Non-linear optic nutation on interexcitonic transitions in Semiconductors

P. I. Bardetskiı̆, A. Kh. Rotaru, S. D. Tiron +1 more

Tohya Hiroshima

P. I. Bardetskiı̆, M. I. Shmiglyuk, S. D. Tiron

Abstract The non‐linear optical nutation on the transitions between IS and 2P exciton states of the Cu2O yellow series is considered theoretically taking into account their degeneracy and polarization properties. The problem is solved under various initial conditions for certain definite orientations of the electrical component of the laser field that causes the interexciton transitions. It is shown that the exciton and photon concentrations vary periodically in time within a certain range near their steady equilibrium values which coincide with the stationary ones. The nutation frequencies are found. A stationary condition is obtained and the stationary frequencies and concentrations are determined.

M. I. Shmiglyuk, P. I. Bardetskiı̆, S. D. Tiron

Abstract The nonlinear nutation on the optical transitions between the IS(Λ ) and 2P(Λ , 2Λ , Λ , Λ ) exciton states of the Cu2O yellow series is studied theoretically. An idealized case is considered when one coherent excitonic mode of a macroscopic amplitude is created in the 2P(Λ ) state by the external resonant pumping. It is shown that in this case the CO2‐laser induced dipole transition scheme is the same as for the model equidistant three‐level system. The evolution of the nonstationary state of the exciton–photon system to the stationary one due to the polarization damping is considered. The phase diagrams are investigated both, at strong and weak damping.

Victor I. Klimov

Pratima Sen, P. K. Sen

Using a coherent radiation-semiconductor interaction model based upon the time dependent perturbation technique, the occurrence of optical nutation has been analytically investigated in direct-gap semiconductors such as GaAs, GaSb, InAs, and Hg1-xCdxTe, duly irradiated by near resonant laser beams. The present approach is much more simplified and straightforward than the conventional Maxwell-Bloch approach used so far for the study of coherent optical transient effects in molecular and atomic systems. The dispersion and absorption expressed in terms of the real and imaginary parts of the crystal optical susceptibility\chi_{r}and\chi_{i}exhibit temporally damped ringing behavior of Neumann and Bessel types, respectively. These processes have been identified as dispersive and absorptive optical nutation. The theory is developed for arbitrary laser intensity in presence of damping due to nonoptical processes. To understand the mechanisms of dispersive and absorptive optical nutation, we have restricted only to low-power resonant band-to-band transitions neglecting excitonic and damping effects. While studying analytically the transient behavior of\chi_{r}and\chi_{i}for a given pump field strength, it is noticed that the absorptive component exhibit remarkable qualitative agreement with the experimental observations of optical nutation in13CH3F.