DISTRIBUTED FEEDBACK SEMICONDUCTOR LASER

PROBLEM TO BE SOLVED: To provide a distributed feedback semiconductor laser, having a structure that improves the planarity of crystal layer growth in the upper layer of a diffraction grating, and further, improves the reliability of an element by reducing the density of crystal defects. SOLUTION: A first active layer 1A including a first diffraction grating 3a and a second active layer 1B including a second diffraction grating 3b are separated and arranged above and below so that the arrangement period for the first and second diffraction gratings 3a and 3b can be expanded. As a result, the area of grooves among the diffraction gratings are expanded so as to improve the removal effect of a mask material to be used during the formation of the diffraction gratings, reduce the density of internal dislocation (crystal defect), and attain the improved reliability for an element. COPYRIGHT: (C)2010,JPO&INPIT