A method for processing received electromagnetic radiation includes receiving electromagnetic radiation having a plurality of carrier waves in the frequency range between 0.1 and 10 terahertz and having modulated onto the carrier waves information with a signal frequency of less than 50 GHz. The received radiation is filtered with a filter that is tunable in the frequency range from 0.1 to 10 terahertz so as to obtain at least one carrier wave as a terahertz signal. The terahertz signal is provided to a detection circuit that is sensitive to the terahertz signal frequency.