Nonlinear terahertz properties of n-type quantum-well heterostructures

In this letter, we study the effect of many body interactions on the collective response of confined electrons in doped quantum-well (QW) heterostructures to intense far-infrared radiation. Absorption lineshapes are computed both by numerically integrating the equations of motion and by using the appropriately time-averaged equations. For a two-subband double-QW system optical bistability is observed and its parameter range is given. For an asymmetric triple-QW structure driven at /spl omega//spl ap/E/sub 2/-E/sub 0/ Hopf bifurcations occur which generate a strong response at a frequency incommensurate with the drive frequency or any natural frequency of the system.