Two waveguide layers in lithium niobate crystal formed by swift heavy Kr ion irradiation*
Liu Taoa),b), Huang Qingc), Zhao Jin-Huad), Kong Wei-Jina),b), Liu Penge), Zhang Liane), Zhou Yu-Fane), Yu Xiao-Feie), Wang Leie), Wang Xue-Line)†
       
(a) Micro-Raman spectra recorded in the x -cut LN crystal and the irradiated layer; (b) the enlarged Raman peak at approximately 872 cm−1 A 1(LO) in the Kr-ion-irradiated layer (the depths at 30 μm, 80 μm, 110 μm, 130 μm, 152 μm, 160 μm); (c) the depth profile of the intensity of the Raman peak at 872 cm−1.