We report on the fabrication and chi((2)) measurements of thin similar to 10-mu m-thick films of periodically poled LiNbO3, obtained by crystal ion slicing. The d(33) optical coefficient in the films is probed by sum-frequency generation with a short-pulse laser source at 1550 nm and compared with that of the bulk. Efficient, room-temperature TM(omega, m = 0)-to-TM(omega + omega, m = 0) mode conversion is obtained in the films. These measurements show that domain periodicity is preserved during ion implantation and that the thin films have bulklike nonlinearity and material dispersion. (C) 2000 Optical Society of America OCIS codes: 130.3730, 310.6860, 190.4390, 160.3730, 190.2620, 190.4400.