Magnetic field induced nutation of exciton-polariton polarization in (Cd,Zn)Te crystals

Abstract

We study the polarization dynamics of exciton-polaritons propagating in sub-mm thick (Cd,Zn)Te bulk crystals using polarimetric time-of-flight techniques. The application of a magnetic field in Faraday geometry leads to synchronous temporal oscillations of all Stokes parameters of an initially linearly or circularly polarized, spectrally broad optical pulse of 150 fs duration propagating through the crystal. Strong dispersion for photon energies close to the exciton resonance leads to stretching of the optical pulse to a duration of 200−300 ps and enhancement of magneto-optical effects such as the Faraday rotation and the non-reciprocal birefringence. The oscillation frequency of the excitonpolariton polarization increases with magnetic field B, reaching 10 GHz at B ∼ 5 T. Surprisingly, the relative contributions of Faraday rotation and non-reciprocal birefringence undergo strong changes with photon energy, which is attributed to a non-trivial spectral dependence of Faraday rotation in the vicinity of the exciton resonance. This leads to polarization nutation of the transmitted optical pulse in the time domain. The results are well explained by a model that accounts for Faraday rotation and magneto-spatial dispersion in zinc-blende crystals. We evaluate the exciton g-factor |gexc| = 0.2 and the magneto-spatial constant V = 5 × 10 −12 eVcmT −1 .

Ultrafast dynamical response of the lower exciton-polariton branch in CdZnTe

“…For the present temperature and excitation density we find T 2 ∼ 10 ps. We note that this time scale is reasonable, as /T 2 = 66 μeV is consistent with the value of ∼10 μeV estimated from transmission spectra at lower temperatures (T = 2K) [15].…”

Magnetospatial dispersion of semiconductor quantum wells

“…Therefore they contribute to different effects and can be distinguished by a proper choice of experimental geometry. MSD has been demonstrated in reflection and transmission experiments on various bulk semiconductors: GaAs [5], CdSe [6], ZnTe, CdTe [7], CdZnTe [8], thin films [9], magnetic semiconductors [10], as well as in the second optical harmonics generation in ZnO [11]. Here we report on the observation of MSD in quantum well structures.…”

Эффекты Магнитного Поля В Экситонной Генерации Оптических Гармоник

“…Дисперсионную зависимостьñ можно найти, используя основное соотношениеñ 2 =ε . Комплексная диэлектрическая функцияε для 1s-экситона может быть записана как [40]:…”