EXCITON POLARITONS IN LONG-PERIOD QUANTUM-WELL STRUCTURES

The distribution of the normal frequencies in the complex plane for th e exciton polaritons in a finite periodic quantum-well structure is an alyzed by matrix-theory methods. Relations governing the sums of the n ormal frequencies for polariton modes that are even and odd relative t o the center of the structure are derived. It is shown in an anti-Blag g structure, whose period equals a quarter of the optical wavelength a t the excitonic resonance frequency omega(0), that the sets of the nat ural frequencies corresponding to even and odd solutions transform int o one another upon reflection relative to the vertical line omega = om ega(0). Approximate analytical expressions are found for the natural f requencies of the ''long-lived'' and ''short-lived'' polariton modes. The relation between the shape of the optical reflection spectrum and the set of natural frequencies of the system is elucidated. (C) 1998 A merican Institute of Physics.