Ultraviolet light assisted periodic poling of near-stoichiometric, magnesium-doped lithium niobate crystals

Ferroelectric domain reversal by application of electric-fields to near-stoichiometric lithium niobate crystals containing 1.3 mol % magnesium is investigated. The +z-face of the crystal is coated with a patterned photoresist layer that yields both a structured ultraviolet light absorber and a structured electric insulator. Periodic ferroelectric domain inversion in a z-cut crystal is then achieved by combination of illumination with light of the wavelength of 334 nm that reduces the coercive field strength inside the crystal by up to 50% and application of an external electrical field. Domain patterns with a period length of 10 μm are fabricated in a 500 μm thick crystal.