Kamel Merghem

Telecom SudParis Institut Polytechnique de Paris · EPh

We demonstrate externally modulated widely tunable lasers co-integrated with semiconductor optical amplifiers (SOAs) heterogeneously integrated on silicon. The widely tunable laser enables continuous single-mode operation over a tuning range of approximately 40 nm, with a side-mode suppression ratio (SMSR) of at least 50 dB and an average waveguide...

We demonstrate self-pulsing in a single-section III-V-on-Silicon DFB laser, with a tunable pulsation frequency from 7 GHz to 2.38 GHz. Further investigation into the self-pulsation mechanism under controlled optical injection.

The study shows that, in waveguide (WG) configuration, the coupling of a 2D plasmonic metamaterial grating (MMG) having a conventional Bragg period along the guide but a distinct period along the transverse axis can lead to Electromagnetically‐Induced‐Transparency (EIT) behavior. This epitomizes that metamaterials, as functional photonic building b...

We experimentally demonstrate quantum-dash laser performance improvement by injecting optical noise and coherent feedback. The results show the amplification of the side mode lines while preserving the mode-locking and drastically reducing the individual comb linewidth.

We experimentally identified different optical coherent feedback sub-regimes of a quantum-dash mode-locked laser as a function of the feedback strength. The results render the laser a versatile source.

Nous avons étudié expérimentalement les performances de lasers à verrouillage de modes à base de bâtonnets quantiques soumis à différents régimes de rétroaction optique cohérente et incohérente. Les effets de la rétroaction optique pour des régimes spécifiques permettent de faire évoluer les caractéristiques de cette source et réaliser un peigne de...

Hopfield networks are iterative procedures able to solve combinatorial optimization problems. New studies regarding algorithm-architecture adequacy are fostered by the re-emergence of hardware implementations of such methods in the form of Ising machines. In this work, we propose an optoelectronic architecture suitable for fast processing and low e...

We propose an optoelectronic Coherent Ising Machine implemented using off-the-shelf optical telecommunications devices for image denoising for the first time. Our hardware implementation yields clean images with a pixel error rate of 3%.

We demonstrate a heterogeneously integrated III-V-on-SOI distributed feedback laser with a low grating strength (κ < 40 cm⁻¹) and a narrow linewidth of Δν = 118 kHz. The laser operates single mode with a side-mode suppression ratio over 45 dB, provides a single-sided waveguide-coupled output power of 22 mW (13.4 dBm) and has a wall-plug efficiency...

We investigate the properties of a semiconductor laser with arbitrary levels of external optical feedback, by means of an iterative travelling-wave (ITW) model. Bifurcation diagrams and the corresponding Lyapunov exponent are used to describe the behavior of the feedback laser as the external feedback reflectivity increases from 0 to 1. Similaritie...

Detection of Alzheimer's disease from handwritten features using a photonic reservoir computer.

Artificial Neural Networks (ANNs) have amassed unprecedented success in information processing ranging from image recognition to time series prediction. The success can largely be attributed to the availability of large datasets for training and the increased complexity of the models. Unfortunately, for some applications only a limited amount of sa...

We investigate the properties of a semiconductor laser with arbitrary levels of external optical feedback, by means of an iterative travelling-wave (ITW) model. Bifurcation diagrams and the corresponding Lyapunov exponent are used to describe the behavior of the feedback laser as the external feedback reflectivity increases from 0 to 1. Similaritie...

We investigate theoretically the stability properties of semiconductor lasers with optoelectronic feedback created by external optical feedback, by means of asymptotic methods. The impact of this dual-feedback configuration on the first Hopf bifurcation is discussed.

We describe the bifurcation route of a semiconductor laser with external optical feedback by use of Lyapunov exponent/fractal. The Feigenbaum «r∞-value» is proposed as the critical value for identifying the limit of the Lang-Kobayashi model.

Chip-scale frequency comb generators lend themselves as multi-wavelength light sources in highly scalable wavelength-division multiplexing (WDM) transmitters and coherent receivers. Among different options, quantum-dash (QD) mode-locked laser diodes (MLLD) stand out due to their compactness and simple operation along with the ability to provide a f...

We investigate the properties of a semiconductor laser with arbitrary levels of external optical feedback, by means of an iterative travelling-wave (ITW) model. Bifurcation diagrams and the corresponding Lyapunov exponent are used to describe the behavior of the feedback laser as the external feedback reflectivity increases from 0 to 1. Similaritie...

