Optical Lattices Achieved by Excitons in Periodic Quantum Well Structures

Photoluminescence and linear optical response from large-number multiple quantum well structures, with a period in the vicinity of half the exciton resonance wavelength, are dominated by the normal modes of the coupled wells. These show up in multiple linesplitting and a photonic band gap at Bragg resonance. The photonic gap is identified by an enhanced Bragg reflection and a corresponding weak absorption of the optical lattice. The strongly modified light-matter interaction for photons in the photonic gap is also manifest in the poor emission from the so-called super-radiant mode after excitation in the free carrier continuum.