Stoichiometric lithium niobate for nonlinear optical applications

Virtually all optical devices in lithium niobate use crystals of the congruent composition. The additional degree of freedom in the design of nonlinear optical devices afforded by the variable composition has not been used in practice. The authors converted slabs and single-crystal fibers of congruent lithium niobate to the stoichiometric composition and showed that the phase matching temperature for second harmonic generation (SHG) of 1.06-μm radiation is raised from 40C for congruent material to 2380C for a stoichiometric crystal. The authors describe the experiment, the results and give examples of nonlinear optical applications for lithium niobate