Abstract
The characteristics of 1.55 mu m InAs self-organized quantum-dot lasers, grown on (001) InP substrates by molecular beam epitaxy, have been investigated. Modulation doping of the dots with holes and tunnel injection of electrons have been incorporated in the design of the active (gain) region of the laser heterostructure. Large values of T-0 = 227 K (5 degrees C <= T <= 45 degrees C) and 100 K (45 degrees C < T <= 75 degrees C) were derived from temperature dependent measurements of the light-current characteristics. The modal gain per dot layer is 14.5 cm(-1) and the differential gain derived from both light-current and small-signal modulation measurements is similar to 0.8 x 10(-15) cm(2). The maximum measured -3 dB small-signal modulation bandwidth is 14.4 GHz and the gain compression factor is 5.4 x 10(-17) cm2. The lasers are characterized by a chirp of 0.6 angstrom for a modulation frequency of 10 GHz and a near zero a-parameter at the peak of the laser emission. These characteristics are amongst the best from any 1.55 mu m edge-emitting semiconductor laser.