To fabricate nonabsorbing windows (NAWs) near the cavity facets can reduce the light absorption and prevent early catastrophic optical damage (COD) of the cavity facets, which is an important skill in improving the output characteristics of the high power laser diode (LD). High power 657 nm red LD wafer was epitaxied by a two-step metalorganic chemical vapor deposition (MOCVD) technique, and NAWs were fabricated by Zn impurity diffusion using a closed ampoule method. NAWs fabricated at a diffusion temperature of 550 ℃ and a diffusion time of 20 min are very effective in improving the LD’s performance. Stable fundamental mode continuous wave operation is achieved at up to 100 mW without any kinks, which is three times of the maximum output power of conventional LD without the NAWs. The slope efficiency of the LD is also improved about 23% than that of the conventional LD. At ambient temperature of 20～70 ℃, the maximum outputs of the LDs are all over 50 mW, and the calculated characteristic temperature and the lasing wavelength increment are about 89 K and 0.24 nm/℃, respectively.