Magnetic field dependence of terahertz wave generation in PPLN crystal was investigated. A ? phase shift occurs in an undoped PPLN under magnetic field at ~ 0.45 T due to photorefractive effect in PPLN crystal.

Magnetic field induced phase shift of terahertz wave in PPLN crystal was investigated with femtosecond pump-probe method. A pi phase shift occurs in an undoped PPLN with applied magnetic field reaches ~0.45 T, but in the case of MgO-doped PPLN crystal, THz phase shows magnetic field independence. The magnetic field induced pi-phase shift comes from the photorefractive effect in PPLN crystal.

Excitation photon energy and carrier density dependence of spin dynamics in bulk CdTe crystal was studied by time resolved pump-probe reflectivity technique at room temperature. The results show that spin relaxation time decreases monotonously. While with increasing excitation carrier density, the time constants increases initially then decreases after reaching a maximum value. Our experimental results reveal that both D’yakonov–Perel’ [M. I. D’yakonov and V. I. Perel’, Sov. Phys. JETP 38, 177 (1974)] and Elliot–Yafet [R. J. Elliott, Phys. Rev. 96, 266 (1954); Y. Yafet, Solid State Phys. 14, 1 (1963)] mechanisms dominate the spin relaxation process in CdTe crystal.