Bridging Optics and Electronics with Quantum Cascade Lasers, Antennas, and Circuits
Dept. of Physics, ΕΤn Zurich, 8083 Zurich, Switzerland
The terahertz frequency range, loosely defined as the range between 1–10 THz, has traditionally been lacking in convenient optical sources. Terahertz radiation has some important potential applications in imaging, chemical sensing and telecommunications.1,2 The long wavelength of the terahertz radiation enables a good penetration into heavily diffusing materials, such as foams or small-grained material. The vibrational modes of large organic and inorganic molecules are in the THz region, offering potential avenues for label-free sensing of DNA.3 The THz range has also some very interesting radio astronomy applications, as it contains, among other important spectral signatures, the brightest cooling lines of the dense interstellar medium ([CII] 158 μm, [ΟΙ] 63 and 145 μm) present in space. Because of the lack of transparency of the atmosphere in the THz region, such observation must be performed from airborne or spaceborne telescope such as SOPHIA, putting additional constrains on optical sources. For this reason, there is a strong interest in the development of terahertz sources that are tunable, portable and manufacturable in large quantities. Recently, much progress has been made in sources based on nonlinear generation from either ultrafast lasers or continuous ...