This paper summarizes recent advances on InAs/InP quantum dashes (QD) materials for lasers and amplifiers, and QD device performance with particular interest for optical communication. We investigate both InAs/InP dashes in a barrier and dashes in a well (DWELL) heterostructures operating at 1.5 µm. These two types of QDs can provide high gain and low losses. Continuous-wave room-temperature lasing operation on ground state of cavity length as short as 200µm has been achieved, demonstrating the high modal gain of the active core. A threshold current density as low as 110 A/cm 2 per QD layer has been obtained for infinite-length DWELL laser. An optimized DWELL structure allows achieving of a T0 larger than 100 K for broad area lasers and of 80 K for single transverse mode lasers in the temperature range between 25°C and 85°C. Buried ridge stripe type single mode DFB lasers are also demonstrated for the first time, exhibiting a side-mode suppression-ratio as high as 45 dB. Such DFB lasers allow the first floor free 10 Gb/s direct modulation for back-to-back and transmission over 16 km standard optical fiber. In addition, novel results are given on gain, noise and four wave mixing of QD-based semiconductor optical amplifiers. Furthermore, we demonstrate that QD FP lasers, owing to the small confinement factor and the 3D quantification of electronic energy levels, exhibit a beating linewidth as narrow as 15 kHz. Such an extremely narrow linewidth, compared to their QW or bulk counterparts, leads to the excellent phase noise and time jitter characteristics when QD lasers are actively mode-locked. These advances constitute a new step towards the application of QD lasers and amplifiers to the field of optical fiber communications.

In this article, self-pulsation (SP) in a distributed Bragg reflector semiconductor (DBR) laser without saturable absorber is experimentally and theoretically investigated. Detailed presentation of the device structure is given. A complete experimental investigation of the (SP) has demonstrated phase correlation between the longitudinal modes selected by the DBR mirror. The origin of the self-pulsation has been investigated theoretically. A model based on the rate equations of three coupled modes and carrier density has been developed to study the time evolution of phases and amplitudes of the modes. The carrier density modulation, resulting from the beating between adjacent longitudinal modes, generates four wave-mixing. This four-mixing process is responsible for mutual injection locking, leading to passive mode-locking. The calculated power spectral density of frequency noise derived from the model is in agreement with experimental results and proves that the phases of the longitudinal modes are identically correlated through the four-wave-mixing in this type of self-pulsating laser.