On the possibility of the emission of attosecond pulses owing to the interaction of counterpropagating relativistically intense laser pulses with a thin layer of a diluted plasma

A numerical experiment in which two relativistically intense laser pulses are normally incident on a layer of a diluted plasma from two opposite sides is described. The period of Langmuir plasma oscillations is much larger than the pulse duration and the product of this period by the speed of light is much larger than the thickness of the layer. A pulse propagating to the right is incident on the layer earlier than the counter pulse and carries a significant fraction of electrons or all of the electrons from the plasma. Under certain conditions, electrons form a bunch, which contains most of the electrons and has a thickness much smaller than the wavelength of light. The counter pulse perturbs the motion of the bunch and initiates the emission of a short few-cycle pulse, which propagates in the positive direction (to the right), significantly differs in structure from the counter pulse, and has a duration much smaller than the field period in laser pulses.