The effective χ(2) grating responsible for second-harmonic generation in bulk glasses was spatially resolved with a charge-selective etching technique. We observed a spatially varying structure with a period equal to the coherence length of the material. The measured period of the grating showed excellent agreement with the expected value. In addition, cross-sectional etching patterns show that in this regime of encoding intensities the flux responsible for the intense electric field is not unidirectional as predicted by most models.
© 1996 Optical Society of America
Jae H. Kyung and N. M. Lawandy, "Direct observation of the effective χ(2) grating in bulk glasses encoded for second-harmonic generation," Opt. Lett. 21, 632-634 (1996)