Generation of Terahertz Electromagnetic Pulses from Quantum Well Structures

Terahertz generation from semiconductor quantumwell structures pumped by a femtosecond optical pulse is studied. We propose a three-level model for the electrons and holes in the quantum wells. We then solve the coupled optical Bloch equations directly using a Runge-Kutta method and calculate the terahertz radiation field. We study optical rectification and quantum beats caused by charge oscillations in 1) a coupled quantum well in which quantum beats occur between two electron states of the coupled system and 2) a single-quantum well structure in which quantum beats occur between light-hole and heavy-hole excitons. Our theoretical results agree very well with the experimentally measured terahertz data. © 1994, IEEE.