A compact, continuous wave terahertz source for spectroscopy and imaging based on a quantum cascade laser

The Terahertz (THz) spectral range has a unique potential for many applications. One example is high-resolution spectroscopy of rotational transition in molecules which are relevant in atmospheric research or astronomy. Another example is imaging for security applications, biomedicine or non-destructive testing. For such applications radiation sources which are compact, easy-to-use and with low input power are required. THz quantum cascade lasers (QCLs) have the potential comply with these requirements [1-7]. However, until now, THz QCLs are operated either with liquid-helium cooling or with large cryo-coolers. While these cooling approaches might be acceptable for scientific experiments, they are unacceptable for most practical applications. We report on the development of a compact, easy-to-use THz source, which is based on a QCL operating at 3.1 THz and a compact, low-input-power Stirling cooler.