Scientists have developed a method to generate high-power signals at frequencies of 200 GHz and higher on an ordinary silicon chip, which could lead to microwave radiation being used as a nondestructive imaging technology to detect diseases, or for security purposes. The method, proposed by Ehsan Afshari, Cornell assistant professor of electrical and computer engineering, and Harish Bhat, assistant professor of mathematics at the University of California-Merced, relies on a phenomenon called nonlinear constructive interference, whereby signals are out of phase and their waveforms are distorted.
The researchers demonstrated this effect on a chip using a lattice comprising inductors and a grounding capacitor. When low-frequency, low-power signals are applied simultaneously to both the vertical and horizontal wires of the lattice, the waves they produce interfere as they meet across the lattice, combining many small waves into one large peak. It produces harmonic signals at multiples of the original frequency, and a high-power, high-frequency signal can be read out somewhere in the middle of the lattice.