Congruent Lithium Niobate

Congruent PPLN chips can be produced with thickness up to 1mm and lengths over 50mm. The domain pattern is generated using the electrical field poling process. This allows not only single grating devices where one interaction is phase-matched, but multiple gratings along the propagation direction, chirped gratings, and fan-out gratings . Most PPLN devices fabricated from congruent.

Lithium niobate are used for difference frequency generation5 or OPO applications pumped in the near infrared, but SHG is also possible, e.g. from a fiber laser at 1.55µm.