Design and simulations of a prototype nanocircuit to transmit microwave and terahertz harmonics generated with a mode-locked laser

Abstract

Earlier, we focused a mode-locked laser on the junction of a scanning tunneling microscope. This superimposed currents at the first 200 harmonics of the laser pulse-repetition frequency on the DC tunneling current. The power at each harmonic varied inversely as the square of its frequency because the spectrum analyzer and its cable formed a low-pass filter. However, analysis suggests that in the tunneling junction, the harmonics do not decay below 45 THz. We propose to make nanocircuits to mitigate the roll-off of the output power up to 45 THz. Each nanocircuit will have an optical antenna to receive the laser radiation, field emission diodes to generate the harmonics, and filters to select the harmonics transmitted by a second antenna. Harmonics that are transmitted in a bandwidth that is proportional to the center frequency for that band have an output power proportional to the square of the center frequency because of the fixed spacing of the adjacent harmonics. Thus, these nanocircuits may provide the greatest output power at frequencies approaching 45 THz. The harmonics may be modulated by the presence of specific chemicals or other local phenomena. Thus, scanning the laser over a group of nanocircuits could be used to measure these phenomena with unprecedented resolution.