Giant isolated half-cycle attosecond pulses generated in coherent bremsstrahlung emission regime

Giant half-cycle attosecond pulse generation in the coherent bremsstrahlung emission (CBE) regime is proposed for laser pulses with normal incidence on a double-foil target, where the first foil is transparent and the second foil is opaque. The presence of the second opaque target contributes to the formation of a relativistic flying electron sheet (RFES) from the first-foil target. After the RFES has passed through the second opaque target, it is decelerated sharply and bremsstrahlung emission occurs, which results in the generation of an isolated half-cycle attosecond pulse having an intensity of 1.4x10^22W=cm^2 and a duration of 3:6as. The generation mechanism does not require extra filters and may open a new regime of nonlinear attosecond science.