It is the most difficult point for high power semiconductor lasers to improve the abilities of lasers to resist catastrophic optical damage(COD) and work characteric of LDs. According to the principle that the energy gap of film materials can be influenced by internal strain stress, direct current magnetron sputtering has been used for preparing Al_xN_y dielectric films with different stresses under different deposition conditions. Broad area semiconductor lasers with a new no-absorption window has been designed considering cavity degradation of devices, peak power output has increased by 46.5 percent for the new structural device, perpedicularity divergence angle is up to 21°, parallel divergence angle is up to 6.1°. It has been less than 0.091 percent of aging speed per thousand of the LDs after testing of 2000 h aging.