Compared with normal LN crystal (CLN) with the same composition, the lack of lithium in the near-stoichiometric LN crystal (SLN) leads to a significant reduction in lattice defects, and many properties change accordingly. The following table lists the main differences of physical properties.

Comparison of Properties between CLN and SLN

Compared with CLN with the same composition, most of the properties of SLN have been improved to varying degrees. The more important optimization includes:

(1) Whether photorefractive doping, anti-photorefractive doping or laser-activated ion doping, SLN has more sensitive performance regulation effect. Kong et al. found that when [Li]/[Nb] reaches 0.995 and the magnesium content is 1.0mol%, the photorefractive resistance of the SLN can reach 26 MW/cm², which is 6 orders of magnitude higher than that of CLN with the same composition. Photorefractive doping and laser-activated ion doping also have similar effects.

(2) As the number of lattice defects in SLN crystal decreases significantly, so does the coercivity field strength of the crystal, and the voltage required for polarization reversal decreases from about 21 kV/mm (of CLN) to about 5 kV/mm, which is very beneficial for the preparation of superlattice devices. Moreover, the electric domain structure of SLN is more regular and the domain walls are smoother.

(3) Many photoelectric properties of SLN are also greatly improved, such as electro-optic coefficient r₆₁ increased by 63%, nonlinear coefficient increased by 22%, crystal birefringence increased by 43% (wavelength 632.8 nm), blue shift of UV absorption edge, etc.

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