multiplexed optical transmissions. It addresses the challenge of designing optimal yet practical modulation codes for the 2×2 MIMO fiber channel. This specific use case diverges from classical MIMO models encountered, e.g., in the wireless literature as, here, non-ergodicity and low-complexity are key. While rather simple from a fundamental viewpoint, the proposed modulation schemes appears to be optimal and geometrically pleasing as the second minimum distance turns out to be the object of interest and the associated vectors encode the basis of a regular tetrahedron in the affine space. From an operational viewpoint, these new schemes for single channel use form polarization codes that achieve unit dB gains while exhibiting low implementation complexity.

Nowadays, long distance optical fibre transmission systems use polarization diversity multiplexed signals to enhance transmission performance. Distributed acoustic sensors (DAS) use the same propagation medium ie. single mode optical fibre, and aims at comparable targets such as covering the highest distance with the best signal quality. In the case of sensors, a noiseless transmission enables to monitor a large quantity of mechanical events along the fibre. This paper aims at extending the perspectives of DAS systems with regard to technology breakthroughs introduced in long haul transmission systems over the last decade. We recently developed a sensor interrogation method based on coherent phase-sensitive optical time domain reflectometry ($\phi$-OTDR), with dual polarization multiplexing at the transmitter and polarization diversity at the receiver. We name this technique Coherent-MIMO sensing. A study is performed from a dual-polarization numerical model to compare several sensor interrogation techniques, including Coherent-MIMO. We demonstrate that dual-polarization probing of a fibre sensor makes it insensitive to polarization effects, decreases the risks of false alarms and thus strongly enhances its sensitivity. The simulations results are validated with an experiment, and finally quantitative data are given on the performance increase enabled by Coherent-MIMO sensing., Comment: 14 pages, 20 figures and subfigures. Submitted to Optics Express (after 1st revision)

International audience; We experimentally build a basic optical neuron by taking advantage of excitability in a semiconductor laser under optical feedback, rather than conventional injection schemes. This optical neuron operates faster than its biological and electronical counterparts.

International audience; This work reports on the optical feedback dynamics of InAs/GaAs QD lasers epitaxially grown on silicon operating in both the short and long delay regimes. Both undoped and p-doped QD lasers are considered. Whatever the external cavity length, no chaotic oscillations are observed on both samples as a result of the small α-factor observed in the silicon QD lasers. Despite that, experiments conducted in the short-cavity region raise period-one oscillation for the undoped QD laser. In addition, the transition from the short to long delay regimes can be finely covered by varying the external cavity length from 5 cm to 50 cm, and the boundaries associated to the appearance of the periodic oscillation are identified. In the short-cavity region, boundaries show some residual undulations resulting from interferences between internal and external cavity modes; whereas in the long-delay regime, the feedback ratio delimiting the boundaries keeps decreasing, until it progressively becomes rather independent of the external cavity length. Overall, our results showed that the p-doped device clearly exhibits a much higher tolerance to the different external feedback conditions than the undoped one, seeing that its periodic oscillation boundaries are barely impossible to retrieve at the maximum feedback strength of-7 dB. These results show for the first time the p-modulation doping effect on the enhancement of feedback insensitivity in both short-and long-delay configurations, which is of paramount importance for the development of ultra-stable silicon transmitters for photonic technologies.

we present a 50 Gb/s O-band reflective electroabsorption modulator operating in both non-return-to-zero (NRZ) and PAM-4 modulation formats without equalization. We obtained >9 dB NRZ dynamic extinction ratio for a peak-to-peak voltage of 2.4 V.

Direct epitaxial growth of III-V lasers on silicon provides the most economically favorable means of photonic integration but has traditionally been hindered by poor material quality. Relative to commercialized heterogeneous integration schemes, epitaxial growth reduces complexity and increases scalability by moving to 300 mm wafer diameters. The challenges associated with the crystalline mismatch between III-Vs and Si can be overcome through optimized buffer layers including thermal cyclic annealing and metamorphic layers, which we have utilized to achieve dislocation densities 10,000,000 h). At 60°C, lasers with extrapolated time-to-failure >50,000 h have been demonstrated for >4,000 h of continuous aging. Lasers have also been investigated for their performance under optical feedback and showed no evidence of coherence collapse at back-reflection levels of 100% (minus 10% tap for measurement) due to the ultralow linewidth enhancement factor (αH < 0.2) and high damping of the optimized quantum dot active region.

20dB gain in C-band with only 5.3W of pump is achieved with an all-fiberized 12-core Er/Yb doped fiber amplifier. This result is a first step towards SDM transmission including power efficient amplifiers and ROADM.

