Patterns on semiconductors are crucial for optoelectronic microdevices in a wide variety of applications. We report here a facile photochemical method based on laser interference etching for fabrication of two-dimensional (2D) gratings and quasi-hexagonal photonic patterns on GaAs wafers. The periods of the patterns can be adjusted by tuning the incident angles without any significant change of the optical alignment. We find that the optical reflectivity of the etched samples is greatly reduced, especially for samples after three-beam interference etching with the minimum average reflectance of less than 2%, which can be easily adopted for fabricating anti-reflection layer of solar cells. Photoluminescence (PL) study shows that slightly blue shifted PL peaks can be observed due to quantum confinement effect.