SEMICONDUCTOR OPTICAL AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor optical amplifier which is not influenced by a polarized light. SOLUTION: The active layer 20 of a semiconductor optical amplifier comprises the alternately combined layers of solid sub-layers which have the same bandgap width and are subjected to a tensile stress 21 and a compressive stress 22 alternately. The sub-layer 21 which is subjected to the tensile stress advantageously acts on the propagation of TM mode of the polarized light, and the sub-layer 22 which is subjected to a compressive stress advantageously acts on the propagation of TE mode of the polarized light. Moreover, the thickness of the sub-layers have the values by which a gain G for TE mode and a gain G for TM mode become positively identical.