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

Modulation and Equalization Techniques for mmWave ARoF

Fifth generation (5G) is the emerging mobile communications platform that aims to meet the market requirements in terms of enhanced broadband connectivity based on harnessing small cell and mmWave technology. These two in synergy will provide high capacity gain not only through the hyperdense deployment of small cell but also through accessing large swathes of untapped spectrum at mmWave frequencies. The envisaged architecture entails an integrated optical wireless network architecture, where optical technology will complement radio in order to handle the new demands on capacity over the backhaul and fronthaul network, leading to the notion of analog radio over fiber (ARoF). The goal of this chapter is to provide novel approaches to optimize the performances of mmWave ARoF systems that includes developing enabling technology from a digital to signal processing (DSP) and device perspective

Dynamic properties of InAs/InP(311B) quantum dot Fabry-Perot lasers emitting at 1.52-μm

International audienceDynamic properties of truly three-dimensional-confined InAs/InP quantum dot (QD) lasers obtained by molecular beam epitaxy growth on a (311)B oriented substrate are reported. The relative intensity noise and small signal modulation bandwidth experiments evidence maximum relaxation frequency of 3.8 GHz with a clear relaxation oscillation peak, indicating less damping than InAs/GaAs QD lasers. The Henry factor amounts to ∼ 1.8 below threshold and increases to ∼ 6 above threshold, which is attributed to band filling of the thick wetting layer

Measuring the Chirp and the Linewidth Enhancement Factor of Optoelectronic Devices with a Mach–Zehnder Interferometer

International audienceIn this paper, a technique based on the use of a Mach–Zehnder (MZ) interfero-meter is proposed to evaluate chirp properties, as well as the linewidth enhancement factor (alpha-H factor) of optoelectronic devices. When the device is modulated, this experimental setup allows the extraction of the component’s response of amplitude modulation (AM) and frequency modulation (FM) that can be used to obtain the value of the alpha-H factor. As compared with other techniques, the proposed method gives also the sign of the alpha-H factor without requiring any fitting parameters and, thus, is a reliable tool, which can be used for the characterization of high-speed properties of semiconductor diode lasers and electro-absorption modulators. A comparison with the widely accepted fiber transfer function method is also performed with very good agreement

Gain compression and above-threshold linewidth enhancement factor in 1.3μm InAs-GaAs quantum dot lasers

International audienceQuantum-dot (QD) lasers exhibit many useful properties such as low threshold current, temperature and feedback insensitivity, chirpless behavior, and low linewidth enhancement factor (alphaH-factor). Although many breakthroughs have been demonstrated, the maximum modulation bandwidth remains limited in QD devices, and a strong damping of the modulation response is usually observed pointing out the role of gain compression. This paper investigates the influence of the gain compression in a 1.3-mum InAs-GaAs QD laser and its consequences on the above-threshold alphaH-factor. A model is used to explain the dependence of the alphaH-factor with the injected current and is compared with AM/FM experiments. Finally, it is shown that the higher the maximum gain, the lower the effects of gain compression and the lower the alphaH-factor. This analysis can be useful for designing chirpless QD lasers with improved modulation bandwidth as well as for isolator-free transmission under direct modulation

Etude de l'injection optique intermodale dans les lasers a semi-conducteurs en regime de modulation, de blocage de mode et d'instabilites

INIST T 76942 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

STABILISATION DE LA DERIVE EN FREQUENCE DANS LES DIODES LASERS SEMICONDUCTRICES SOUMISES À UNE FORCE DE RAPPEL OPTIQUE

International audience<p>La dérive de fréquence des lasers DFB peut être stabilisée via une force de rappeloptique. L’objectif de cet article est d’expliquer et de confirmer cet effet par lasimulation numérique et de dégager des règles de sélections quantitatives afind’améliorer les performances des futurs systèmes de télécommunications optiques.</p

Frequency Chirp Stabilization in Semiconductor Distributed Feedback Lasers With External Control

International audience<p>It is well known that current modulation in diode lasers generates amplitude (AM) and optical frequency (FM) modulations. The frequency chirp under direct current modulation originates from variations in the carrier density and from the finite difference in carrier density between the laser on and off states. Modulation of the carrier density modulates the gain and the optical index causing the resonant mode to shift. This frequency chirp broadens the spectrum, which is a serious limitation for high-speed applications and optical fiber communications. At low frequencies, thermal effects also alter the frequency chirp. The aim of this paper is to show that the laser’s frequency chirp can be modified using an external control technique. The chirp response is evaluated via the determination of the chirp-to-power ratio (CPR) through a Mach-Zehnder interferometer. Experiments demonstrate that when an external optical feedback is properly adjusted, the CPR can be severely decreased over a wide range of modulation frequencies as compared to the free-running case. These preliminary results obtained on quantum well distributed feedback lasers (QW DFB) with low normalized coupling coefficient (&#1113088;L) demonstrate how to stabilize the CPR through the DFB facet phase effects or parameters such as the linewidth enhancement factor. In order to confirm this frequency chirp engineering, self- consistent calculations based on the transfer matrix method are also presented.</p

Phase-Amplitude Coupling of Optically-Injected Nanostructured Semiconductor Lasers

International audienceIn injection-locked lasers, the phase-amplitude coupling cannot be characterized by the FM-to-AM ratio. The former exhibits a resonance due to the injected field and the equivalent a-factor can be larger than that of solitary laser