Analytical model of waveform-controlled single-cycle light pulses from an undulator.

ABSTRACT

This Letter builds upon a recent concept [Phys. Rev. Lett.113, 104801 (2014)PRLTAO0031-900710.1103/PhysRevLett.113.104801] for producing ultrashort optical pulses through the coherent radiation of electrons in an undulator. Each pulse contains only a single oscillation cycle, and has a controlled waveform (and hence a stable carrier-envelope phase). While the concept had been demonstrated numerically, this Letter provides an analytical model for the radiation mechanism, thereby revealing three key observations (i) the correlation between the waveforms of the optical and undulator fields; (ii) the free-space dispersion of transversely confined light; and (iii) the dependence of the optical pulse shape on the undulator field strength.