Secured spectral bands for wireless communication characterized under realistic conditions with a nonlinear optical receiver.

Terahertz radiation, which lies between the microwave and infrared regions of the electromagnetic spectrum, is being explored as a possible solution to meet the ever-growing demand for high data transfer rates. However, at these frequencies, strong absorption peaks due to water vapour in the air impose strict limitations on wireless communication. Here, we use a detector relying on a nonlinear optical upconversion technique to characterize spectral transmission of specific bands between 0.5 THz and 3 THz under normal atmospheric conditions. We classify these bands into two categories aiming at different applications: short-range secured communication and long-range high data transfer rates.