Barrier strain influence on the high-speed properties of compressively strained InGaAsP multiquantum-well laser structures

We report on an extensive experimental study of the barrier strain influence on the high-speed properties of compressively strained quaternary (InGaAsP) multiquantum-well (MQW) lasers emitting at 1.55 /spl mu/m. In the design of strained MQW laser structure emitting at 1.55 /spl mu/m, the main effect of varying the barrier strain amount is to modify the effective 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 coefficient can be obtained when the barrier strain is reduced, leading to quantum-well (QW) laser structures with a damping coefficient (called the K-factor) as low as 0.18 ns, i.e., theoretical damping limited bandwidth as high as 50 GHz. This result appears to be qualitatively well explained by a substantial reduction of the carrier capture time to escape time ratio, due to an increase of the well/barrier offset in the conduction and valence bands.