Single-cycle attosecond pulses by Thomson backscattering of terahertz pulses

The generation of single-cycle attosecond pulses based on Thomson scattering of terahertz (THz) pulses is proposed. In the scheme, a high-quality relativistic electron beam, produced by a laser-plasma wakefield accelerator, is sent through suitable magnetic devices to produce ultrathin electron layers for coherent Thomson backscattering of intense THz pulses. According to numerical simulations, single-cycle attosecond pulse generation is possible with up to 1 nJ energy. The waveform of the attosecond pulses closely resembles that of the THz pulses. This allows for flexible waveform control of attosecond pulses.