Patent ID: 8693896

Claim:
A method for processing received electromagnetic radiation, the method comprising: 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; and filtering the received radiation with a filter that is tunable in the frequency range from 0.1 to 10 terahertz so as to obtain signal radiation carried by at least one carrier wave of the plurality of carrier waves, wherein the filtering comprises: generating a first wave with a first frequency and a second wave with a second frequency; frequency-mixing the first wave with the second wave so as to generate a reference wave corresponding to the at least one carrier wave carrying signal radiation; and frequency-mixing the reference wave with the at least one carrier wave carrying signal radiation so as to generate an output signal corresponding to the signal radiation carried by the at least one carrier wave; and providing the output signal to a detection circuit that is sensitive to at least one frequency corresponding to the output signal.