Single section quantum dash (QDash) mode locked lasers (MLL) can provide a flat and broadband optical frequency comb with low energy consumption, operational simplicity and large-scale low-cost production possibilities. MLL longitudinal modes can be employed as single carriers with a regular spectral spacing in a dense wavelength division multiplex...

Quantum-dash (QD) mode-locked laser diodes (MLLD) lend themselves as chip-scale frequency comb generators for highly scalable wavelength-division multiplexing (WDM) links in future data-center, campus-area, or metropolitan networks. Driven by a simple DC current, the devices generate flat broadband frequency combs, containing tens of equidistant op...

Chip-scale frequency comb generators have the potential to become key building blocks of compact wavelength-division multiplexing (WDM) transceivers in future metropolitan or campus-area networks. Among the various comb generator concepts, quantum-dash (QD) mode-locked laser diodes (MLLD) stand out as a particularly promising option, combining smal...

Quantum-dash (QD) mode-locked laser diodes (MLLD) lend themselves as chip-scale frequency comb generators for highly scalable wavelength-division multiplexing (WDM) links in future data-center, campus-area, or metropolitan networks. Driven by a simple DC current, the devices generate flat broadband frequency combs, containing tens of equidistant op...

Chip-scale frequency comb generators have the potential to become key building blocks of compact wavelength-division multiplexing (WDM) transceivers in future metropolitan or campus-area networks. Among the various comb generator concepts, quantum-dash (QD) mode-locked laser diodes (MLLD) stand out as a particularly promising option, combining smal...

We report on a mode locked semiconductor laser for high-power pulse generation in the 810 nm waveband. This is based on a novel GaAsP/GaInP single quantum-well structure, with Aluminum-free active region. Average output powers higher than 40 mW are reported in narrow ridge two-section devices. A 1.65 mm-long laser with 70 μm saturable absorber yiel...

We propose a very fast heterodyne technique to recover the amplitude and phase of short optical pulses generated e.g. by a mode-locked laser. A linearly swept frequency source is used to scan the entire optical spectrum of the mode-locked laser in a single continuous sweep. The beat signal is recorded on a fast oscilloscope and then digitally proce...

Device characterization of Quantum-Dash semiconductor mode-locked laser using a continuous tuning swept source is presented. This technique is linear, simple and does not require any prior information about the signal under test.

GaN is a durable, radiation hard and wide-bandgap semiconductor material, making it ideal for usage with betavoltaic batteries. This paper describes the design, fabrication and experimental testing of 1 cm² GaN-based betavoltaic batteries (that achieve an output power of 2.23 nW) along with a full model that accurately simulates the device performa...

The electrical response of gallium nitride (GaN), produced through metal-organic chemical vapor deposition in a p-i-n structure was investigated through temperature-dependent current-voltage (I-V) and admittance measurement. The I-V curves showed double diode behavior together with several distinct regions in which trap-assisted tunnelling current...

We demonstrate systematic resonance fluorescence recovery with near-unity emission efficiency in single quantum dots embedded in a charge-tunable device in a wave-guiding geometry. The quantum dot charge state is controlled by a gate voltage, through carrier tunneling from a close-lying Fermi sea, stabilizing the resonantly photocreated electron-ho...

We map the phase-space trajectories of an external-cavity semiconductor laser using phase portraits. This is both a visualization tool as well as a thoroughly quantitative approach enabling unprecedented insight into the dynamical regimes, from continuous-wave through coherence collapse as feedback is increased. Namely, the phase portraits in the i...

We present our systematic work on in situ generation of In nanoparticles (NPs) from the reduction of ITO thin films by hydrogen (H2) plasma exposure. In contrast with NP deposition from vapor phase (i.e. evaporation), ITO surface can be considered as a solid reservoir of In atoms thanks to the H2 plasma reduction. On one hand, below the In melting...

A fiber coupled terahertz time-domain spectroscopy (THz TDS) system which is driven by a pulsed monolithic semiconductor laser is presented. A bandwidth of over 0.6 THz with a signal to noise ratio (SNR) of 45 dB has been achieved at a wavelength of 1550 nm. This concept could pave the way towards ultra-compact and low-cost THz TDS systems.

