We propose and demonstrate a novel method for recording second-harmonic volume index gratings in photorefractive crystals. The fundamental component of the index grating is eliminated by means of a π -phase shifted double-exposure process that uses the Mach–Zehnder interferometric technique. Experimental results for (K0.5 Na0.5) 0.2(Sr> 0.75Ba 0.25)0.9Nb 2O6 crystals are presented and discussed.
© 1999 Optical Society of America
(050.1940) Diffraction and gratings : Diffraction
(050.2770) Diffraction and gratings : Gratings
(050.5080) Diffraction and gratings : Phase shift
(160.5320) Materials : Photorefractive materials
Xiaonong Shen, Jianhua Zhao, Ruibo Wang, Xianmin Yi, Pochi Yeh, and Huanchu Chen, "Recording of second-harmonic index gratings in photorefractive (K0.5 Na0.5)0.2 (Sr0.75 Ba0.25)0.9 Nb2O6 crystals," Opt. Lett. 24, 312-314 (1999)