a heterodyne terahertz transceiver comprises a quantum cascade laser that is integrated on - chip with a schottky diode mixer . an antenna connected to the schottky diode receives a terahertz signal . the quantum cascade laser couples terahertz local oscillator power to the schottky diode to mix with the received terahertz signal to provide an intermediate frequency output signal . the fully integrated transceiver optimizes power efficiency , sensitivity , compactness , and reliability . the transceiver can be used in compact , fieldable systems covering a wide variety of deployable applications not possible with existing technology .