BARRIER STRAIN INFLUENCE ON THE HIGH-SPEED PROPERTIES OF COMPRESSIVELY STRAINED INGAASP MULTI-QUANTUM-WELL LASER STRUCTURES

We report on an extensive experimental study of the barrier strain inf luence on the high-speed properties of compressively strained quaterna ry (InGaAsP) multiquantum-well (MQW) lasers emitting at 1.55 mu m, In the design of strained MQW laser structure emitting at 1.55 mu m, the main effect of varying the barrier strain amount is to modify the effe ctive well/barrier height for both electrons and holes, In this paper, it is shown experimentally from MQW structures with different barrier strain values, that a strong decrease of the nonlinear gain coefficie nt can be obtained when the barrier strain is reduced, leading to quan tum-well (QW) laser structures with a damping coefficient (called the K-factor) as low as 0.18 ns, i.e., theoretical damping limited bandwit h as high as 50 GHz. This result appears to be qualitatively well expl ained by a substantial reduction of the carrier capture time to escape time ratio, due to an increase of the well/barrier offset in the cond uction and valence bands.