Quantum dash based directly modulated lasers for long-reach access networks

International audienceWe demonstrate an innovative 10 Gbps single mode optical transmitter with the capacity of error free transmission in the range of 0 to 100kms with constant biasing conditions using a Quantum Dash Directly Modulated Laser. We use a commercially available etalon filter as passive optical filter to achieve penalty free transmission with a dynamic extinction ratio (DER) > 6dB over a large range of fiber spans

Génération de microparticules portant l'Endothelial Protein C Receptor chez les malades en sepsis sévère traités par le drotrécogin alfa

BORDEAUX2-BU Santé (330632101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Génération et détection de rayonnement aux fréquences térahertz à partir d'antennes photo-conductrices en InGaAs sur InP

Le domaine de fréquence térahertz vit une fantastique accélération, motivée par l'exploration de nombreux processus physiques dont les fréquences caractéristiques tombent dans ce domaine. La réalisation d'émetteurs et de détecteurs efficaces, de faible coût, et fonctionnant à la température ambiante représente un enjeu pour les systèmes térahertz modernes. Les antennes photoconductrices en In0,53Ga0,47As et excitées avec des impulsions lasers de longueur d'onde 1550 nm sont une solution, grâce à la disponibilité de sources optiques relativement peu onéreuses, compactes et permettant de bénéficier de la technologie optique fibrée. L'irradiation ionique de la couche semiconductrice introduit des défauts qui jouent le rôle de pièges pour les porteurs libres rendant le composant ultra-rapide. Ce travail de thèse a été tout d'abord consacré à l'étude des paramètres physiques de l'In0,53Ga0,47As irradié par des ions Br+, comme la durée des vie et la mobilité des porteurs. La réponse électrique en obscurité et sous éclairement de photoconducteurs en In0,53Ga0,47As irradié a été également étudiée. Nous avons également démontré l'efficacité des antennes photoconductrices en In0,53Ga0,47As irradié pour la génération de façon impulsionnelle, mais aussi pour la détection, de rayonnement électromagnétique aux fréquences térahertz. Une autre voie de génération de rayonnement térahertz est la génération en continu. Pour cela, nous avons développé des photomélangeurs en In0,53Ga0,47As irradié et nous avons pu démontrer la potentialité de ces dispositifs pour la génération de rayonnement par mélange hétérodyne de deux faisceaux lasers continus de longueur d'onde autour de 1550 nm.Terahertz frequency domain lives a huge acceleration motivated by the exploration of a great number of physical processes, of which characteristic frequencies are in this domain. The conception of efficient and low cost emitters and detectors, operating at room temperature, is a real challenge for modern terahertz devices. In0.53Ga0.47As photoconductive antennas exciting with laser pulses at 1550 nm wavelength are a solution, because low cost and compact laser sources, providing fibre optic technology, are available. The ionic irradiation of the semiconductor layer introduces defects that act as traps for free carriers leading to an ultrafast device. This thesis work has been first devoted to the study of the Br+-ion-irradiated In0.53Ga0.47As physical parameters, as the lifetime and the mobility of the carriers. Dark and illuminated electrical responses of the irradiated In0.53Ga0.47As photoconductors have been also studied. We have also demonstrated that irradiated In0.53Ga0.47As photoconductive antennas are efficient for the impulsionnal generation, but also for the detection, of electromagnetic radiations at terahertz frequencies. Another way to generate terahertz radiations is the continuous generation. For that purpose, we have developed photomixers in irradiated In0.53Ga0.47As and we have demonstrated the potentiality of these devices for the generation of radiation by heterodyne mixing of two continuous laser beams at a wavelength around 1550 nm.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Emission characteristics of ion-irradiated In0.53Ga0.47As based photoconductive antennas excited at 1.55 µm

International audienceWe present a detailed study of the effect of the carrier lifetime on the terahertz signal characteristics emitted by Br+-irradiated In0.53Ga0.47As photoconductive antennas excited by 1550 nm wavelength femtosecond optical pulses. The temporal waveforms and the average radiated powers for various carrier lifetimes are experimentally analyzed and compared to predictions of analytical models of charge transport. Improvements in bandwidth and in average power of the emitted terahertz radiation are observed with the decrease of the carrier lifetime on the emitter. The power radiated by ion-irradiated In0.53Ga0.47As photoconductive antennas excited by 1550 nm wavelength optical pulses is measured to be 0.8 μW. This value is comparable with or greater than that emitted by similar low temperature grown GaAs photoconductive antennas excited by 780 nm wavelength optical pulses

Terahertz radiation generated and detected by Br+-irradiated In0.53Ga0.47As photoconductive antenna excited at 800 nm wavelength

The authors investigate the generation and the detection of terahertz radiation by Br+-irradiated In0.53Ga0.47As photoconductive antennas using an optical excitation at 800nm wavelength. The detected temporal wave form presents a full width at half maximum of 650fs. The signal-to-noise ratio and frequency range of the emitted terahertz radiations are similar to those emitted by low-temperature-grown GaAs photoconductive antennas. The dependences of terahertz wave form amplitude on optical pump power for both Br+-irradiated In0.53Ga0.47As and low-temperature-grown GaAs photoconductive antennas are investigated and compared

Long reach Quantum Dash based transceivers using dispersion induced by passive optical filters

International audienceWe investigate the small signal frequency response for a low chirp Quantum Dash directly modulated laser in combination with an off-the-shelf passive optical filter. We report the enhancement of channel-bandwidth and the eye reshaping using such a transmitter assembly that allows transmitting 10 Gbit/s signal from 0 km up to 100 km using constant bias conditions

Monolithic integration on InP of a DML and a ring resonator for future access networks

International audienceThe future technology migration in access networks compels the development of key innovative transmitters operating at 10 Gb/s around 1550 nm and capable of transmitting data in extended reach passive optical networks (>60 km). A laser modulated directly appears to be a low cost and a simple solution to address these needs. However, the extinction ratio and the distance of transmission are limited by frequency chirping inherent to high bit rate modulation at 1550 nm. In this letter, we demonstrate the monolithic integration of a directly modulated lasers and a ring resonator (RR) and show the possibility to engineer the RR with specific frequency modulation efficiency. The ring is used as an optical eye reshaper, which enables the increase of the extinction ratio above 9 dB. Transmissions up to 65 km with 5.8 dBm of modulated optical power coupled into the fiber are demonstrated, proving the feasibility of our transmitter for the next generation passive optical network stage