Anomalous enhancement of the optical nonlinearities in quantum paraelectric SrTiO/sub 3/

Summary form only given. Strontium titanate (SrTiO/sub 3/) is a typical dielectric material with perovskite-type structure. The crystal structure is cubic above T/sub c/=105 K, where SrTiO/sub 3/ undergoes structural phase transition at zone boundary. Below T/sub c/, the crystal structure changes into tetragonal with keeping a center of symmetry. Strong electron phonon coupling is expected from the optical properties. Optical nonlinearity in such an exotic material is quite interesting subject to research. Optical nonlinearity in such an exotic material is quite interesting subject to research. Second-harmonic generation (SHG) and optical Kerr-effect (OKE) were measured by femtosecond laser pulses.