IEEE Spectrum: The SwissFEL laser team led by Christoph Hauri at the Paul Scherrer Institute near Zurich shows that one can use a commercial megapixel CCD to capture THz-band images. "It was previously known that low frequency radiation, when intense enough, could lead to dramatic changes in the semiconductor band structure. (For the intense light source they turned to a new and uniquely powerful source the SwissFEL team developed.) Long terahertz wavelengths force electrons to tunnel through the bandgap and the charge carriers start multiplying, leading to huge sensitivity."
The open access paper "High-performing nonlinear visualization of terahertz radiation on a silicon charge-coupled device" by Mostafa Shalaby, Carlo Vicario, and Christoph Hauri with the experimental results has been published in Nature Communications: