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

We report an extensive experimental study of barrier strain influence on high speed properties of compressively strained quaternary (InGaAsP) multi-quantum well DFB lasers emitting at 1.55 /spl mu/m. It is experimentally shown that a strong decrease of nonlinear gain coefficient can be obtained by reducing the barrier strain, leading to quantum well laser structures with damping coefficient as low as 0.18 ns, i.e. intrinsic bandwidth as high as 50 GHz. This result is explained by a substantial reduction of carrier capture time to escape time ratio, due to an increase of the well/barrier offset between the conduction and valence bands.