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Recent progress in the field of quantum dot/dash based semiconductor optical amplifiers (SOAs) for slow and fast light is discussed. Room temperature fast light has been obtained in InAs/InP QDash based SOAs by means of coherent population oscillation and four wave mixing (FWM) effects. Typical optical delays amount to 55 ps at 2 GHz. Growth optimization of the QDashes allowed us to achieve high modal gain, leading to very similar performances, e.g. gain and FWM efficiency, to those of a bulk SOA. A novel approach based on linear spectrograms is also introduced to measure the phase shift induced by wave mixing in an SOA.

International audience; Quantum-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.

A new laser suitable for access-systems with FM efficiency up to 7 GHz/mA and negligible amplitude modulation is presented. It enables 1.25/2.5 Gb/s operations with extremely low driving signals: 70 mV pk-pk and 250 mV pk-pk respectively.

Measurement of the Henry factor over large optical bandwidth is carried out in a single step without any filtering, using a technique based on the sinusoidal phase modulation method. This fast technique was successfully applied to a directly modulated Fabry Perot laser to obtain simultaneously the linewidth enhancement factor (LEF) of 14 longitudinal modes. It is also well suited for electro-absorption modulators (EAM) for which the α-factor is determined over 15 nm optical bandwidth. A very good agreement is found with the well established fiber transfer function method.

The performances of a novel low-chirp electroabsorption modulator laser module are presented. Transmission is analysed in standard singlermode fibre at 40 Gbit/s. Propagation without chromatic dispersion compensation up to 2 km exhibits a low penalty variation over a wide temperature range. A propagation scheme with compensation leads to negligible impairment at 88 km.

Optical pulses generated by an electroabsorption modulator are experimentally compressed in various negative-dispersion fibres. Theoretical and experimental pulsewidth evolutions are shown to be in excellent agreement when the voltage-dependent transmission and chirp functions are taken into account.

The variability of optical frequency modulation with electric field in an electro-optical phase section is analysed. When configured for maximum sensitivity, the electro-optical phase section was used to compensate for the chirp of the gain section: 48 ps and 8.5 GHz wide transform-limited pulses were obtained at 5 GHz.

Dynamic measurements of the Henry factor alpha H of InAs/GaAs Fabry-Perot lasers are compared for 3-, 5- and 10-QD layers. While alpha H dramatically increases with the bias current for 3- and 5-QD stacks, it only amounts to

High frequency characterisation of three-quantum well GaInNAs/GaAs lasers operating at 1.35 µm is reported. A relaxation frequency as high as 7.4 GHz and a 9.7 GHz small-signal bandwidth are demonstrated, indicating the potential for high bit rate (10 Gbit/s) direct modulation of these dilute nitrides on GaAs devices.

For short and medium reach network applications, a low-cost and high performance integrated laser-electroabsorption modulator source for 1.5 µm transmissions is proposed. Coolerless and isolator-free 10 Gbit/s transmission over 50 km, for temperature ranging from 10 to 80°C is demonstrated.

Small-signal frequency modulation response and chirp characteristics of a tunable, optically-pumped 1.6 µm vertical cavity surface emitting laser (VCSEL) based on microelectromechanical at wavelength tuning are presented for the first time. From the measurements the linewidth enhancement factor αH has been derived and is discussed.

High frequency FM sources are realised with a butt-jointed intracavity superlattice modulator in DBR lasers. They exhibit good lasing parameters and a 3 dB bandwidth up to 4 GHz is obtained with a modulated voltage control in the phase section.

A linewidth as narrow as 70 kHz together with a linewidth-power product of 0.2 MHz.mW have been achieved on 1450 mu m long compressively strained quantum well uniform DFB lasers. The results are achieved through a reduction of the phase-amplitude coupling factor, which is measured to be 1.7 times lower than in unstrained devices. >