The (de)modulation of broadband orthogonal subchannels relying on all-analogue signal processing potentially achieves high-capacity orthogonal subcarrier multiplexing (OSCM) electro-optical transceivers with low power consumption and latency. Overall transmission rates can be multiplied by employing wavelength division multiplexing (WDM) technology...

DOI:https://doi.org/10.1103/PhysRevLett.118.159901

Laser diodes with optical feedback can exhibit periodic intensity oscillations at or near the relaxation-oscillation frequency. We demonstrate optoelectronic oscillators based on external-cavity semiconductor lasers in a periodic dynamical regime tunable over the entire X-band. Moreover, unlike standard optoelectronic oscillators, we need not emplo...

Single-mode diode lasers on an InP(001) substrate have been developed using InAs/In0.53Ga0.47As quantum dash (Qdash) active regions and etched lateral Bragg gratings. The lasers have been designed to operate at wavelengths near 2 μm and exhibit a threshold current of 65 mA for a 600 μm long cavity, and a room temperature continuous wave output powe...

Quantum dash (Q-Dash) passively mode-locked lasers (PMLLs) exhibit significant low frequency relative intensity noise (RIN), due to the high mode partition noise (MPN), which prevents the implementation of multilevel amplitude modulation formats such as PAM4. The authors demonstrate low frequency RIN mitigation by employing 8B/10B and Manchester en...

We demonstrate coherent WDM transmission using a pair of quantum-dash modelocked laser-diodes - one to generate a multitude of optical carriers, and another to generate a multitude of LO tones. We transmit a line rate of 4 Tbit/s (23×45 GBd PDM-QPSK) over 75 km.

We demonstrate coherent WDM transmission using a quantum-dash mode-locked laser diode with resonant feedback. We report a line rate of 12 Tbit/s (32QAM 60×20 GBd PDM) over 75 km SMF. The spectral efficiency is 7.5 bit/s/Hz.

We consider the solid-liquid-solid (SLS) process of in-plane silicon nanowire growth from a point of view of spontaneous motion of indium (In) droplets on hydrogenated amorphous silicon (a-Si:H) coated substrates, and intermixing with the a-Si:H layer and precipitating crystalline silicon (c-Si) nanowires (NWs). Detailed SEM studies of the nanowire...

We address the production of indium nanoparticles (In NPs) from In thin films thermally evaporated on both c-Si substrates and sputtered indium tin oxide (ITO) as well as from sputtered ITO thin films, exposed to a hydrogen (H2) plasma. On the one hand, we show that evaporated In thin films grow in Volmer-Weber (VW) mode; H2 plasma reduces their su...

We experimentally investigate the corner frequency in the 1/f frequency noise of the longitudinal modes of an InAs/InP quantum-dash based single-section passive mode-locked laser. The corner frequency features a strong asymmetry across the optical frequency comb with the values ranging from 10 MHz in the low-frequency side to 180 MHz in the high-fr...

We have realized a dual-frequency VECSEL at 1.5 μm. Laser emission of two orthogonally-polarized cavity modes is obtained by inserting a birefringent crystal into the VECSEL cavity. We have examined the influence of the different intra-cavity elements on the laser emission. It is shown that optimizing the free spectral range and the bandwidth of th...

We study the time coherence of the photoluminescence radiated by spatially indirect excitons confined in a 10 $\mu$m electrostatic trap. Above a critical temperature of 1 Kelvin, we show that the photoluminescence has a homogeneous spectral width of about 500 $\mu$eV which weakly varies with the exciton density. By contrast, the spectral width redu...

We investigate the amplitude and phase noise of an optical frequency comb based on InAs/InP Quantum-dash modelocked laser. The laser demonstrates low relative intensity noise (<-125 dB/Hz) and phase noise in the passive mode-locking regime. By actively mode-locking the laser, we observe a reduction in the flicker FM noise and timing jitter, as a re...

Massive bosonic particles realise a rich variety of collective quantum phenomena where their underlying fermionic structure is hardly observed. For example, Bose-Einstein condensation of atomic gases is quantitatively understood by neglecting the atoms fermionic nature. Semiconductor excitons, i.e. Coulomb-bound electron-hole pairs, constitute a cl...

We investigate the amplitude and phase noise of an optical frequency comb based on InAs/InP Quantum-dash (Qdash) mode-locked laser (MLL). The laser demonstrates low relative intensity noise (RIN) and phase noise in the passive regime. By actively mode-locking the laser, we observe a reduction in the 1/f phase noise and timing jitter, as a result of...

