Polarization Coupling of Light and Optoelectronics Devices Based on Periodically Poled Lithium Niobate

Ferroelectric crystals are important materials in many kinds of applications. Since the invention of so called quasi-phase matching technique, periodically domain-inverted ferroelectrics crystals with modulated second order nonlinear susceptibility has received much attention owing to its outstanding nonlinear optical properties(Magel et al.,1990; Xu et al.,1993; Zheng et al.,1998). In periodically domain-inverted ferroelectrics crystals, besides the nonlinear optical coefficients, other third-rank tensors, such as the electro-optic (EO) coefficient, are also modulated periodically because of the periodically reversed ferroelectric domains. Since the theoretical research on EO effect in PPLN was proposed by Y.Q Lu et al(Lu et al.,2000), this periodically modulation of the EO coefficient has given birth to some novel essential applications, especially when the voltage is applied along the transverse direction of the crystal. In this chapter, current research of transverse EO-based PPLN applications, such as tunable wavelength filter, polarization controller, electro-optical switch and laser Q-switch in periodically poled lithium niobate are summarized.