Effect of the number of quantum wells in the active region on the linearity of the light-current characteristic of a semiconductor laser

The light-current characteristic of a semiconductor laser with multiple quantum wells (QWs) is calculated, with the delayed capture of charge carriers from the waveguide region into the wells taken into account. It is shown that increasing the number of QWs is a more effective way to improve the power characteristics of a laser, compared with an increase in the velocity of carrier capture into each of the wells. For example, using two QWs as the active region leads to a substantial increase in the internal quantum efficiency of stimulated emission and to a significantly better linearity of the light-current characteristic of the laser, compared with a single-well structure. At the same time, using three or more QWs only slightly improves the power characteristics of the laser, compared with the double-well structure. Thus, a double-well structure is the optimal as regards high output power and simplicity of growth.