An electronic system. The electronic system includes a waveguide structure having a first waveguide-coupling point and a second waveguide-coupling point and an active electronic circuit having a first circuit-coupling point and a second circuit-coupling point. The second waveguide-coupling point is coupled to the first circuit-coupling point; the system is capable of receiving an input signal at the first waveguide-coupling point and transmitting an output signal at the second circuit-coupling point and/or receiving the input signal at the second circuit-coupling point and transmitting the output signal at the first waveguide-coupling point; the input signal and the output signal have frequencies in a terahertz frequency range; and the system is fabricated as a monolithic integrated structure having the waveguide structure fabricated by micromachining and the circuit fabricated monolithically.