Resonant and surface polaritons in quantum wells |
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Authors: | F Tassone F Bassani LC Andreani |
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Institution: | (1) Scuola Normale Superiore, I-56100 Lausanne, Switzerland;(2) IRRMA, PHB-Ecublens, CH-1015 Lausanne, Switzerland |
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Abstract: | Summary We show how the breaking of the translational invariance in a quantum well modifies the concept of polariton with respect
to that defined for bulk material. Polaritons in quantum wells result from the combination of the exciton states with the
radiation field. They are here obtained as the solutions of Maxwell equations with retardation, provided an appropriate nonlocal
response function is used for the electric susceptibility, and Maxwell boundary conditions are imposed. We find two types
of polaritons depending on the values of the in-plane wavevectork
II: those atk
II<ω/v (wherev=c/n is the velocity of light in the sample) are resonant with the radiation field in the barrier and those atk
II>ω/v cannot be coupled to waves in the barrier. In both cases explicit expressions are given for radiative shifts and radiative
broadenings as functions ofk
II. Numerical results are obtained for GaAs-Ga1−x
Al
x
As and for CuCl quantum wells and new experiments are suggested. The existence of resonant and surface polaritons justifies
an interpretation of the temperature dependence of the radiative lifetime suggested by the same authors. It also decreases
the radiative efficiency in the direction perpendicular to the planes and increases the radiative efficiency parallel to the
planes with increasing temperature.
Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction. |
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Keywords: | Excitons and related phenomena (including electron-hole drops) |
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