Optimization of barrier thickness for efficient carrier capture in graded-index and separate-confinement multiple quantum well lasers

We present results from numerical calculations on the carrier capture efficiency in separate- confinement and graded-index separate-confinement multiple quantum well (MQW) lasers. We find that the capture time oscillates as a function of the well width as well as the barrier width between the wells, due to a changing overlap of the barrier wave functions with the bound states in the wells. We show that one order of magnitude improvement in the carrier capture efficiency can be accomplished by properly choosing the dimensions of the layers in the active region of the MQW laser.