Disclosed is a method of laser irradiation of a patterned semiconductor device including a periodic array of sub-wavelength fin-like structures, all fin-like structures upstanding from a base face of the semiconductor device and defining an upper face of the periodic array opposite the base face, each fin-like structure having: a width along a first direction parallel to the base face of the order of magnitude or smaller than the laser wavelength; a length along a second direction parallel to the base face and perpendicular to the first direction at least 3 times greater than the width; and a height along a third direction perpendicular to the base face. The method includes: generating a UV pulsed laser beam using a laser module; and irradiating at least a portion of the upper face with the laser beam.