Abstract

A variety of coherent phenomena can be observed in optical experiments when a laser pulse coherently excites two or more levels. Recently, quantum beats due to charge oscillations have been observed in terahertz (THz) emission in double¹ and single² coupled quantum wells (QWs). Although these heterostructures are different, they can be regarded as three level systems if many body effects and carrier dispersion are neglected. The laser pulse excites a coherent superposition of the upper two energy levels, which then leads to quantum beats with a time varying far infrared dipole moment and this in turn gives rise to the terahertz radiation.

© 1993 Optical Society of America