Evolution of the optical polarization in a periodically poled superlattice with an external electric field

The polarization behavior of the electromagnetic waves under external electric field in the periodically poled optical superlattice is experimentally observed, which reveals that for the QPM wavelengths [fulfilling the quasi-phase-matched (QPM) condition] the evolution of the polarization exhibits generated paths along the Poincare sphere, but for the NQPM wavelength (not fulfilling the QPM condition) it will split into discrete paths. These phenomena are likely to promote a novel method for a precise polarization control.