Modeling of THz quantum cascade lasers for room temperature operation
The terahertz frequency region spans the range between 0.3 and 10 THz. There is a considerable need for practical THz sources, notably for defence-oriented applications such as the detection of biological and chemical materials, imaging through persons or container walls, and secure short-distance communication through the atmosphere. However, electronics-based radiation sources generally operate at frequencies below the THz regime, while photonic sources usually are efficient above - thus, the THz region is also referred to as "terahertz gap" between electronics and photonics. The ideal THz source is compact and inexpensive, operates at room temperature, and emits at least a few mW of coherent radiation. Quantum cascade lasers (QCLs) are based on artificial intersubband transitions which can be custom tailored for the specific application, and thus have an enormous potential as compact and efficient THz sources. For a more detailed overview about THz technology and quantum cascade lasers, see the Introduction and Sections 1 - 2 of the first interim report.