This book covers new research on LiNbO3 including current studies on intrinsic and extrinsic point defects and the contribution of intrinsic defects to photoinduced charge transport. Applications of this material are also discussed.

Lithium niobate, LiNbO , is an oxide ferroelectric with various kinds of pro- 3 nouncedphysicalproperties. Thisversatilityhaspromoteditscareerinscience anddevices. Ithasbeenparticularlyfruitfulintheopticalregime,wheremany e?ects have been found in LiNbO and devices introduced using it as a host. 3 One of the few big drawbacks, namely the low level laser damage threshold based on photorefraction due to extrinsic defects was discovered very early. A relatively new topic, not involved so far in any general description, is a fundamental dependence of the optical properties of LiNbO on intrinsic de- 3 fects. Their importance has been realised out due to the development of varies growthtechniquesintherecentpast. Theprogressinthegrowthandstudiesof LiNbO crystals with di?erent composition, particularly almost stoichiomet- 3 ric ones, has revealed a signi?cant and sometimes decisive role of the intrinsic defects. For example, the photoinduced charge transport, and therefore the photorefractive properties governing the recording of the phase gratings in LiNbO , are strongly controlled by the content of intrinsic defects. The re- 3 cently found impact of intrinsic defects on the coercive ?eld in LiNbO is 3 of fundamental importance for the creation of periodically poled structures (PPLN) aimed at the optical-frequency conversion in the quasi-phase mat- ing (QPM) mode of operation. As a consequence of these results, an idea of the intrinsic defects in LiNbO has been developed during the last decade 3 and involves microscopic studies on defects, photorefraction and ferroelectric switching using spectroscopic and structure methods.