Laurent Chusseau

Dynamic behaviors of semiconductor lasers under strong sinusoidal current modulation: modeling and experiments at 1.3 mu m

The theoretical analysis is based on rate equations including gain-compression effects. General criteria are established to predict the existence of irregular behaviors. Experiments are performed on a single-mode buried-heterostructure InGaAsP laser at 1.3 mu m. An original method is proposed to evaluate the parameters of the rate equations. Fully optical measurements are used. The nonlinear gain coefficient and the electrical response of the packaged laser are simultaneously determined from small-signal characteristics. Time-domain measurements show the three behaviors achieved with the laser, i.e., simple periodic, periodic with multiple spikes, and periodic doubling. Excellent agreement is found between experiments and calculations. Frequency-domain measurements are focused on distortions in periodic regimes. A quantitative limit of perturbation theories is given which corresponds to a second-order harmonic level exceeding -15 dB. >

Period doubling in directly modulated InGaAsP semiconductor lasers

We report on period doubling in a directly modulated InGaAsP semiconductor laser at 1.3 μm. This behavior is obtained for modulation frequencies between fr and 1.6fr, where fr is the laser resonant frequency measured under weak current modulation. The domain of period doubling as well as the time responses of the optical output is well interpreted using a rate equation model.

Electro-optic sampling of GaAs circuits using semiconductor lasers

Abstract Picosecond optical pulses produced by a gain-switched 1.5 μm semiconductor laser with fibre compression are used in internal electro-optic sampling of GaAs circuits. A measurement bandwidth of 60 GHz and a 20 mV voltage resolution are demonstrated.

Automatic Full Noise Characterization of Microwave GaAs FETs

A new electronically controlled input tuner is proposed for microwave device noise parameter characterization. The design and performance of this tuner are discussed. A large set of reflection coefficient equally spaced in Smith chart is produced using only frequency and power attenuation changes. High reproducibility is performed by avoiding mechanical shift. A broadband automatic noise parameters test set is realized using the proposed tuner, and applications to the full noise characterization of GaAs microwave ion-implanted MESFET are given.

Diodes lasers en régime de forte modulation sinusoïdale de courant : modélisation et expériences â 1,3 µm

RésuméLes auteurs présentent une étude théorique et expérimentale de diode laser soumise â une forte modulation sinusoïdale de courant dans le cas où la diode est polarisée au-dessus du seuil. Une première partie théorique décrit les différents comportements en régime de forte modulation. Les lasers GaAs et InGaAsP sont comparés. Les simulations numériques montrent que l’existence de comportements anormaux (doublement de période, chaos,...) peut être prédite â partir de la réponse en faible signal du laser. La seconde partie, donne les résultats expérimentaux obtenus sur un laser InGaAsP 1,3 µm et les compare avec les calculs théoriques d’un modèle â taux de population. Ce type de laser ne présente pas de comportements anormaux, mais des effets de distorsion apparaissent â fort signal. Les spectres calculés de la réponse en intensité du laser sont en excellent accord avec ceux mesurés, ce qui valide â la fois l’emploi du modèle â taux de population et le choix des paramètres lasers. L’analyse spectrale â la fréquence optique montre par contre que l’équation de phase optique utilisée par de nombreux auteurs est incomplète et que des variations longitudinales et transversales du facteur α. doivent être prises en compte.AbstractWe present a theoretical and experimental study of laser diodes under strong sinusoidal current modulation. Situations where the diodes are biased above threshold are considered. The first part describes different behaviors occurring under strong modulation. The GaAs lasers are compared to the InGaAsP lasers. The major result of numerical calculations shows that the existence of anomalous behaviors (period doubling, chaos,...) can be predicted from the weak-signal response of the laser. In a second part, we report on the expérimentais results obtained with an InGaAsP laser at 1.3 µ.m and their comparison with the theoretical calculations from a rate equation model. This kind of laser does not exhibit any anomalous behaviour under strong modulation, but distorsion effects occur. The calculated spectra of the laser intensity are in excellent agreement with measurements, which validates both the use of the rate equation model and the choice of the laser-parameters. In contrast, the spectral analysis at the optical frequency shows that the optical phase-equation previously used by many authors is uncomplete and that longitudinal and/or transversal variations of the α-factor have to be taken into account.

Mesure automatique des paramètres de bruit des MESFET hyperfréquences

RésuméLa réalisation d’un banc de mesure automatique des parametres de bruit des transistors hyperfréquences est développée en deux parties : (i) une nouvelle méthode d’extraction des quatre paramètres de bruit à partir d’un ensemble de mesures de facteur de bruit a des adaptations différentes est décrite. La détermination expérimentale du bruit minimal n’est plus necessaire et la sensibilité vis-à-vis des incertitudes de mesure est tres faible. (ii) Un adaptateur d’entrée commandable possédant un grand nombre de positions etalonnees tres reproductibles est concu et realise. La derniére partie donne des exemples de caractérisation a large bande (de 8 à 17 GHz) deMesfet GaAs concus pour les circuits integres monolithiques lorsque l’adaptateur commandable et la méthode d’extraction sont utilises conjointement.AbstractAn automatic noise parameter measurement test set is described in two sections : (i) A novel noise parameter extraction procedure from a set of noise figure measurements is developped. The experimental minimum noise figure is no longer required and the sensitivity to measurement incertainties is found to be very low. (ii) An automatic input tuner with a large number of precalibrated and reproducible positions is designed and realized. The last part give examples of broadband (8 to 17 GHz) noise parameters characterization ofmmic GaAsmesfets when both the automatic tuner and the extraction procedure are used.