Frequency doubling of a 684 nm laser diode in a first-order periodically poledLiTaO3is presented. Controlling the side growth of the domain inverted region during high-voltage pulse application, a uniform nonlinear grating with a period of 1.7 &mgr;m and 50&percent; duty cycle was fabricated over 10 mm interaction length in a 150 &mgr;m thickLiTaO3substrate. A 342 nm wavelength of harmonic ultraviolet light was generated in a single pass through the domain-inverted structure. ©1997 American Institute of Physics.