A method for producing an optical semiconductor device 1, wherein the substrate has a surface index of A, and the ridge and the grooves are formed such that {HEAD ~ exposed slanting surfaces} of {TAIL ~ the ridge} and the grooves have inclination angles from about 25 degrees from a surface to about 54 degrees from a surface 
A method for producing an optical semiconductor device 1 , wherein the substrate has a surface index of A , and the ridge and the grooves are formed such that { HEAD ~ exposed slanting surfaces } of { TAIL ~ the ridge } and the grooves have inclination angles from about 25 degrees from a surface to about 54 degrees from a surface
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