POLARITON SPONTANEOUS EMISSION SUPERRADIANCE AND POLARITON-IMPURITY STATES IN III-V SEMICONDUCTORS

In this paper, we study the polariton energy dispersion of two differe nt types of two-level atoms placed within a III-V semiconductor which has a polariton gap due to photon coupling to optical phonons. We empl oy the spherical harmonic representation to derive the model Hamiltoni an within the framework of the dipole resonance approximation. Two pol ariton impurity states lying within the polariton gap are found. The s pontaneous emission rate of a system with two identical two-level atom s placed within a III-V semiconductor is also studied as a function of interatomic distance when the atomic resonance frequency lies in the polariton continuous spectra. It is found that when the interatomic se paration between the atoms is small, the polariton-atom system in the symmetric state can radiate a polariton with a probability that is twi ce that of the independent or single atom case (i.e. superradiance). O n the other hand, when the polariton-atom system in the antisymmetric state, the system is prevented from radiating a polariton (i.e. subrad iance). Numerical calculations are performed for polariton-impurity st ates and polariton spontaneous decay rate of the polariton-atom system for GaAs semiconductor. (C) 1997 Elsevier Science B.V.