We report on mid-IR supercontinuum generation in an all-silica nanosecond pulsed fiber laser. The laser topology is a master oscillator power amplifier which consists of a two stage Thulium-doped fiber amplifier seeded with a directly modulated semiconductor laser at 1952 nm. The supercontinuum performance is investigated for repetition rate frequencies between 35 kHz and 100 kHz and pulse widths between 6 ns and 21 ns. Supercontinuum average output powers greater than 1.5 W and spectra ranging from 1.95 µm to 2.65 µm are demonstrated.

This work investigates the performance of 1.3-μm quantum dot lasers epitaxially grown on silicon under optical feedback sensitivity with different temperature and doping profiles. Experiments show that these quantum dot lasers exhibit a very high degree of resistance to both incoherent and coherent optical feedbacks. 10 Gbps penalty-free transmissions are also unveiled under external modulation and at different temperatures. The paper draws attention on quantum dot lasers with p-doping that exhibit a better thermal resistance, a lower linewidth enhancement factor, a higher critical feedback level, and a better spectral stability with less intensity noise. Together, these properties make epitaxial quantum dot lasers with p-doping more promising for isolator-free and Peltier-free applications, which are meaningful for future high-speed photonic integrated circuits.

We show here the efficiency of neural network to assist the linear DSP for mitigating 200G DP-16QAM transmission system impairments. We measure up to 1-dB Q-factor improvement in our Nx100-km G.652 fiber link experiment.

International audience; Quantum cascade lasers (QCLs) under optical feedback can output several non-linear dynamics whose properties depend on the reinjected light polarization. We demonstrate all-optical modulation, thresholding and excitability in QCLs, to experimentally build basic optical neurons.

This paper theoretically investigates the optical noise characteristics of the simultaneous ground-state (GS) and excited-state (ES) lasing quantum dot lasers. The optical noise dynamics of both states are analysed through coupling the Langevin noise sources into a set of coupled rate equations. It is pointed out that the ES emission significantly changes the evolution scenario of the relative intensity noise, the frequency noise (spectral linewidth), and the linewidth broadening factor of the GS emission, as a function of the bias current. In the vicinity of the ES lasing threshold, the relative intensity noise and the frequency noise of the GS emission is lower than those of ES emission. However, the linewidth broadening factor of the GS emission is larger than the latter.

We report on two recent high performance semiconductor lasers made with the silicon photonic platform. Both structures display a quasi complete reflection insensitivity, resulting in a key attribute for the development of isolator-free integrated technologies.

We report on a passively mode-locked oscillator based on an erbium-doped dual concentric core fiber combining high normal dispersion and large mode area. This large normal dispersion laser generates long pulses with 30 ps duration and 0.17 nm spectral width at 1530 nm wavelength. The source delivers an average power of 64 mW at a repetition rate of 16 MHz, corresponding to 4 nJ energy. This concept opens up new degrees of freedom in the design of mode-locked fiber lasers.

The Cloud-Enhanced Open Software Defined Mobile Wireless Testbed for City-Scale Deployment (COSMOS) platform is a programmable city-scale shared multi-user advanced wireless testbed that is being deployed in West Harlem of New York City [1]. To keep pace with the significantly increased wireless link bandwidth and to effectively integrate the emerging C-RANs, COSMOS is designed to incorporate a fast programmable core network for providing connections across different computing layers. A key feature of COSMOS is its dark fiber based optical x-haul network that enables both highly flexible, user defined network topologies and experimentation directly in the optical physical layer. The optical architecture of COSMOS was presented in [2]. In this abstract, we present the tools and services designed to configure and monitor the performance of optical paths and topologies of the COSMOS testbed. In particular, we present the SDN framework that allows testbed users to implement experiments with application-driven control of optical and data networking functionalities.

This work investigates the effect of the polarization anisotropy on the linewidth enhancement factor and the reflection sensitivity of InAs/InP quantum dash semiconductor lasers. The results show that the small linewidth enhancement factor and high stability against external optical feedback are obtained for nanostructures oriented perpendicular to the cavity axis as opposed to those oriented parallel to the cavity axis. Effective simulations on the critical feedback level of these two lasers are also in agreement with experimental results. Such anisotropy is attributed to the polarization dependence of the transition matrix element in these quantum nanostructures.

Advance in optical transmission towards higher bit rate and denser spectral efficiency is challenged by nonlinear effects. The existing digital signal processing techniques to compensate nonlinear fiber transmission impairments suffer from heavy computations and require the knowledge of a large number of system parameters, which is impractical in field environment. Neural networks are among the investigated solutions in literature to cope with the complexity of those models. Taking advantage of the huge amount of data available in optical transport networks, WDM systems represent a fertile field to apply neural networks.This paper is a non-exhaustive survey on neural network applications for nonlinear impairments mitigation in optical fiber transmission systems. We distinguish two approaches. The first one is dependent of the NonLinear Schrodinger Equation (NLSE) while the second one is based on machine learning techniques. These two approaches achieve similar performance compared to the well-known nonlinear mitigation methods with reduced computational complexity.

