Backswitch poling in lithium niobate for high-fidelity domain patterning and efficient blue light generation

In nonlinear optics applications employing quasiphase matching, short-pitch domain gratings are generally required for the efficient generation of vis ible and ultraviolet light. Here we introduce an improved electric-field po ling technique, which incorporates spontaneous backswitching and leads to u niform short-pitch domain structures. The total volume of backswitched mate rial, and hence the duty cycle of the backswitched domain grating, can be a ccurately controlled. First-order single-pass continuous-wave second harmon ic generation of 60 mW at 460 nm is achieved at 6.1%/W efficiency in 0.5-mm -thick 4-mu m-period backswitch-poled lithium niobate. (C) 1999 American In stitute of Physics. [S0003-6951(99)03638-4].