Abstract

The terahertz (THz) spectral range (λ=30-300μm) has long been devoid of efficient, narrowband, and tunable semiconductor sources. Recently, Quantum Cascade Lasers (QCLs) have been developed for this wavelength range, however they still operate only at cryogenic temperatures. An alternative way to produce terahertz radiation is difference-frequency generation (DFG) at room temperature in a nonlinear optical crystal using pumps in infrared or visible [1], It is known since the late 1980s that intersubband transitions in asymmetric coupled quantum wells display giant optical nonlinearities and can be used for DFG in TFlz [2].

© 2007 IEEE