This paper reports on the monitoring of long-term repetition frequency stability of InAs/InP quantum-dash based mode locked lasers using the terminal voltage fluctuations. We show unambiguous correlation between these two parameters, of particular interest for future development of frequency stabilization schemes.

We use four-wave mixing to measure the correlation coefficient of comb tones in a quantum-dash mode-locked laser under passive and active locked regimes. We study the uncertainty in the measurement of the correlation coefficient of the proposed method.

A multi-GHz chaotic optoelectronic oscillator based on an external cavity semiconductor laser (ECL) is demonstrated. Unlike standard optoelectronic oscillators for microwave applications, we do not employ the dynamic light output incident on a photodiode to generate the microwave signal, but instead generate the microwave signal directly by measuri...

We demonstrate transmission of a 200-Gb/s superchannel over 3-km single-mode optical fiber (SMF) targeting intra-data center interconnect applications using a novel single-section quantum-well passive-mode-locked laser that generates an optical frequency comb. The transmitted optical signal consists of 16 subcarriers filtered from the optical frequ...

We present a simultaneous measurement of the route to chaos of the optical intensity and carrier density as the feedback strength is increased in an external cavity semiconductor laser (ECL).

We present a regular fiber based THz spectrometer, which is driven by a monolithic semiconductor laser. Clean THz pulses with frequency components up to 0.9 THz can be generated with this ultra-compact light source.

We demonstrate Tbit/s transmission with a Q-Dash mode-locked laser using coherent detection. The aggregate capacity achieved with PDM-QPSK was 1.8Tb/s over 50km of SSMF, using 36 channels from the 34.5GHz FSR Q-Dash PMLL.

We aim at realizing an optically-pumped, dual-frequency VECSEL at telecom wavelength (1.5 µm) with a frequency difference in the radio-frequency (RF) range (around 11 GHz), to be used in a sensor unit based on Brillouin scattering in optical fibers. Laser emission of two orthogonally-polarized cavity modes with a controlled frequency difference is...

This paper reports on the repetition frequency stability of InAs/InP quantum-dash based mode locked lasers emitting in the 1.55 μm telecom window and of a long-term frequency stabilization schemes. We discuss the main noise sources that affect the frequency stability. In free running operation, quantum-dash based mode locked lasers demonstrate an i...

Successful use of a single-section quantum well (QW) passively mode-locked laser (MLL) as a comb source for optical interconnects is demonstrated for the first time. Sixteen comb lines spaced by 37.6 GHz are modulated using 25 Gb/s compatible single sideband orthogonal frequency division multiplexed (SSB-OFDM) signals and transmitted over 50 km of...

The authors demonstrate single-polarisation WDM transmission with capacities higher than 400 Gb/s and 1 Tb/s, and show the possibility of obtaining capacity in excess of 4 Tb/s for interconnect applications within and between data centres, based on a single laser source. Quantum Dash (Q-Dash) passively mode-locked lasers (PMLLs), with free spectral...

We demonstrate 400Gb/s and Tbit/s transmission using Q-Well and Q-Dash mode locked laser comb sources respectively. The aggregate capacities achieved were 473.6Gb/s for 37.6GHz Q-Well device, and 1.344Tb/s for 44.7GHz Q-Dash device using IM/DD-SSB-OFDM.

We demonstrate passive mode locking of a GaSb-based diode laser emitting at 2.1?μm. The active region of the studied device consists in two 10-nm-thick GaInSbAs/GaAlSbAs quantum wells. Passive mode locking has been achieved in a two-section laser with one of the sections used as a saturable absorber. A microwave signal at 20.6GHz, measured in the e...

By comparison to a stable reference laser, the phase noise of a frequency comb from a quantum-dash mode-locked laser can be compensated. The quality of the resulting carriers allows the transmission of data at a rate of 1 Tbit/s in a single polarization over a distance of 75 km using a standard forward error correction.

We transmit 18 GBd 16QAM signals on 25 spectral lines of a quantum-dash mode-locked laser diode, achieving a 1.562 Tbit/s aggregate data rate. Phase noise is cancelled by self-homodyne detection using LO tones transmitted with the signal.

A feed-forward heterodyne scheme is shown to simultaneously reduce the phase noise of many comb lines from a quantum-dash mode-locked laser diode (QD-MLLD). This enables the first coherent data transmission using QD-MLLD as multi-wavelength source.