Traveling-wave type semiconductor laser amplifier

摘要

PURPOSE:To make it possible to maintain a low operating current density, a low polarization surface dependence and high power and low noise at the same time by providing an optical wave guide layer which has a band gap larger than that of an active layer at least on one side of said active layer which tends to increase. CONSTITUTION:An optical wave guide layer 2 having a band gap larger that of an active layer 1 is provided at least on one side of the active layer 2 which tends to increase. In this manner, the optical wave guide layer 2 is provided at least on one side of the active layer 1. The installation of the wave guide layer 2 make it possible to confine light without increasing the thickness of the active layer 1. Since there is no need to increase the thickness of the active layer 1, the current density can not be increased even if an attempt is made to increase a carrier density. Furthermore, this construction can reduce the thickness of the active layer 1. It is, therefore, possible to obtain high power and low noise, maintaining a low operating current density and low polarization surface dependence as well.