Figure 1

Schematic illustrations of the fabrication procedures of a periodically proton-exchanged (PPE) LiNbO3 substrate, (a) clean substrate, (b) Cr film deposition, (c) spin coating SPR 6810, (d) photolithography, (e) Cr film etching, (f) photon exchange (200 °C, 24 h), (g) removing Cr film, (h) annealing (0, 1, 4, 9, 16) h, (i) photodeposition and (j) after photodeposition.