The THz Kerr effect measures the birefringence induced in an otherwise isotropic material by a strong THz pulse driving the Raman-active excitations of the systems. Here we provide experimental evidence of a sizable Kerr response in insulating SrTiO3 due to infrared-active lattice vibrations. Such a signal, named the ionic Kerr effect, is associated with the simultaneous excitation of multiple phonons. Thanks to a theoretical modeling of the time, polarization, and temperature dependence of the birefrengence, we can disentangle the ionic Kerr effect from the off-resonant electronic excitations, providing an alternative tunable mechanism to modulate the refractive index on ultrashort timescales via infrared active phonons.
Terahertz ionic Kerr effect. Two-phonon contribution to the nonlinear optical response in insulators / Basini, M.; Udina, M.; Pancaldi, M.; Unikandanunni, V.; Bonetti, S.; Benfatto, L.. - In: PHYSICAL REVIEW. B. - ISSN 2469-9950. - 109:2(2024), pp. 1-10. [10.1103/physrevb.109.024309]
Terahertz ionic Kerr effect. Two-phonon contribution to the nonlinear optical response in insulators
Udina, M.
Co-primo
;Benfatto, L.Ultimo
2024
Abstract
The THz Kerr effect measures the birefringence induced in an otherwise isotropic material by a strong THz pulse driving the Raman-active excitations of the systems. Here we provide experimental evidence of a sizable Kerr response in insulating SrTiO3 due to infrared-active lattice vibrations. Such a signal, named the ionic Kerr effect, is associated with the simultaneous excitation of multiple phonons. Thanks to a theoretical modeling of the time, polarization, and temperature dependence of the birefrengence, we can disentangle the ionic Kerr effect from the off-resonant electronic excitations, providing an alternative tunable mechanism to modulate the refractive index on ultrashort timescales via infrared active phonons.File | Dimensione | Formato | |
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