Linear and nonlinear semiconductor optical amplifiers

Two selected applications of semiconductor optical amplifiers (SOA) are discussed, namely linear in-line amplification in gigabit passive optical networks and fast nonlinear all-optical signal processing. We report on measurements demonstrating the suitability of quantum-dot (QD) and bulk SOA for the respective application areas. For in-line amplification the saturation power of the SOA should be large, while it has to be low for efficient signal processing. For bulk SOA we find by physically-based simulations that at large injection currents and for a fixed gain, p-doping (n-doping) of the active layer increases (decreases) the saturation power. Recently published experiments show that qualitatively these results carry over to QD-SOA.