Giant enhancement of second harmonic generation in poled ferroelectric crystals

The authors propose a simple one-dimensional inhomogeneous system composed of periodically alternating stacked air and poled LiNbO3 crystal layers. This structure combines the advantages of photonic band gap (PBG) structures and periodically poled ferroelectric crystals, so the high density of modes and quasiphase matching can be achieved simultaneously. They find that compared with simple quasiphase-matched and PBG structures, the conversion efficiency of second harmonic generation in this structure can be significantly enhanced when the pump and second harmonic fields are both tuned to the band edge.