On the breaking of a plasma wave in a thermal plasma: II.   Electromagnetic wave interaction with the breaking plasma wave
  The structure of the density singularity formed in a relativistically large amplitude plasma wave close to the wavebreaking limit leads to a refraction coefficient which has a coordinate dependence with discontinuous derivatives. This results in a non-exponentially small above-barrier reflection of an electromagnetic wave interacting with the nonlinear plasma wave. 
Sergei V. Bulanov, Timur Zh. Esirkepov, Masaki Kando, James K. Koga,   Alexander S. Pirozhkov, Tatsufumi Nakamura, Stepan S....
physics.plasm-ph