Optical Properties of PT‐Based Relaxor Ferroelectric Crystals

During the last two decades, PT‐based relaxor ferroelectric crystals such as (1−x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 (PZN–PT), (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT), and (1−x−y)Pb(In1/2Nb1/2)O3–yPb(Mg1/3Nb2/3)O3–xPbTiO3 (PIN–PMN–PT or PIMNT) crystals, are widely studied due to their huge piezoelectric properties and super‐high electro‐mechanical coupling factors. They have excellent properties with compositions around the morphotropic phase boundary (MPB). It is gratifying that the PT‐based relaxor crystals are replacing traditional PZT piezo‐ceramics in many application fields. Most ferroelectrics with oxygen‐octahedral structure, which show outstanding electro‐mechanical properties, also have excellent optical performances. Ferroelectric single crystals with large electro‐optic (EO) modulation are widely applied in laser communication devices. For the practical applications, the knowledge of detailed optical parameters is desirable. This paper tries to show a global review on the optical properties of PT‐based relaxor ferroelectric crystals. In the present review, optical properties of the crystals are systematically summarized, including refractive index dispersion, transmittance, band gap, EO, acousto‐optic, and photorefractive properties. These properties change with the crystal composition, orientation, and poling condition. The purpose of the review is to provide a resource for the researchers who are concerned with basic physical investigation or optical device applications of the PT‐based relaxor ferroelectric crystals. Optical properties of PZN‐PT, PMN‐PT, and PIN‐PMN‐PT (PIMNT) crystals are systematically summarized, including refractive index dispersion, transmittance, band gap, electro‐optic, acousto‐optic, and photorefractive properties. These properties change with the crystal composition, orientation, and poling condition. This review provides a resource for the researchers who are concerned with basic physical investigation or optical device applications of PT‐based relaxor ferroelectric crystals.