Integrating transponders enabling higher capacity and implementing the latest transmission technologies is a frequent process in the life-cycle of operational optical network in order to respond to the continuous traffic growth. Therefore, moving towards interoperable and open transponders is a priority target of operators in order to replace the mono-vendor supplying model by a more competitive multi-vendor model and, in consequence, reduce the infrastructure cost. This process, commonly called "alien wavelength" support, requires that the network management software be able not only to control the multi-vendor transponders, but also estimate lightpath performance. Standard sets of parameters and protocol extensions enable the use of vendor-agnostic open-source tools, avoiding vendor lock-in. This paper describes different interoperable solutions and discusses their efficiency based on a comprehensive set of criteria related to the complexity of deployment, applicability to legacy equipment, cost and level of openness and interoperability.

International audience; This work experimentally investigates the relative intensity noise (RIN) of semiconductor quantum dot (QD) lasers epitaxially grown on silicon. Owing to the low threading dislocations density and the p-modulation doped GaAs barrier layer in the active region, a RIN level as low as-150 dB/Hz at 9 GHz is demonstrated. The results show that the p-doping decreases the high-frequency RIN and the damping factor. In the latter, a damping factor up to 30 GHz at three times the threshold is extracted from the RIN spectrum along with a K-factor of 1.7 ns. These results pave the way for high speed and low noise QD devices for future integrated photonics technologies.

International audience; We report on possible 75% lower energy consumption for packet transport in data center networks replacing Electronic with Hybrid Optical Packet Switching (optical switches with a shared electronic buffer) combined with enhanced Transmission Control Protocol.

We present a kW level pulsed laser based on a master oscillator power amplifier (MOPA) configuration. The directly modulated single frequency laser at 1952 nm was pulsed in the nanosecond regime with a repetition rate frequency from 10 kHz to 2 MHz. The MOPA topology was based on a two stage amplifier using single clad Thulium-doped fiber: it consisted of a pre-amplifier stage followed by a booster stage. We investigated the performance of this pulsed laser for two different TDFs with different saturating energies in the booster stage. The direct modulation allowed us to demonstrate more than 1 kW of output peak power over pulse repetition frequencies from 10 kHz to 500 kHz. For a pulse duration of 21 ns, we measured output energy of 13 μJ and 29 μJ for booster fiber saturating energies of 15 μJ and 30 μJ, respectively.

SPIE OPTO, 2019, San Francisco, California, United States; International audience; Quantum cascade lasers (QCLs) are optical sources exploiting radiative intersubband transitions within theconduction band of semiconductor heterostructures. The opportunity given by the broad span of wavelengthsthat QCLs can achieve, from mid-infrared to terahertz, leads to a wide number of applications such as absorptionspectroscopy, optical countermeasures and free-space communications requiring stable single-mode operationwith a narrow linewidth and high output power. One of the parameters of paramount importance for studyingthe high-speed and nonlinear dynamical properties of QCLs is the linewidth enhancement factor (LEF). TheLEF quanties the coupling between the gain and the refractive index of the QCL or, in a similar manner, thecoupling between the phase and the amplitude of the electrical field. Prior work focused on experimental studiesof the LEF for pump currents above threshold but without exceeding 12% of the threshold current at 283Kand 56% of the threshold current at 82K. In this work, we use the Hakki-Paoli method6 to retrieve the LEF forcurrent biases below threshold. We complement our ndings using the self-mixing interferometry technique toobtain LEFs for current biases up to more than 100% of the threshold current. These insets are meaningful tounderstand the behavior of QCLs, which exhibit a strongly temperature sensitive chaotic bubble when subjectto external optical feedback.

Part 2: Poster Papers; International audience; Optical Packet Switching is a prominent technology proposing not only a reduction of the energy consumption by the elimination of numerous optical-electrical-optical conversions in electronic switches, but also a decrease of network latencies due to the cut-through nature of packet transmission. However, it is adversely affected by packet contention, preventing its deployment. Solutions have been proposed to tackle the problem: addition of shared electronic buffers to optical switches (then called hybrid opto-electronic switches), customization of TCP protocols, and use of different service classes of packets with distinct switching criteria.In the context of data center networks we investigate a combination of said solutions and show that the hybrid switch, compared to the optical switch, boosts the performance of the data center network. Furthermore, we show that introducing a “Reliable” service class improves performance for this class not only in the case of the hybrid switch, but also brings the optical switch to performance levels comparable to that of the hybrid switch, all the while keeping other classes’ performance on the same level.