Imaging with Undetected Photons in the Terahertz Frequency Range

Generation and Detection of terahertz radiation still remain a technological challenge, especially when compared to the visible or near infrared spectral range. For this reason, approaches are continuously pursued to transfer the terahertz radiation to other frequency ranges after interaction with the sample in order to utilize the advantages of the advanced detector technology. Novel quantum-optical concepts offer a further possibility to realize this transfer. This makes them an attractive alternative for the terahertz frequency range, as they only require cost-effective components such as visible continuous wave lasers and silicon-based detectors. We report on the first demonstration of imaging with undetected photons in the terahertz frequency range.