Theory of THz emission from optically excited semiconductors in crossed electric and magnetic fields

The coherent transients generated by femtosecond interband photoexcitation of a semiconductor in crossed electric and magnetic fields are calculated. The scattering with LO phonons is considered and the complex interplay between excitation and dephasing is analyzed. While below the LO-phonon threshold the signal is not effectively damped, above the threshold damping takes place on a picosecond time scale, in qualitative agreement with corresponding experiments.