Signature of resonant Rayleigh scattering from microcavity polaritons: Angularly peaked coherent emission

Summary form only given. We unambiguously identify resonant Rayleigh scattering in a semiconductor microcavity using ultrafast spectral interferometry and demonstrate that this coherent emission is restricted to a cone defined by the excitation wave-vector, in contrast to isotropic luminescence. The sample is a /spl lambda/ GaAs cavity with a single 8 nm Ga/sub 0.96/In/sub 0.04/As quantum well at the anti-node, surrounded by two Ga/sub 0.9/Al/sub 0.1/As/AlAs Bragg mirrors.