Generation of spacial second-harmonic in photorefrective photonic lattice

Using interference method fabricate photonic lattices in self-defocus photorefractive crystal LNbO3 : Fe. We had find the phenomenons that dual-beam interference fringe one divides into two,four-beam interference fringe one divides into four. We had proved it is a kind of phenomena of spacial frequency- doubling, this kind of phenomenon is the result of the interaction between the interfere field and the interfere field fabricative photonic lattices. This experiment had showed that spacial second-harmonic generation and high-order harmonics generation can be easy achieved by photorefractive effect crystal,that second-harmonic can fabricate spacial frequency-doubling photonic lattices, that high-order harmonics can fabricate spacial frequency-high photonic lattices.