Slow and superluminal light in semiconductor optical amplifiers

Introduction: Optical buffer via optically controlled slow light propagation is highly desirable for numerous applications, including all-optical true time delay, signal processing and storage. The device is based on optically controlled dispersion, which leads to the possibility to control the group velocity. An all-optical buffer based on electromagnetically-induced transparency in quantum dots has been theoretically considered [1]. Recently, slow light via coherent population oscillation in quantum wells has been demonstrated [2]. In this Letter, we analyse the possibility of realisation of slow and ‘superluminal’ light in semiconductor optical amplifier (SOA) via wave-mixing. Dynamics of carrier density and of the carrierdependent refractive index leads to the nonlinear dispersion, and the possibility of slow and ‘superluminal’ light.